Warm Air Heating

(This is an element of ‘Heating‘)

The Saviour of The Company
(and quite possibly of the Gas Industry?)

The development of the Halcyon “Selective” Warm Air Heating System is a story of significance to both the Gas Industry as well as to William Sugg & Co and it does not start until after the second world war.

The Company had a busy time during the second world war in much the same manner as they had in WW1. More detail is in the History Section. As the production of armaments fell off and some huge orders for replacement street gas lighting damaged during the blitz were completed, my Father, Philip Crawford Sugg (PCS as he refers to himself in his piece, although most people knew him as Crawford), returned from the services to a situation which looked very unhealthy. He had held the post of Technical Director since before the war and of course the business had always been technically led with innovative products opening up markets. Fortunately, many years later, Crawford was asked to write an account of the inception and development of the warm air products and what better place to include parts of this than here. Before I do this, however, I must mention Crawford’s brother, Ray. Basil Raymond Sugg was the youngest of three brothers all of whom had a natural engineering talent and all went to the City & Guilds part of London University for their engineering degrees. The middle brother, Monty, died during the war and Ray was still too young to take part. However, he did join the Company in 1947 and played a major part in the development of his brother’s idea. When I approached Ray about his time at Sugg’s he said that he would like to write it himself and this is how his first hand account also appears. Sadly Ray was diagnosed with cancer during the time he was writing this account but he was determined to finish it and told me that it had been important to him and that he had enjoyed the task. Ray died in September 2005.


This description is typical of the care and thought that went into Sugg products and is really aimed at the technical (and Gas Industry) buff who would like to follow the thought process and development stages of a product which is to operate in an entirely new environment and indeed provided a huge step change in the demand for comfort in the home. Prior to this development very few houses were fitted with any ‘central’ heating and only large mansions might have a cast iron radiator system driven by a coal fired boiler in its own boiler house, stoked regularly by a member of staff! Just the number of years that went into this development seems extraordinary by today’s standard and it can be seen by the comments of ‘competitors’ producing quick copies – even down to painting them the same rather unlikely bright red colour – that other manufacturers were certainly not going to put in the same level of effort as described here. I make no excuses for including this account in full as it is an important illustration of ‘technical development’ of its time. Of course the question is, could any manufacturer actually justify a 10 year development period today? This is probably the last development of its type even compared to the low water content boiler which came later (see the section Low Water Content Boiler) which was probably more influential to the development of wet system boilers than any other single approach that is still in use today.


This document in hand written form was attached to a letter sent to ‘Ken’ by PCS dated 13th July 1976. (I believe that this is Ken Merefield who was a lifelong friend of PCS from the days at City & Guilds when they had gone out together to find their first job and Ken won at the toss of a coin because the interviewer could not separate them!) Ken had apparently asked for information on ‘early warm air gen’ and PCS replied that he could not answer this without ‘writing the bones of the story to clarify my memory’. He chose to write in the third person.

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Early warm air heaters 1946 to 1961

The interest of PCS in warm air heating was aroused by the loan from a neighbour to his wife of a portable Belling fanned electric heater to warm a nursery she was equipping in 1940. (This nursery was for their son CS!) This room was 19ft x 9ft in plan and 8ft. high. The very modest fan power resulted in a sensibly even distribution of heat throughout the room.

PCS was concerned that WS & Co of which he was technical director had been dependant largely on gas street lighting for over a century. The competitive position of gas for this purpose had become increasingly difficult since the development of the electrical discharge light sources. The sodium lamps produced a light at about 1/3 the cost of the gas source

His responsibility was to find new long term products for WS and Co. About 1,000 jobs and the family and other capital were at risk

On returning to Westminster after the war the first opportunity was taken to study the design of a gas fired domestic air heater whilst the development of two further gas street lamps was completed and the accumulation of lighting work arising from the war kept the factory busy.

BR Sugg (PCS’s younger brother) joined the small laboratory staff. The first design study envisaged water to air heat exchange with an output of about 50,000 BTU/h suitable for district test in PCS’s house in Purley. The design was not implemented being considered too costly and difficult to control and unsuitable to the available plant. PCS. then decided to make for test a quarter size model say 11 – 12,000 BTU/h on the direct gas – air heat exchange principle and to study the problems of material selection and thermal stress inherent in this. WS & Co had no large presses to make the American style clamshells so a multi tubular configuration with narrow tubes closely spaced, 2 pass air circulation and forced product circulation was designed and built. This unit is illustrated in fig 4 of I.G.E communication 796, 1969.X CHECK

One motor drove both air product fans and the motor was DC so that it’s speed could be varied over a wide range. Although much advice had been taken on heat transfer coefficients, the products were emitted as a jet of steam. New centrifugal air circulation fans were made (they could not then be bought) and one or two simpler downflow models were made. From there it was decided that a single pass of air through twelve mild steel tubes about 2.1/2 inches x 3/8 inch x 6in. long would meet the desired duty. To stop these collapsing inwards at the bottom they were widened to half an inch and pushed on to spigots on a grey iron casting above the burner and one Bray jet was arranged under each tube. The flue fan was omitted for simplicity.

The noise level of the “home made” circulating fans on models 2 and 3 mounted directly on four pole motors, was unacceptably high. A 2-bladed axial impeller, carved initially from balsa wood, and later made as an aluminium casting, hand finished 7in. in diameter and working in a converging shroud was therefore made. To overcome problems of motor temperature rise from stored heat when the unit was stopped, the fan was fitted below the heat exchanger, hung on three rubber mountings by bolts and keyhole slots so that it could be readily detached by lifting and turning.

This assembly operated quietly and gave adequate circulating airflow, assisted by natural convection as to about 1/3, with 2/3 provided by a fan and motor of 7-9 watts output, 4 pole (hence the term ‘fan assisted’ still incorrectly used for other heaters.)

A draught diverter for back flue outlet was evolved with considerable difficulty and combined bi-metal flame failure and fan failure valve designed and made. The latter duty was effected by continuously heating one end of a copper strip by radiant heat from the bottom header casting. This heat was conducted to a bi-metal shaped hook kept cool in normal operation by a small jet of air from the fan. If the fan stopped, the bimetal hook, still heated, moved and released a spring loaded plunger to pull the ball shaped gas valve onto a seating below it to cut off the main burner. Manual resetting was necessary.

An automatic fan control was then evolved, with a stainless steel probe above the end burner flame, a heavy copper rod forming a ‘heat sink’, bimetal strip and micro switch. This was assembled in a steel channel with pilot light at top, socket for fan motor and mains terminal block at the bottom to form a complete wiring unit and fitted on the side of the heat exchanger.

These controls which later seemed unorthodox became very reliable with minor production changes. No alternatives were known in the UK for some years.

A decision was taken to defer the forced flue feature and the complete assembly was fitted in a folded sheet aluminium painted casing with a louvered front warm air outlet and wire mesh side inlets. Tests of heating effect and noise level were made at Purley and thought satisfactory. The noise level was studied by waiting for a calm night in the early hours.

A first batch of some twenty such units was made christened “Halcyon Type H” and arrangements made for a test on the district. The name Halcyon was conceived by Mrs BR Sugg (Ray Sugg’s wife, Betty) following a competition for a small prize. The heat output was 12000 BTU/h, circulating volume 112 cfm.

To increase the flexibility of application, an alternative top flue gas header box with a ‘spout’ projecting between the two upper front louvres was evolved so that the unit could be used fluelessly if desired with much dilution of the flue gases. Such units were called “Halcyon Type HX”; heat output 16000 BTU/h.

It was now late 1947. (BR Sugg thought this should be 1948 as they used an alpha method of designating the Halcyons’ and H would be the 8 of 1948.)

District Tests Models H and HX
These tests were made in widely varying conditions with a view to determining among other factors:
User reaction to a free standing warm air heater, flued and flueless.
Life of the mild steel heat exchanger tubes, regarded as consumable.
Interval for normal maintenance.
Liability to dust accumulation in any part
Reaction of Gas Companies to an appliance having an electricity supply.
Reliability of controls
Possibilities of concealed mounting.
Type H was fitted in the houses of PCS & BRS for personal observation. These had clock control.
Type HX was fitted in the hall of AG Higgins house at Beckenham.

By arrangement with the Croydon Gas Company, who donated the installation, several units, including one ‘double version’ with two heat exchangers in one casing, were fitted by RE Johnstone (Industrial Engineer) in the Church Hall of West Croydon Congregational Church. This was riddled with dry rot and its regular use by Boy Scouts for football ensured an ample supply of dust. Horizontal and vertical temperature gradients were measured and were satisfactory despite broken window panes. The heaters did not block with dust.

Test heaters were fitted in large waiting rooms and in shops and offices and furniture showrooms.

It was found that the performance of these small free standing air heaters, the flued version of which had an efficiency of 75% even when turned down to 1/3 output, compared very favourably with then existing domestic heating appliances. Gas fires were of the radiant type, about 40-45% efficient and the rapidity with which warm air carrying 12000 BTU/h heated evenly and economically a typical room opened up a new concept in space heating by gas in the United Kingdom.

Vertical temperature gradients of 7 degrees F and horizontal differences of ½ degree were recorded.

Annual removal of slabs of rust which formed inside the consumable heat exchanger tubes during the summer proved necessary, everything else seemed satisfactory.

Noise level, a major concern of PCS & BRS, had proved acceptable with 9w of fan power without deliberate attenuation. It was known that American warm air systems were tolerated as to noise in their country of origin but were unlikely to be acceptable in the United Kingdom dwellings by occupants with no previous experience of fanned gas appliances.

The Gas Companies showed no resistance to the inclusion of an electricity supply, equivalent to about 1 unit / day for Halcyon Type H.

The advantages of the air circulation engendered by this kind of appliance were quantified by recording temperature gradients using a flueless heater with and without the fan working. It was found that the more even distribution of heat resulting from the circulation reduced the heat loss through the ceiling and upper walls of a structure for given ‘breathing zone’ temperatures to provide a saving of 10% on input.

Despite emphasis on the consumable design of the heat exchanger eventual replacement of which would cost £2, a steady demand built up for the models H & HX. BRS designed a moulded Bakelite fan impeller to replace the hand finished cast aluminium fan.

Later a model J53 with improved appearance & louvres but unchanged internal construction was put into production. Both units were assembled in the small ‘stove shop’ by craftsmen.

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First use of ducts with Halcyon “Selective” Heating.

Meanwhile PCS decided to heat his lounge as well as his hall. The uncased unit was fitted with a 10”x 10” duct adaptor in place of the front louvre and mounted on a box base inside which hung the axial fan. (See basic heater drg No. H1679).

This was mounted in a cupboard built under the stairs, flued rather poorly and fitted with a duct tee-piece with a diverter so that the output of warm air could be directed into either space by moving a lever; air intake was from the hall. A magnetic valve and Satchwell P room thermostat were added. Grilles were of very low resistance.

So effective was this in providing ‘quick comfort’ that a similar installation was requested by the neighbours from whom the old Belling electric heater had been originally obtained. This also was under the stairs.


The lounges were in each case about 20’ x 12’ and were heated to 65 degrees; good background heating of hall and landing with some heat to open bedrooms was provided by diverting the output to the hall.

This was the genesis of “preferential heating”, later re-christened by D.R.Wills “Selective Heating”. The output of the unit was linked, with some margin, to that required to rapidly warm the room in which the occupants of the dwelling relaxed and not to the heat requirement of the whole house.

Gas was regarded by the public as a very expensive fuel in the 50’s and early 60’s, to the point where estates were built without any gas mains and the continuance of the industry was in doubt in many minds.

The Selective heating system linked an appliance with nearly twice the efficiency of a gas fire and of low thermal capacity closely to the general living pattern of the users. The existing whole house wet central heating systems of the time were so slow in reacting to the needs of the occupants that they were necessarily operated continuously during the day. They consumed much more gas or required frequent stoking; room thermostats were virtually unknown in houses.

Except in the severest weather (the Purley houses were at an elevation of 400’ and 420’ respectively) the central heating radiators were no longer used as the acceptability and economy of the very simple air heating systems became apparent.

Further box base axial fan selective installations were made in PH Sugg’s house at Norbury and BR Sugg’s house at East Horsley, the latter with a vertical duct to an upper floor.

The opinion was formed that the capital and operating costs might each be about 1/3 of the then existing gas heating systems.

There was, however, very little demand for heating equipment fired by gas and no attempt was made to sell except for a few special requests.

The heat exchanger had been in use for 5 years unchanged; the aim was 10 years, a yearly cleaning was still necessary to remove rust.

Mr S.G.Aberdein, then commercial manager of NTGB, asked Mr AW Self of the Headquarters Section working under Mr JA Buckley, District Manager of the Wansted & Woodford area, to investigate warm air heating.

Three of the box base axial fan units were fitted in a large fireplace in Wansted Golf Club and concealed with a wrought iron grille. Several similar units, some with 100% fresh air intake, were installed in a large public house in the same area, with control switches under the edge of the bar counter. Both these installations proved successful, the latter particularly so in dispersing tobacco smoke from a very large public bar.

The whole philosophy of the development work to date, based on low level, low velocity discharge of warm air was shattered by the imposition of 100% purchase tax on all domestic appliances connected to the mains electricity supply. This was due to an acute shortage of generating capacity over the whole country.

After long negotiations with Customs & Excise, in which the GEC wall mounted fan heater was cited as free of tax, PCS was able to agree a formula for the use of the Halcyon mounted 6’ high, limited to commercial & industrial premises only, free of purchase tax.

The heat exchanger was “stretched” to 17,000 BTU/h output without any alteration of design – the axial fan was increased in diameter and produced with four blades, requiring a new Bakelite moulding and 20 W output motor. At the request of Customs, the air intake was made in the bottom only of the casing and this was sloped to “prevent” floor mounting.

This unit became model W and in single and multiple form proved acceptable to commercial and industrial clients.

The earlier tests of this type were again made in Wansted & Woodford, notably in a wallpaper warehouse, where stock damage was prevented and in a multiple store block (in considerable number) in Romford. A long narrow drapers shop was fitted with 3 Type W units mounted on the back wall through which they were flued, and 10” x 10” ducts about 10’ long discharged the warm air over the top of the cash desk at the rear.

A diagrammatic leaflet was issued in 1955 which included a few simple duct components and examples of their use and the wall mounted heater was adopted for a variety of commercial premises, hutted LCC schools and small workshops and offices. The fan power was just sufficient in conjunction with an efficient curved blade front louvre to direct the warm air to within about a foot of the floor. The noise level would have been unacceptable for domestic heating, the fan being 9.1/2” diameter and rotating at 1440 RPM. The wall types were also made available in double and treble form and gave general satisfaction. Increasing use was made of duct parts and fresh air ventilating facilities (Type 32V etc)

Duct parts and the very low resistance outlet grilles (necessitated by the characteristics of the axial fans were made by WS & Co, their being no other supply. “Weep line” thermostatic control was made available as an option.

This drastic change in application kept the “Halcyon” ‘alive’ during the period of high purchase tax with an annual output of perhaps 800 units. Much experience in dealing with heating problems was acquired by staff trained mainly in gas lighting matters, enthusiasm was generated by the appearance of a new outlet for their considerable energies.

Confidence in the durability of the heat exchanger tubes, still described as ‘consumable’, increased. With the adoption of the chrome diffusion process for these parts, PCS felt that the heat exchanger problem was probably solved and development towards wide scale use could safely be initiated. While “living” on its commercial version the original domestic use was therefore pursued.

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In 1952 D.R.Wills , then concerned with approval tests at Watson House had suggested that a centrifugal fan, as originally envisaged, should be used as having a more suitable characteristic where warm air ducts were to be used. Several units were adapted , the fan rotors being made by rolling and welding the pressed louvre strip into a cylinder and mounting this on cast aluminium end wheels. This rotor rotated on sealed ball bearings, prefabricated, with forward curved blades at about 400 rpm. Drive was by rubber belt from the 9W BTH 1304 motor, set into the casing side in the cool air stream. A volute was formed between the side sheets of the heater casing, discharging upwards into the existing and by now well proved heat exchanger. The casing was altered to floor standing .

Again fiscal matters intruded and the motor and governor and magnetic valve were detached and supplied separately to avoid Purchase Tax on the parts (?60%). The motor thus had to be fixed to the floor in one of two positions to suit the drive belt: tension adjustment was provided, holes ready drilled asbestolux baseboards were supplied to simplify installation.

The following 7 pictures were sent to me by Paul Ewing following contact through this website in january 2015. It seems this unit was discovered in the state you see here complete with ducting with controls for distributing the warm air and even the asbestolux baseboard mentioned in the paragraph above.  You can also see the magnetic gas valve with its separate 3-pin 2 amp plug and socket to avoid purchase tax. The second small 3-pin socket supplied the fan motor which is missing from the mounting bracket to the left where it was fitted to drive the centrifugal rotor via a circular section rubber drive belt. This is the only Halcyon model that was painted bright red but as you can see was always intended to be housed away from view having no fancy ‘casing’.

_Front-high-left-P1080164[7] Top-RHS-P1080165[7] Front-horiz-P1080160[14] Front-higher-P1080161[16] Front-half-rt-P1080163[8] Controls-vert-down-P1080162[4] Controls-angled-P1080166[13]

The fan control was omitted completely because no means of service existed for electrical components on gas appliances in domestic use. The leads of the fan motor and magnetic valve were fitted with plugs and sockets for the same reason so that they could if necessary be replaced by a gas fitter.

This was the genesis of the F45 Halcyon Heater. Fixed under the stairs in PCS’s house at the new rating of 17,000 BTU/h output the new centrifugal fan proved acceptably quiet and the additional output improved the selective heating, particularly in the hall and landing and bedrooms with open doors were always “comfortable” as then judged.

This unit was operated continuously, burner off in the summer, for duration test of the fan bearings and drive and rubber mountings. After 300m fan revolutions it was dismantled and the bearings and seals returned to SKF for examination; this confirmed the aim that their working life would be indefinitely long in the conditions of use.

Two further F45 type units were installed in a large new bungalow at Virginia Water. (It is notable that these were converted to natural gas about twenty years later). This bungalow was ‘L’ shaped in plan and the use of two separate heaters and duct sets, both of which could heat the large lounge, avoided the use of long ducts and set a pattern much used in later years and which still retains many advantages for the user. No ducts at all were used in this bungalow; the heater discharged between two airtight ‘asbestolux’ shelves sealed across the small heater compartment. Special register units set in the walls of this controlled both the warm flow and return from the main rooms simultaneously by movement of a knob. This was called “push-pull” heating and proved very effective in reducing loss of air up chimneys etc by maintaining neutral room pressure.

No other examples of this practice were used; the special registers were too costly.

Another new test house for selective heating was built at Wimbledon for Mr Tony Bishop, director of an SBGI firm. This also had two “F45 type” units with stub ducts on the ground floor , but vertical ducts were extended to the first floor rooms. Each heater was controlled by two room thermostats connected electrically in series, one upstairs and one downstairs. Both heaters could heat the large open plan lounge and one heater could ventilate it in summer.

These heaters and a water circulator were initially flued into an attic ventilated by large louvres in each gable. Condensation occurred on the water tank etc. The three flues were then extended and fitted with fan shaped sheet aluminium “fish tails” which passed alongside the ridge board of the roof. The ridge tiles were lifted about 2” and wire mesh fitted to exclude birds.

This arrangement worked well and was the forerunner of the ridge flue terminal now so widely used.

Mr A.L. Gray, an architect and PCS’s brother-in-law, having experience of selective heating in the latter’s house, decided to incorporate it in a luxury house he was designing for himself. This house was split level and the heater was sited in a box-like telephone fitment in the hall adjacent to the change of level and about 3’ high. A vertical duct built integral in a “thermalite” dividing wall at the side of the heater enclosure conveyed warm air to the main bedrooms and landing; selective outlets lead to the lounge, kitchen and hall.

Again this proved highly successful and noise levels fully acceptable.

The outcome of the experience gained in this extremely slow process of consulting with the architect and then waiting for the house to be designed and built and occupied for at least one heating season was that PCS was able to claim for the Halcyon selective system that the capital and operating costs were about half those of then existing gas central systems and that user satisfaction was excellent.

It was with some confidence therefore that an F45 unit was fitted in Mr Neil Wates first house in Chester Row, London in 1955 at the suggestion of E.H.Harris of NTGB HQ Division. The whole installation, including test meters, was planned and commissioned inside three days, the heater being fitted in a basement of the 150 year old house. Mr Wates installed a thermograph in the hall, which showed virtually a constant temperature throughout the following winter.

SE Central Laboratories at Old Kent Road had been kept in touch with all the domestic test work and the Board had used many of the wall mounted models in commercial premises. Mr Fuidge, then manager of the laboratories, introduced PCS to Mr J.R.Blackwell the Special Services representative in whose area Wates, Norbury headquarters was situated and Mr Blackwell was made familiar with the latest developments of the Halcyon.

In August 1956 PCS received a ‘phone call from Norman Wates (Chairman) asking to see an installation the same day.

PCS found himself leading a convoy including many of the principle officers of Wates from Norbury to Purley and later to the test house at Chipstead.

The prototype Wates “Dormy House”, a large open plan bungalow owing lineage to Wates operations in the United States was then erected in a few weeks at Sutton and fitted by PCS with an “F45 type” heater and selective duct set, all located in the lower part of a large airing cupboard and clock and thermostat controlled. South Eastern laboratories finished and instrumented the dwelling and with difficulty, because it was the time of Suez and petrol was rationed, simulated living conditions in it for most of the winter 56/57 & distributed their test report nationally to the gas Boards.

PCS, armed with a pass key and the freedom of the test “Dormy” house “sold” the system to his own management mostly on the score of the rapidity of heating after deliberately leaving the unit off and subsequently to builders and authorities from all over the country who visited the house.

Before the Dormy House tests were started Wates altered their standard maisonette and flat 3-storey block to take selective heating. These dwellings, erected first in 1957 at Ardmay Gardens, Surbiton and for many years subsequently throughout London, were complete when one purchaser asked for clock control. This feature was added to all the dwellings and thereafter its use became almost universal, despite the extra cost.

It is notable that the Surbiton dwellings were also fitted with incinerators and drying cupboards heated by the Halcyon because there were no fireplaces and limited garden space. Use was made of a 6-way “True flue” to discharge all products, smoke and damp air. This practice had to be discontinued because fly ash entered the other flues, packed too closely together.

Wates were given six months start with the Halcyon, during which they gave it and the Dormy House much publicity, including a full page of the Evening News (“the scarlet boiler”) and the delivery by Mr Neil Wates of lectures in various parts of the country

Mr J.R.Blackwell then introduced PCS to New Ideal Homes at Epsom. After demonstrations this company changed all its house designs to incorporate selective heating by Halcyon: Many others followed, all in the private sector.

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This initial period of rapid growth of interest in selective air heating was notable for several factors which influenced subsequent development of the market. These include –

  1. PCS, ignorant of the merchant trade, dealt direct with the Gas Boards who handled the business for, say, 10% and often carried out the installation very cheaply. This was because each Halcyon represented several times their average domestic annual load.
  2. PCS accepted that there was then virtually no available capacity for designing warm air duct systems. The Halcyon literature therefore specified one size only of duct (later 12” x 6” was added), with stringent length limits on ducts for heating principle rooms and a greater length for ancillary rooms; vertical ducts were not counted in these limits. Any architect or builder, without previous experience of warm air heating, could envisage a practicable system from these and other instructions on the Data Sheet. By submitting his small scale plans to WS & Co he could have working drawings and bill of quantities free of charge. These drawings could be prepared without calculations, providing the dwelling was within the prescribed limits of size.
  3. Mr V. Stanton, then Commercial Manager of South Eastern Gas Board introduced special two-part tariffs for the heater. He also successfully negotiated with Customs & Excise the complete removal of purchase tax from the selective heating equipment on the grounds that it was a “central system”. This was done between midnight, when PCS was asked by Mr Wulstan Atkins for a complete illustrated history of the Halcyon to date for delivery to Mr Stanton by 9 a.m. the following day.
  4. Competitive gas warm air heating systems at the time included the elaborate whole house chimney furnace system developed by Dr Davison of Radiation which was relatively complex and expensive and required careful design techniques. There was also an adaptation by Coy of Derby (later Heatinaire) of an oil fired air heater which made a great deal of noise. It was noticed that after some comparative tests against the Halcyon, in an adjacent house of this latter unit it changed in six weeks to a virtual copy of the F45 Halcyon, painted the same colour but without the long life already built into the Halcyon by the 10 years experience of its heat exchanger.
  5. These comparative tests again carried out by SEGB Central Laboratories led to the first bulk order from Wates.
  6. The demand for the “Dormy House” became such that Wates licensed other builders, “spreading” the Halcyon, which was in the bill of quantities, to other Board areas.
  7. WS & Co took “one night stands” in many major cities with demonstration models of heater compartments. The audience was invited in collaboration with the Gas Boards. At one such meeting in Edinburgh the City Engineer proposed the incorporation of a water heater.
  8. SEGB, as a result of the efforts of their Special Services Section and Mr Blackwell’s detailed knowledge of the new housing market, both private and public, staged a demonstration at the Savoy Hotel with the Sugg models. A prominent sign showing the number sold was continuously up-dated during the function, well attended by invited architects and builders. This was repeated a year or so later with SEGB & NTGB as joint hosts.

In the meantime Mr Fuidge and his colleagues Mr Carne and Mr White had evolved the “Seduct” common flue system for high buildings, then popular, mainly in the public sector to help gas compete with the widely used electric underfloor heating. Mr Fuidge asked PCS for a room sealed air heater for this form of flue, already in use with Ascot water heaters in a block of flats in the North East.

Two header castings from the F45 heater were bolted together with the tubes between and sheet metal manifolds fitted to the headers, respectively to enclose the burner and form a flue manifold. This assembly was mounted diagonally across a vertical casing with lift off downflow fan unit on top; in flats low level duct would be used. Spigots to connect to the Seduct were fitted outside the casing to the manifolds of the heat exchanger. The fan unit employed a 9 W motor and belt drive to an F45 fan rotor.

This was sent to the Old Kent Road where it was tested extensively on the original sheet iron Seduct. It reappeared at Westminster finished in a totally different colour, but was judged workable.

From this evolved the Halcyon F/SD Selective Heater. Because of the increased exposure of the upper part of the building the output was increased to 22,000 BTU/h, with larger section heat exchanger tubes and 6” diameter drums for the burner and flue manifold on to which saddle shaped iron header castings were bolted with an asbestos rope grommet.

To obtain a seal at the ends of the heat exchanger tubes the ends of these were linished and the length kept within close limits. This heater employed chrome diffused tubes from the start. The saddle castings were machined on the flat surfaces and a separate stainless steel plate with pressed spigots to enter the tubes was fixed to each machined surface, with a thin asbestos gasket on the top only. The long rods clamping the castings together were fitted with heavy spring washers to permit some differential expansion.

This F/SD heat exchanger, with minor modifications mainly to strengthen and improve the location of the spigot plates on the saddle castings, was designed to be adaptable to all forms of flue and water heater and over a period was used in this way with great advantage.

The detail design of the Heater, with its belt driven fan and 9 W motor was the work of Mr Eric Petty of Suggs’ drawing office.

Approval testing was carried out at Old Kent Road on a ‘Seduct rig’ and some improvements made there to the pilot and thermo electric flame safety arrangement. The FSD Halcyon was ready for use in 1958.

Wates used many of these Seducts in their tall blocks at Dulwich closely followed by their adoption by the Harlow Development Corporation in the same year.

Because it was necessary at that time to manufacture in batches and few Gas Boards knew what type of flue would be used, this heater, while designed for the Seduct, could be fitted to conventional flue by the addition of an elbow and draught diverter or clamped to a balanced flue assembly. It was therefore of universal application and was accordingly renamed F60.

It was eventually used everywhere in the UK.

It is perhaps notable that when, many years later the Canadian style duration test was introduced for approval because of stress cracking of clamshell heaters, the F60 multi tubular design survived the test twice in succession without any damage – it was to an extent flexible, relieving thermal stresses as they occurred.

For some time the combination of the FSD heater and Ascot instantaneous water heater, both mounted in the same cupboard backing on to the Seduct, was widely used, sometimes with a special Clifford drying cupboard heated by warm air and ‘flued’ into the Seduct through a Sugg solenoid controlled flap valve fed through a door switch from the heater.

Ascot produced a glossy catalogue illustrating these arrangements which set a new standard in Industry Publicity material.

The next development of the F45 selective heater was the incorporation of the Maxol WAS30 water circulator in the back of the enlarged heater casing. With purchase tax removed from the air heater it was logical to remount the motor, governor and magnetic valve on the heater and to enclose these parts inside a hinged cover. The circulator however carried purchase tax at a high rate (possibly 60%.) Separate ordering of the circulator and “on site” fixing in the air heater was the only alternative to attracting purchase tax on the whole, including the air heater, which PCS could negotiate at the time.

When submitted for test to Watson House, Mr Leslie Andrew interceded between Radiation and PCS for the use of a special model of the well known “Circulyn” water heater in the F45WH. This necessitated a further enlargement of the air heater casing; nevertheless the air heater was available in June 1960 and would accept either Maxol or Circulyn water heater kits, with flow and return water pipes to either hand as required.

The F45WH, being for conventional flue only, was easily fitted with a water heater once space was made available and the problem of “marrying” the air heater and water heater flues was solved.

The FS/D or F60, room sealed for Seduct and Balanced flue and used open for conventional flue proved much more difficult. The circulator was enclosed in a sealed compartment at the front of the air heater, with window for observation of the flames of both appliances.

The flue of the water heater passed horizontally through the upper drum of the air heater heat exchanger, which had been originally made large enough to permit this. The spigots for Seduct and Balanced flue terminal were enlarged, as was the balance flue assembly. Much difficulty was experienced with the “plumbing” of the burners and pilots and magnetic valve and the numerous cocks.

This one unit required nine separate approval tests to cover all its combinations of use and application.

However by April 1960 the F60WH heater became available. PCS felt he had departed from his aim of achieving simplicity at all costs.

It is perhaps notable that the incorporation of the Circulyn in the Halcyon lead to the largest single demand for the former, sales of the Halcyon Kit outstripping the original application as an independent water circulator.

It is not intended here to deal with other Halcyon Heaters of greater power intended for whole house heating with orthodox duct equipment. These included F120/WH (45000 BTU/h), which was developed by PCS with a larger multi tubular heat exchanger of similar general design to that of the F60 heater and was completed in 1961. The type 35 (35000 BTU/h) and succeeding versions of the 60 were developed with much better facilities including Seduct Test Rig, Duration test room and Test gas supplies in a much enlarged laboratory under the manager ship of Mr GT Blench.

In Retrospect: (Don’t forget this was written in 1976.)

The majority of the F45 and F60 type heaters, now converted, are still in use. Because they are ‘built in’, arrangements have been made by Thorn Heating Ltd, who purchased W.Sugg & Co Ltd in 1969, to rebuild these heaters as new or their heat exchangers if desired as and when required and to provide a ‘float’ of heaters to facilitate such operations for the foreseeable future.

That a working life of 20 years had been achieved confirms the choice of materials and suitability of the original designs, the main feature of which was evidently the ‘freedom’ it permitted for differential expansion of the heat exchanger components.

Sugg built over 1/3 million selective warm air systems and in the middle sixties was equipping 20% of all new domestic construction in the UK. Almost without exception these satisfied their users comfort and pockets.

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Notes from Chris Sugg, son of Philip Crawford Sugg (PCS).
I well remember the test work carried out on various Halcyons’ at our house in Purley and how my girlfriend, Sally – later to become my wife, complained about the heat in the house. She reminded me that as a child her bedroom had a gas fire which her father used to light for her in the morning whilst ‘Jack Frost’ was on the inside of the windows!
Two extended flue tests failed to impress. The first was a conventional flue which ran the full width of the garage and collected a huge amount of green crystals. The second was a trial forced flue which ran out along the floor from the heater cupboard in a piece of 2 or 3 inch Kopex flexible pipe and through the wall into the open entrance porch area. We were awoken by frantic knocking on the door by the early postman who was convinced that we had a fire, as on a cold morning the flue products produced a fine plume of condensation which he took to be smoke.
The first floor-standing cased version of the F45 which was trialed in the hall in Purley went on to provide temporary heating in the first two houses that Sally and I bought by simply placing it in a fireplace and plugging it into the gas poker point. In both cases the houses were eventually fitted with warm air systems – the first a 22TN and the second an Ideal Home Exhibition white painted Type 35. Both the latter and the early F45 were presented to the Science Museum as important stages in the development of warm air heating – and the survival of the Gas industry.
Later when I joined the William Sugg company as a production engineer I was responsible for producing an assembly “flowline” method of production to increase the rate of manufacture. At that time we achieved 1000 units per week.

The Halcyon proved to be exceptionally durable. In 2012 I spoke to a specialist heating engineer who had serviced and replaced many Halcyons that had been operating for upwards of 50 years! As he said wouldn’t it have been a fabulous sales gimmick to promise a 50 year life! C.S.

Halcyon Model 22WH fitted with Ascot Water Heater.

 22WH 3 260 22WH 1 260
22WH 4 260 22WH 6 260
Design Manual 260 Design Manual Flue terminals 260
Design Manual Typical bal flue installation 260 Design Manual UR duct installation 260 Design Sheet 1 550

The Halcyon Range Advertisement




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(A portion of the following essay, in three parts, relating to the description of the two factories, has now (2011) been moved to the ‘history’ section to provide a snapshot of the poor state of the business immediately after the war.CS)

As mentioned at the beginning of this ‘warm air heating’ section, Ray (Basil Raymond) Sugg, who was the youngest brother of Crawford (Philip Crawford) Sugg, joined the Company after the war in 1947. He was to help his brother with the development of new products essential to the survival of the Company which could no longer rely on its past products and was in a pretty moribund state as is indicated in his description of the factories at this immediately post war date which you will find in the ‘History’ section.

From BRS – Basil Raymond Sugg – written in 2005 just prior to his death.

Crawford had been at Sugg’s for about 18 months before I arrived and had been formulating his plan for new products to replace the street lighting business. This had been killed by the development of high efficiency electric lamps, and by the withdrawal by the newly formed Gas Boards of the favourable tariffs which many gas companies had offered for street lighting. His decision to concentrate on small to medium heating units, and on warm air in particular, had already been made (see I.G.E 1083 page 33). During my first few weeks we took a number of decisions which dictated design for almost ten years:-

  1. Multi tube heat exchange
  2. Rectangular tubes used with aerated flat flame Bray jet
  3. Air inlet vertical, outlet horizontal
  4. All electrical equipment to be serviced by exchange without special tool.

Len and Bill set about preparing the lower floor with gas points, benches and test gear. To start with, we had an overhead belt drive to a brass finisher’s lathe and elderly drill, but these were replaced fairly soon by a 5 inch motorised lathe and precision motorised drill, plus a fly press. I installed drawing equipment and started a combination of design and test work.

The most important factors to establish were the relationship between burner position, air flow and exchanger temperature and we made a lot of use of temperature sensitive paint to find hot spots, followed by thermocouples. Bill must have made dozens of the latter.

As we approached a working design, it became necessary to find out what could be made in Vincent Works and I think it is important to describe this scene as it was then, as so many changes followed later. This was probably its lowest ebb.

The description is now in the ‘History‘ section.

Harry Burns acted as my mentor, showing me the way to use the systems and there was great enthusiasm at floor level for the possibility of new products. (It is only fair to add that enthusiasm was totally lacking at Tommy Mattock level). Before the end of 1947 we had in hand:

Patterns for the combustion chamber top (iron castings had to be made outside.
Patterns for the two-bladed fan, with aluminium castings made in house
Patterns for the flame failure device body, with gunmetal castings made in house
Sets of sheet metal parts for the heat exchanger body and the casings, plus a number of small tools for this work
Tools for forming and welding the heat exchanger tubes
Spinnings for the fan housing and nose fairing.

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BRS history 2 – 1948-1951

The process of design, sample, test and modify if necessary on the Halcyon heater was the chief work during 1948 –1949, but there were gaps when other jobs could be fitted in. I cannot be sure of the chronology, but some are worth recording.

The winters at this period were unusually cold in London. The system of coal gas distribution involved a primary system at fairly high pressure, feeding district governors which reduced the pressure to the consumer. In the South East Gas Board area these district governors were housed in roadside kiosks, very like those used by BT today, and in cold weather, there were difficulties with poor governor performance due to stiffening of the leather diaphragms. This was being dealt with by putting oil heaters in the kiosks, but unfortunately one sprung a gas leak and literally blew its top, causing great concern to a population which had only just started to forget bombs!!.

Crawford was approached and suggested a balanced flue gas heater, which we then set about designing. The final version looked like a gas fired trombone, consisting of two 2 foot lengths of 1” copper tube, joined at the bottom by an H shaped casting which contained a Bray pilot jet and a little lighting window. The top ends of the tubes were fitted with double elbows so that they could pass through the wall of the kiosk into a balanced flue terminal, which was loosely based on the top of an 8000 lamp. These units proved successful in winds and snow and in the region of 100 were made. The only problem which occurred occasionally was that if the flame became unstable due to excess pressure, the tubes started to resonate with a loud note about upper A!!

A second project which originated from SEGB was the supply of cooker thermostats. The Board had decided to make their own cookers because they could not meet the demand from normal suppliers. All parts were in hand but Radiation could not (would not?) supply oven thermostats. We agreed to help and I designed a thermostat very similar to Radiation’s but sufficiently different not to infringe their rights. This was accepted after trials and I believe that about 100,000 were produced during the next few years.

The third gap filler project was the Stokes heater. (Richard?) Stokes was an engineer in the Eastbourne/Hastings area of SEGB faced with the problem of trying to heat dance halls and similar facilities which the resorts were trying to start up after the war. He had done a great deal of design work on his idea of a combined light and heat unit, including the external shape designed to spread reasonably uniform heat over the floor when mounted at about 10 feet high and 12 feet apart. We adopted all his work which proved to be correct, but getting to the finished job was difficult. We had the heat source, the gas control system and the glass ware.

The heat radiation outer spinning was bigger in diameter and depth than anything our spinning shop had tackled in steel. Three huge formers were needed to reach the final shape and a more powerful hydraulic spinning tool had to be obtained. It took several months until a finished spinning was available and in the meantime Len and I had been busy making moulds, pouring fire resistant cement in them and drying and firing trial bricks. (I knew where to get the cement from my wartime experience on naval boilers at Samuel Whites in Cowes and we cooked up an old Sugg domestic oven to about 350 C to dry them out).

Towards the end of 1948 we had a couple of complete prototypes hanging in the laboratory and they performed excellently. You have to remember that combustion products testing involved the use of the Haldane type of apparatus and took some time – how much time modern analysis apparatus would have saved.

We thought we were OK to proceed but after a few weeks tiny flakes of hot glass started to drop off as the vitreous enamel failed to withstand the temperature. We were stuck for several months until news of a new product “Stoneclad” from a firm in the Potteries reached us. This was claimed to be the use of a slurry consisting of all the constituents of a natural rock except iron, which combined with the iron spinning when fired . It worked well and looked attractive, a nice shade of light grey. I think it was probably spring 1949 before we could let an impatient Mr Stokes have units for district trials, which were successful and orders began to come in.

I planned and supervised two installations, one in the Garrison Church of Albany Barracks, just off Regents Park, using eight units and another in the very different environment of the Art Wallpaper warehouse in Romford, using 12 units. Both were well liked by the customers. This was a time of acute energy shortage and a number of Councillors objected to having lights on in Public Halls during daytime. We produced another version with a Bray ring burner and a metal spinning in place of the glass and I guess sales over a period were about 50/50.

Back to the chief project, by the end of 1948 we had built and tested several Model H units in their utility casing and one Model J with smart rounded corners. The only unsolved problem was corrosion in the heat exchanger tubes. This took the form of a thin film of black iron oxide, probably with some iron sulphide, and did not interfere with the passage of gases while it was attached to the tube wall. Unfortunately when the heater was not in use and became damp, it cracked off and could fall across the tube causing major blockage. We decided that an annual service was probably adequate and that domestic trials could start, but it was several years before the problem was solved by chromium diffusion treatment. I am not sure how we learnt about this, either from Mr Wills at Watson House or from PERA.

Crawford decided we needed a name and opened a competition to staff and families. Several good suggestions came in, but Betty came up with “HALCYON” and received the £5 note!!! (Betty was the wife of Ray which explains the 3 exclamation marks C.S.)

So at Christmas time 1948 I took a model H home to 28 Place Lane, Old Coulsdon and installed it in the grate of the back room, using a gas poker supply tube. Crawford installed a Model H in the lounge fireplace in the Hartley Old Road house and we took home thermometers and hygrometers and started recording the results of warm air heating.

(When I moved house to West Horsley in 1950, I took the Model H with me, converted to HX (flueless) and installed it in the hall of our cottage, which was from then on the warmest place in the village. This heater was in use until I left Horsley in 1959 when it was returned to the works, and had had no faults in its 10 year trial, with only annual cleaning of the exchanger tubes. It did develop a rattle when cooling down, but we knew where to hit it to stop the noise!!!)

The pattern of progress with domestic heating from then on is well documented in Crawford’s paper to the IGE. I was kept very busy improving the models, initially to beef up the unit for commercial use with a bigger fan, (Model L) which happily we were able to buy in. My balsa wood small fan was used to produce a tool for a Bakelite version, by pantograph copying in reverse. The original centrifugal fans were made by taking a strip of steel which had been punched to make an outlet louvre, rolling and fixing it round a pair of aluminium cast spoked wheels and putting an axle through the lot. Fortunately one of Crawford’s college friends owned Air Flow Development and was soon able to provide us with a professional unit.

I also spent a lot of time surveying commercial premises and usually supervising the installation of Model L’s. The first was the offices of SAS freight service in a mews off North Street at the top of Park Lane. Three units were fitted, and I believe lasted into the 1960’s. Another interesting one was a bank on Roman Road, Bow, where the heaters had floor level intake ducts but part of the output was diverted to form a hot air screen across the doorway. This may have been the first use of this now common technique.

Towards the end of this period the first major changes took place in Vincent Works. Power cuts were a very real problem in 1950 as industry began to get busier and Tommy Mattock got a licence to install a large diesel electric set, big enough to run the works and supply surplus to the grid in peak periods. This was to be installed in the basement along the Regent Street frontage, and meant that the spinners, smiths and works engineers department had to go.

Mr Burrage had retired by now and all the spinners were members of a single family, called either Strip or Pinch?. (It was Strip and Jack Strip – or more properly Glanville – Strip and his son were to provide spinnings years later for the new Sugg Lighting Company mentioned at the very end of the history section) They made a deal by which they bought all the plant and formers and took over the business on condition that they agreed to maintain supplies as and when required. They started up in Wandsworth I believe, but are now one of the major spinning suppliers in the country. The smithy was closed and all work put out to suppliers, and the engineers shop was reduced to an office and a small stores. At the same time the gap in the ground floor was rectified to a very high standard so that the sheet metal shop could be expanded .

By this time I was spending about half my day in Vincent Works, with a desk in the Works office and acting as the production engineer for the heater range, liaising with Tom Frampton on the drawings, at which stage I got to know Eric Petty, and with the toolroom on methods. There did not appear to be any formal costing system but it was possible to find out how long parts took to make. Typical of the sort of change needed was the outlet louvre. The prototypes had very elegant louvre units made rather like German Tin Toys. Each louvre had two tabs on each end which were passed through slots punched in the uprights and spot welded in place. When the Model L was introduced a tool was made to punch a set of louvres from a flat sheet saving at least an hour per piece. All the main sheets of the heat exchanger were converted from drill jigs to multiple punching and a multitude of jigs were made for other parts.

The generators were installed along the road frontage, with their oil tanks, and I think were still in use when Sugg’s left Westminster. They certainly stopped dreadful stoppages, and in hind sight were probably installed because of fore knowledge of armament orders due to the Korean war. These were about to change the situation radically.

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B.R.Sugg History 1951-1954

The beginning of 1951 saw big changes at Vincent Works following the appointment of John Fisher as Works Manager. John was a Yorkshire man, fairly dour on the surface but actually good natured. I think his background was in the automotive industry. possibly with someone like CAV , but certainly in mass production methods. He was obviously a good choice to deal with forthcoming armament orders, and to bring the whole organisation up to date I was already spending most of my time in Vincent Works, as an ipso facto production engineer and John extended my range of products to cover all gas products as a trouble shooter. I found myself dealing with incinerator timing devices, appliance governors , interlocking cocks for industrial ovens. etc., etc.

My involvement in the Halcyon was limited at this time to lunch time discussions with Crawford which involved Tom Frampton who was now taking over the drawing work. I did manage to find time to get some text books on fan design and work on the axial fan for Model L and the experimental centrifugal fan for ducted heaters.

Another change which happened about the same time was the arrival of Bert Shayler to run the foundry. He made a lot of changes to increase the potential output, one of which was to clear out the pattern stores and reduce the pattern shop to a modification role, with new work put to outside firms. Among the old patterns were many lamp post bases and a few complete lamp posts, all of which would have been very valuable to Massrealm, but one could not see so far ahead. (Massrealm was the ‘off the shelf’ name for the company that we bought in 1978 when starting what was to become Sugg Lighting – see History. CS.) I did check carefully to see if there was anything relating to the Embankment dolphins, but these must have been left elsewhere. Bert was keen on gravity die casting aluminium and also started negotiations with the Council to re-establish an iron furnace. It took several years to get this accepted in Westminster, but it was very useful when gas fire production started later.

John Fisher was concentrating on preparation for armament orders which were expected soon as the British Army was now involved in Korea. The old capstans were cleared out of the ground floor of the Vincent Street block, together with all belts, pulleys and shafts. A new floor was laid, because the old one was so saturated with brass swarf and oil that anyone in light shoes risked injury, and an assembly shop was laid out. The steatite shop was cleared out and converted to a Parts Store with a goods hoist down to assembly level. A water back spray booth and camel back oven were installed for lacquering fuses.

About the middle of 1951 great piles of ex-mothball material began to arrive from MOD. Transit trays for use during production, transport boxes, gauges, fixtures and test machines were all delivered for the first order which was for the type 117 Fuse. Later in the year flat loader lorries arrived each bearing an enormous Wickman multi spindle auto, on lease, complete with their team of engineers, setters, minders and tools. I think there were three 4 spindle units of about 3 inch capacity and two 6 spindle units of about 2 inch capacity.

These were amazing machines, probably the last stage of development of purely mechanical automation before computers were available. They were far more than lathes and could mill, drill or thread at angles to the main axis, but of course they took a lot of time to programme and needed continuous checking. They did have some automated features, such as strain gauges on tool holders to warn of blunt tools, but once up and running they could turn out complicated parts such as fuse bodies every time the spindles revolved to the next station. All very interesting but nothing to do with my own work or so I thought.

Once production started the assembly shop was staffed by about twenty girls and an approved inspector was engaged to oversee both assembly and part production. He was responsible to John Fisher for both quality and quantity of output. He was a pleasant Irishman who seemed to manage very well to start with, apart from a tendency to take a rather liquid lunch. I came in one Monday to find that he had been fired on Saturday having spent Friday night in his office drinking himself silly.

I should have explained that I had been vetted as an approved inspector during the war at Westinghouse when we were making hush-hush components for proximity fuses. So I was promptly appointed Inspector/Supervisor of fuse production and did nothing else for about 18 months, completing the 117 orders, then a batch of American fuses, basically similar to 117’s but with a delay device, and finally huge numbers of practice dummy fuses for 30 mm cannons.

Fortunately I had been used to running a team of girls during the war and the hand over was pretty smooth, despite the strong Irish connection between the girls and their old boss. (Almost all the girls arrived with work permits showing their last position as “domestic help” and last employer as a certain Doctor in Pimlico). I have always been amazed at the deep interest that young girls can take in getting the best out of a repetitive job. As an example, the key operation in the assembly of a 117 was inserting three pins into the body. Two were hinges for the shutter and the lock weight, and had to be upright and straight and all three had to be secure. They were inserted using a foot operated press, and inevitably there were differences in size of holes and pins. The girls who worked the presses got so good at feeling through their feet whether the fit was right or wrong that they saved hundreds of rejects, and were delighted when they did so.

The other job at which some of them became very skilled was operating the shutter test device. This consisted of a holder for the fuse body which could be spun at variable speed under foot pedal control, very like a sewing machine.

The operator looked through a glass cap which retained the fuse and could see when the shutter opened as a circular hole appeared in the centre of the body. A rev counter was then read and had to read between marked limits (I think 900 to 800 rpm) and the speed was reduced until the shutter closed at a lower level of about 600 t0 500 rpm. A skilled girl could do the complete test including loading and unloading the fuse in about 30 seconds. It took me about twice that time.

Working on the assembly line was hard physical work. The transit trays held 12 fuses and weighed 15 kg when full and the line was designed on the basis of passing trays from one station to the next. A transfer took place about every 10 minutes and two men porters were involved to move trolleys of trays to the lacquering station and on to packing. One of them was the brother of the actor Roger Livesey, who had exactly the same voice but was down on his luck.

The American fuses were similar in use to the 117, but totally different in construction. In place of the solid brass body of the latter, there was a steel forging about an inch long at the large end, with a small diameter tube extending to the nose and a pressed steel outer casing to form the cone. The shutter mechanism was the same in principle, depending on the spinning of the shell from the rifling of the gun to arm the fuse but there was an additional component in the side of the body including a direct passage and a diverted passage which could be selected by the gunner to set “instantaneous” or “short delay” on the firing of the main charge, to permit penetration of a target. In both fuses the principle was that when the armed fuse hit a target, the striker pin exploded a percussion cap. The flash from this exploded a charge of gun cotton in a magazine and the explosion of the gun cotton was powerful enough to fire the high explosive in the main shell.

The 30 mm practice nose was apparently a simple component, but had very tight tolerances on dimensions and weight. They were churned out at great speed by the 6 spindle Wickmans, punctuated fairly regularly by oil fires caused by impurities in the very hard aluminium alloy. As each machine held about 40 gallons of light cutting oil, the fire extinguisher system had to be pretty good and only smoke and smell resulted!!!!

The armaments work was finished about the middle of 1954, as I recall, and there followed a dreary episode of packing up all the MOD issue material, cataloguing and despatching it to be re-mothballed. I then returned to my trouble-shooter role on gas appliances, which by this time included a small but steady flow of various models of Halcyon heaters. This was sufficient to justify retaining the fuse assembly shop for heater work, and the camel back oven used for fuses was replaced by a radiant panel tunnel, probably by Bratt Colbran. New and more powerful presses were installed in the basement where the Wickmans had been and these began to contribute to the growing workload on heaters.

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B.R.Sugg History 1955 –1959

Life returned to normal by the end of 1954, but yet another major change was about to happen. At about this time (the dates should be checkable) Sugg’s took over the firm of Cowper Penfold following an introduction by Robert Young whom I believe was accountant to both companies. Cowper wished to retire and the deal involved him acting as consultant for only a few months, and us taking over all his stocks of convector heaters, Sapphire balanced flue heaters, parts, tools etc. The left hand ground floor building in Chapter Street was emptied of old cooker castings (mainly commercial designs) and filled with convector heaters in varying states of repair.

A part of the deal provided us with the services of William Symes Watts as an industrial designer. He was a direct descendent of the Victorian master painter George Frederic Watts, who is remembered by a museum and incredible chapel at Compton, Surrey, just below the Hog’s Back. A charming bloke, he was to have a lot of impact at a later stage.

We also took on George Vernon, who had been Cowper’s sales director and previously worked for Bratt Colbran. He was clearly very well connected in the gas industry and took on the task of selling the CP products enthusiastically. There was good demand for the small Sapphire heaters which were soon being added to the production range in Vincent works. They were ideal for installation in the prefab type buildings then in vogue, which could be factory-made to take the balanced flue, but the flue presented a problem in more conventional buildings. There were also problems with lighting the pilot, because as soon as the pilot window was opened, a high wind could blow out flames. Automatic lighting was really needed but I don’t think it was ever developed. George also took over the sales of incinerators and lighting, engaging some of the old staff, but the Halcyon venture was still at director level between Crawford and very senior gas Board officials and developers, and new products were needed to satisfy the sales organisation.

The product chosen was a portable gas fire, which would compete with portable electric fires with considerably lower running costs because electricity was expensive at the time, and greater reliability as power cuts were still very frequent. Many pre and post war houses had one or two open grates for coal fires and the gas boards had been very successful in selling self-sealing plug in connectors for use with gas pokers. Post war coal was often very low grade and difficult to light with traditional paper and wood sticks. There was seen to be an opening for a fire that could be stood in front of any coal grate with a gas poker socket and plugged into the socket using a flexible tube. Watts undertook the design of the product, but we had no recent knowledge of gas fire technology having last made fires in the 1930’s. Hey presto, I was re-allocated to Crawford’s department, moved back to Chapter Street, and given the job of the technical design of a new model fire.

Vernon proposed that the unit should have an output of about 1 kW of radiant heat so that with a probable efficiency of about 40% the input would be 2.½ KW or say 8,000 BThU. He stressed the need for a quiet burner, leading to selection of Bray flat flame aerated jets as used in the Halcyon, and suggested that the fire clay “fuel” should be in simple pieces, as breakages might be high in a portable fire and the complicated grids used in larger fires were expensive to replace. There were also patents and registered design problems to be overcome, unless a radical approach was taken.

Fortunately we still had the 1 metre radius semicircle which had been used when developing the Stokes Heater, and Billy Rose set about erecting this vertically, with a protractor plate with an index lever fitted to the floor and centred on a dummy grate with a flue. We could then use the BCURA radiation meters to plot and integrate radiant output over a hemisphere, as required by the “Leeds” test.

A number of burners were made to determine the best spacing of jets to produce a continuous band of glow without gaps, and I then started carving bricks out of Vermiculite blocks to determine the best fit to the flames, avoiding soot production while not losing too much glow if the burners were turned down. (In fact there was no provision made for a turn-down control, apart from fiddling with the tap on the self sealing plug-in connector.)

The structure of the fire was now agreed with Watts. There was to be a cast base enclosing the gas supply including a governor, to which was attached a sheet metal surround for the fire proper extending to a flue hood, a decorative front panel large enough to cover the average coal grate with a decorative frame round the radiants and a carrying handle. I decided that the sheet metal surround should include the burner fixings, and fit snugly round the fire brick except at the front where there would be space to drop in a series of horizontal, single bar radiants. These were the chief problem from a development point of view. I fear I made as much use of industrial espionage as I could, finding the name of the actual manufacturer, Taylor Tunnicliffe, and acquiring samples of existing designs. It was the actual making of samples for test which was so time consuming but essential, as Taylor Tunnicliffe although very interested to have a new customer could only produce from expensive moulding tools.

So I became a potter. From balsa wood models we constructed rubber moulds of the main triangular section, open at the back. These were then filled with potter’s clay (bought from an art shop in the King’s Road), dried off at room temperature and lifted out of the moulds with a high rate of breakage. A thin triangular strip of clay was cut into small sections to form the “teeth” that were to project into the flame zone on the back of the bar and attached at various spacing using potter’s slip.

After more drying the bars were fired up to the highest temperature achievable in an old oven. Most of them bent or twisted and it took days to prepare a set to fill up the front of the fire. It was not unexpected that the presence of the bars altered the air flow and required change to the back brick design, but after only a few changes we had a good looking radiant unit of about 35% efficiency. When we had professional bricks and TT fire bars we got very close to the planned 40% output. Prototype casings were hand made and complete working samples demonstrated.

Christened the “Screen” fire and attractively finished in 1956 style bronze paints of various hues, the Gas Boards liked what they saw. There was a lot of tooling required, as we had no press large enough to make the panel, which I think was produced by a firm called Fletchers in Birmingham Our foundry had to make moulds for die-casting the frame and base, and Bert Shayler brought on line the iron furnace which he had been constructing

One early problem was getting a consistent anodised colour on the frame round the elements, which was too hot for stove enamel finishing. The answer was to use only virgin ingot HE10, discarding runners, etc., which were mixed in the normal casting melt for making bases. We also had to get approval of the fire-guard, surface temperatures and stability from Watson House. Nowadays I am quite sure that the concept of a fire with no safety devices to shut it down if knocked over or carried would never be accepted nor the fact that only a label told the user to get the flue hood close to his main chimney.

But the 50’s were less safety conscious and the fire sold like hot cakes. The paint shop had to be further extended and Vincent works was beginning to look full. I don’t know how long the “Screen” continued to be marketed, but you can probably find out. I doubt if it was ever converted to natural gas.

The larger “Sapphire” had been redesigned by Watts with attractive gold grills and had started to sell well. There is a photo in the I.G.E paper. Unfortunately they were proving expensive in warranty terms as technical faults were developing due to internal corrosion and I was asked by Crawford to investigate. An examination of a few samples showed that the problem was condensation collecting within the gas chambers and rotting the spot-welds in the bottom seam.

Attaching a lot of thermocouples revealed that there were cold spots in the corners of the heat exchanger where the hot gas flow was reduced. The large units had been designed by geometric expansion of the very successful small unit and made in the same gauge of galvanised steel sheet. Probably the gas flow pattern had changed or the heat transmission through the sheet was inadequate to heat up the cold spots. Thickening the gauge of sheet was tried but without success and the provision of extra baffles to deflect hot gases into the corners also failed to improve matters very much.

Fundamentally the problem was corrosion round the spot welds allowing penetration of the chambers and ruining the balanced flue performance. The Zinc coating on the steel sheet was vaporized locally round the weld by the welding temperature leaving an unprotected ring of steel, which corroded quickly in the acid condensate which occurred from the burnt gases. We experimented with various variations in welding method without much success, and it was largely by chance that I read an editorial in a trade journal which mentioned work being done on aluminium coating steel. This was very interesting because the vaporizing temperature of aluminium was more than twice that of zinc, in fact over 2000 degrees C and the electro chemical action between aluminium and steel was the reverse of that between zinc and steel.

Following up this editorial lead me to a small company in Bridgend and I obtained a few small samples from them. Testing trial welds to destruction confirmed that there was little loss of protection due to temperature round the spot, but the quality of the coating and its variation in thickness were matters of concern. I had acquired a plating thickness meter while testing the cadmium plating on the bodies of American fuses, a simple magnetic device, and I arranged to visit Bridgend to see if I could find out more about the process and plant.

I found a young, recently retired naval engineer officer who had set up a small dipping plant in an unused ex-British Steel with their blessing. I was the first potentially long term customer who made contact and he welcomed me with open arms. I was able to show him the faults in his product and to suggest that he had to introduce better temperature control on both steel and aluminium and probably look at fluxes to stop oxidation of the surface of the aluminium and I suggested PERA and BISRA for technical assistance.

He had backing from British Steel and other customers turned up, and within a few months he was sending us good coated sheet in usable sizes, with which we got over the warranty problems with the Sapphires.

By 1957 the market for the Screen Fire was beginning to flag and the need for a larger fire for fixed installation was recognised. To be competitive, this had to be a convector fire of high efficiency so I started work on what became the Queen fire The radiant section was an expanded version of the Screen Fire, to give 2 Kw radiation, with another 1Kw to be convected air output and an input of 4.1/2 Kw, giving an overall efficiency of about 66%. The radiant section was much quicker to design than the original Screen fire, because Taylor Tunnicliffe had now realised that we were a serious player in their field and gave much more assistance with the radiants. However the convector heat exchanger design presented a number of problems as we had to consider air breaks to suit both old style fireplaces and modern flue systems. I was surprised to find that it was easy to produce a condensing flue system, which of course was not practical and the final design was quite compact and fitted nicely into a case which Watts had designed. I am not sure whether the Queen fire went into production at Vincent works, which by 1957 was buzzing with Halcyon work, but it certainly made its mark after the move to Crawley.

By this time Crawford was deeply involved in the FSD Halcyon, but apart from lunch time discussions over a sandwich and sketches I had no role in this development, being very much engaged in production problems of the earlier model and ducting.

During 1958 it was learnt that Westminster Council had decided to rezone the area round Vincent Works as residential and that a compulsory purchase order would be made. In return a new factory was to be built in Crawley New Town (then very new) and assistance provide for re-housing staff who wanted to move to the new site. At the same time I was getting into financial difficulties, as my salary had been too slowly increased to keep up with my living expenses, particularly school fees.

Philip was then eleven and at Downside School which was not cheap even then. The school was really planned to prepare pupils for the 13 plus Common Entrance exam but could also use the 11 plus exam for state schools. However, there did not seem to be a good state school available from Horsley. We were outside the catchment area for Guildford Grammar and alternative grammar schools involved excessive travel. An official visit to Crawley to see the new factory under construction and the housing and school facilities did not fill me with enthusiasm, and it was clearly not possible to commute to Crawley from Horsley. Clearly I had to take drastic action and I started to job hunt.

By early 1959 I had three offers. The most glamorous was as a junior consultant with PA Group, which offered £2,000 salary, but involved changing projects and moving every two years or so, so not good for schools. The second was as a consultant in production automation at PERA, which would have been very interesting, but I had doubts about the stability of a Government funded organisation which turned out to be well founded a few years later. The third was the post of works manager in a small instrument company in Abingdon at a useful increase in salary and with the promise of a directorship after a period. I liked the people I liked the town and Abingdon School was keen to take Philip at 13 and was a Direct Grant, affordable school, very much like Whitgift but with some boarders.

I took the job, left Sugg’s at the end of April 1959, took my pension fund to clear my debts and buy a 4 year old Ford Popular, placed Philip in a small private school for a year to prepare for the Common Entrance exam which he passed with flying colours, found a new bungalow near Oxford with Halcyon Heating already installed (curiously the developer was named Christopher Sugg, but I never actually met him) and started on my new career.

My time at Sugg’s had been wonderful training for future management but unfortunately it seemed unlikely that a suitable post would occur within reasonable time if I stayed there. As it was we regretted having to leave our cottage in Horsley but everything else was an instant improvement in life style, so none of us ever felt we had made a mistake. The experience gained at Sugg’s fitted me admirably for my new role, involving product development and production management almost equally, but also business management at director level and my career developed very well.


I would like to record my thanks, albeit posthumously, to my father Crawford Sugg for the first piece on the development of the Halcyon warm air heater inspired by the loan of a small warm air fan heater to keep me warm in my nursery!

Secondly and also sadly posthumously, to my uncle Raymond Sugg for his very descriptive piece about his time at Sugg’s in Westminster. I have to say that both my father and Ray were gentleman in the true sense of the word and neither would ‘blow their own trumpet’. Consummate and born engineers they had a natural ability to communicate and inspire confidence and trust from their staff. After his time at William Sugg & Co., Ray Sugg became a world expert in anaesthetic gases and their delivery systems which are in use everywhere and, as he says at the very end of his piece above, ‘my career developed very well’!

The family miss you both.
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In June 2011 I received the following note from Cliff Summers who worked for one of the first warm air installation companies, ‘Griffin Warm Air’, which gives you some idea of the huge excitement that the development of the Halcyon produced in the building and gas industries:

Hello Chris,
I don’t know if you will remember me, Cliff Summers, I worked for Griffin Warm Air from the mid 60’s to the early 70’s and had a good business relationship with Wm.Sugg particularly when I opened up and ran the Office in the Northwest based near Warrington.
I was ”browsing” the web and to my delight found your fascinating website, which I have just dipped into but will read in detail, my compliments on the work which has gone into constructing the site.
During the period I was with Griffin we were in the middle of the 60’s housing boom and following the advent of the Parker Morris standards being implemented the sales of domestic heating, particularly warm air, went through the roof.
My local sales representative was Sid Whitehead who was a charming and hardworking rep and we worked closely together with great success in the Northwest Gas area. The high spot was an order from Geo.Wimpey for the biggest individual development for Liverpool Council, which was for a total of in excess of 2000 heating systems in one phase at Netherly site, 1270 were for 22WH operating on the newly developed ”U” duct, a variation of the SEduct and the remainder were conventional flue 22WH for the low rise housing surrounding the Deck Access mid rise blocks.
At the time this was the largest individual order placed with Wm.Sugg for warm air heaters and as an astonishing coincidence I also picked up an order on the same day for 600 Sugg units from Fram Ltd for a high rise development on the outskirts of Liverpool. I therefore had the sheer pleasure of handing two big orders to Sid the following morning, as you can imagine his face was a picture.
Sid promptly rang George Vernon with the news and George immediately spoke to Crawford and the two of them travelled up to Manchester the following day and we all had dinner in the French Restaurant in the Midland Hotel, a very memorable, if somewhat blurred event. Crawford, being as always the complete Gentleman retired fairly soon after the Port started to circulate, with the memorable statement that ” I will leave you youngsters to play”, which statement included George !! (George Vernon was the long time sales director of a similar age to Crawford! C.S.)
I have rambled on a bit but most of my memories of Wm.Sugg are happy ones and it was sad that Thorn took the company over much later and along with International Janitor, Smc circulators etc proved quite conclusively that big is not necessarily beautiful or efficient or desirable by eventually totally losing the plot.
I look back to the housing/warm air boom of the 60’s and can quite clearly see with hindsight that all of us youngish men did the warm air industry no favours by selling down to a price and of necessity installing cheap systems that eventually gave warm air a very poor reputation, but that was the way at the time and we did sell a hell of a lot of systems.
I am now retired and living in France, I note that you also are retired so I hope you are enjoying life to the full, as we are. Many thanks for the pleasure of your Website.
Kindest regards…….Cliff Summers




Copyright © Chris Sugg 2006-13

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8 comments on “Warm Air Heating
  1. Myron Horobin says:

    I certainly remember Sugg Halcyon Heaters. I was an apprentice draughtsman
    working for Heatinaire in 1960, when from memory Sugg , Radiation Ductair and our company were the only ones in the Warm Air Industry.
    Ialso remember Cliff Summers at Griffin Foundry in Birmingham, although he would more likely have come into contact with the area rep Peter Birmingham
    who used to work at Roman Heating before joining Heatinaire.

    • Chris Sugg says:

      There were several companies that joined the warm air revolution including International Janitor. Suggs were eventually taken over by the Thorn organisation that also bought IJ to make what they called Thorn Heating and moved everything to Co.Durham resulting in the loss of all staff who had found it difficult enough to move from Westminster to Crawley! What a waste of a company that had already achieved 132 years as a company and another 30 years or so since Thomas Sugg had made that first gas pipe for the demonstration of gas lighting in 1807! Thanks for having a look at my website. It just seemed right to record as much as possible of what was an important Victorian company which grew alongside the gas industry and nowadays is till best known for gas lighting despite the later warm air heating and introducing the low water content gas boiler!

  2. Myron Horobin says:

    There were many closures and takovers during the sixties and seventies, Crane ltd took over Heatinaire, I eventually worked for Speedaire Supply who acquired
    Lincoln Warm only to be bought out by IJS a division of Thorn Heating Ltd.

    • Chris Sugg says:

      Hello Myron. Yes, it was a bad time for many old established companies. When I decided to start again after the Thorn takeover, the boss of the company who bought the factory that was vacated by the then Thorn Heating where we were located at that time was so upset about famous historic names being swallowed and lost to the world that he let us set up our small workshop in a section of his new factory and ‘keep us warm’. In due course they were able to pass on a factory that they rented because they could move into their new factory and we took on what was our first ‘own’ factory. It wasn’t until the 3 day week that we re-started making gas lighting and it caught the imagination of the TV and papers so accelerating our progress. Our agreement with Thorn only prevented us using the Sugg name for the incinerator that they did not want and any heating appliances – so we became a Lighting Company and called it Sugg Lighting! The beginning of a new history!

  3. Helen says:

    Hi Is it easy and straight forward to remove an Halycon system?

    • Chris Sugg says:

      Helen, Depending upon the model it will vary somewhat. The earliest models like the F45 will supply warm air directly from the outlet which is a couple of feet above floor level and may or may not have some 10″ x 10″ ducting through to one or two other rooms. All the later models blow downwards into a plenum chamber which then distributes warm air under the floor to outlet grilles either in the floor or at low level in the rooms.
      Apart from disconnecting the gas and electric supplies and the chimney, the unit itself can be disconnected from the ducting and removed. The ducting is often left under the floors. The later models had 12″ x 6″ steel ducting and was often installed before the floor was laid so not easy to remove without lifting the floor surface! You may be able to get a replacement unit that will fit directly on the existing duct base.

  4. Ron Stokes says:

    I am writing a brief history of Direct Fired Warm Air heating from when the first Canadian Perimeter system was introduced. I fully appreciate the work done by Crawford Sugg (who I knew through SBGI meetings) and Dr. Davidson of Radiation. and I would like to thank you for all the information on your webb site.
    I was Lincoln Furnaces first Rep in 1959 when they first started and finished up as Technical Sales Manager.

    • Chris Sugg says:

      Dear Ron, how nice to hear from you! Your name rings a bell. You realise that Crawford was my father and he and his brother Ray were responsible for the earliest Halcyon development just after the war on return from active duty. If you need any additional information do let me know and I would be delighted to read your brief history when completed. I sit on the CIBSE Heritage Committee and I know they would be delighted to add any historic information to their vast heritage website.
      Kind regards, Chris

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