in thousands (say 5) by the calorific value ) ; THE BUILDING—ITS WARMING AND LIGHTING 95 in B. Th.U. (say 500) and divide by 100,000. Thus, 5000 cubic feet at 500 calorific value _ 5000 x 500 ~ 100,000 District Heating. District heating offers many advantages from the national economy point of view and not a few to the local com- munity and the individual consumer—thus: National Advantages 1. Fuel can be consumed more economically in a central heat production plant than in a small private boiler or an open grate. 2. The large plant can be designed to burn a poorer grade of fuel. 3. Coal stocks can be conserved. 4. Plant could be more readily adapted to use new forms of heating energy (such as atomic power) than the small private plant. Local Advantage. 1. Much of the smoke and fog nuisance, quite a lot of which is said to be produced by our wasteful habits of burning bituminous coal in open grates, would be reduced. 2. The rapidly dwindling stock of building land in our urban areas would, to a small extent, be conserved, since a central district heating station takes less space than scores or hundreds of smaller boiler houses—though admittedly this advantage is likely to be felt very gradually, as rebuilding was carried out making full use of the space previously occupied in this way. Advantages to the Individual Consumer. 1. Greater comfort in living conditions. 2. Hot water on tap in any quantity day and night. 3. Warmth all over the house or building day and night, with complete control. 4, Saving in labour. 5. Saving in ash and dust. 6. Saving in decoration. <Callout type="tip" title="Efficiency Tip">The use of a central heating plant can significantly reduce fuel consumption compared to individual boilers.</Callout> Pare The disadvantages are mainly a matter of exploitation of the possibilities: to pelt ae ca 1. The capital outlay in buildings, plant and distribution mains is high and the task of persuading consumers (already provided with reasonably satisfactory hot-water and warming facilities) to accept the district supplies in economic numbers is likely to be wellnigh insuperable except where big landlords or local authori- ties are opening up new estates with these facilities incorporated in the scheme. = 25 therms. 96 THE BUILDING—ITS WARMING AND LIGHTING 2. The cost of the facilities offered—while very low for the advantages of constant hot water and all-over-the-home warmth, day and night—will certainly be higher than the cost of an occasional kettle of hot water and a single living room warmed for a few hours a day by open grate or kitchen fire which so many small householders “enjoy” at present. <Callout type="warning" title="Cost Warning">District heating may not be affordable for all, especially those with existing satisfactory heating solutions.</Callout> There is no doubt at all that the householder would get very good value for money— if he can afford the luxury. Students interested in further details of District Heating might well obtain the report on District Heating by the Heating and Ventilation Committee of the Building Research Board, vols. 1-6 at 17s. 6d. from H.M.S.O., or articles on specific District Heating Schemes in various professional journals.
Development of the Open Grate. Dealing in rotation with the various available methods of warming, we find mention of iron grates for burning coal occurs in inventories of the early sixteenth century, and at the end of that century we know that the depth and width of the hearth recess was much reduced and the mouth of the flue contracted. An Italian architect, Seammozzi, writing at that time, also says that, in England, a door of iron is used to partly close the flue after the fire is well lighted, this being the first mention of the register plate. About 1624 a French architect, Savot, further reduced the height and width of the fireplace opening and introduced the iron back and covings, together with the perforated base plate of the ordinary grate still in use. About 1738 came the use of fixed canopies, adjustable registers, and the insulation of the grate by means of air spaces behind it. In the same century the well-known Bath fireplace was in vogue, consisting of a hobbed grate with an iron plate front, having an arched opening in it. It had great draught- creating powers, carrying off all the air in the vicinity. An old English writer, in commenting on it, says, “whoever, impelled by the merciless severity of the frost, comes near the grate, will find his front fried and his rear frozen”’. At the beginning of the nineteenth century, Count Rumford, a versatile American, at various times shop-boy, soldier, diplomatist, financier, scientist, and founder of the Royal Institution in our own country, did more to improve the fireplace than anyone up to that time. He it was who brought the fire grate forward, the mantel lower, emphasised the importance of forming a “throat” to the flue, and introduced the diverging sides and covings to obtain greater radiation of the heat into the room. He pointed out that the bars should not be too far apart, ensuring brightness THE BUILDING—ITS WARMING AND LIGHTING 97 of the exposed surface of the fuel and increasing the radiation of the heat, and that dull, rough, iron covings were better radiators of heat than polished surfaces.
Dr. Teale’s Experiments. Later in the nineteenth century, valuable experimental work was done in connection with the im- provement of fireplaces by Dr. Teale, F.R.S., who embodied his conclusions in a paper read before the Royal Institution in 1886, on “The Economy of Fuel in House Fires”. The chief conclusion obtained by Dr. Teale was that slow and efficient combustion depends on there being no current of air up through the grate, and he accordingly introduced what is known as the economiser, shutting in the space below the grate. He also laid down a series of rules for the design of fireplaces, the principal of which are: 1. Use as little iron as possible, making both back and sides of fire-brick. 2. The fire-brick back should lean over the fire; and 8. The greatest efficiency is obtained from the covings when they are inclined at an angle of 60° to one another. To these might be added the need for a controlled draught, a throated flue and a good chimney capped by a clean-cut pot, clear of obstructions and free from the blanketing effect of high buildings or trees in the vicinity, which might cause a back pressure or down draught.
The Sunk or Well Type. Later investigators have held that it is important that the air should not pass through the face of the fire, and so have designed fireplaces of what is known as the sunk type with raised hearths in front and ventilating fenders communicating with a hot-air chamber below the grating at the base of the fire, practically the whole thing being formed of fire-brick. In some examples the base of the grate is formed with reinforced fireclay bars to prevent the absorption of heat by the iron. i Other experts hold that there is no necessity to supply air to the lower side of the fire and that a grated base with an ash-pit under is a superfluity. It has been fairly well demonstrated that a good fire can be obtained without any air supply other than that passing over the top of the fire; that more perfect combustion is thereby attained with economy of fuel; and that much less draught is caused in the room owing to the demand for air being far less than in the older types of grate. It should be pointed out, however, that, in almost all types, ashes will accumulate and require removal. The grated base allows for the removal of the ashes without letting out the fire, which is a point not to be overlooked in the case of a sick-room | 4—D.S. 98 THE BUILDING—ITS WARMING AND LIGHTING where a fire is constantly required, while another advantage is that the fire, when newly ignited, can be “drawn up” more quickly if air is allowed to pass through the burning fuel. As soon as the fire has burnt up sufficiently, the damper (if one is provided) can be closed and the fuel will then burn more slowly with the air supply from the top only.
Care must be taken that open grates of this type are not placed on a hearth with timbers under or in too close proximity. Fig. 81 shows a “slow-combustion” grate of the sunk type. The fireclay base is in three pieces, the central portion being sunk to form a well; the upper side of the base is at or about floor level. The upper part of the grate is of fireclay, moulded in one piece, with its back leaning forward to reflect heat towards the floor and with its sides diverging outwards to reflect heat into the room. A modification of this has a flat hearth with a loose and movable stool, standing on three or four dwarf feet, sometimes (in the larger sizes) provided with wheels. This gives excellent control of fuel consumption, as air can be admitted through the bottom of the stool when the fire is first lighted whilst, when it is desired to slow down the consumption, the fret can be pushed in to stop the through draught and the fuel will burn more slowly, as in the case of the sunk type.
The Coal Utilisation Council. Some mention must be made here of the Coal Utilisation Council whose signs, ‘‘Authorised Solid Fuel Appliance Service” and “Coal Merchants’ Diploma Service” (in a circle with black-and-white diamonds over it), are to be seen in practically every town in the country. The council has not only made a careful study of the use of coal and its derivations and made their knowledge available to the public, but has also instituted a training service enabling the staff of shops and stores marketing solid fuel appliances to learn the principles of design and construction of grates and stoves for different purposes. It has done the same for the staffs of coal merchants so that they may be able to advise the public as to the best fittings to purchase and the most suitable fuel to burn in them.
Continuous Burning Open Grates. The main points they em- phasise in the design of open grates are the close control of air THE BUILDING—ITS WARMING AND LIGHTING 99 supply, and the easy removal of ash from the firebars into an ash tray, where it may be removed by the housewife without scattering dust about the room. The council does not issue a standard specification like the British Standards Institution, but manufacturers of these appli- ances can submit their designs and models for approval by the council and if found satisfactory they can be put on the market with the seal of the council’s approval. Most of the open grates sponsored by them are vitreous enamelled for easy cleaning, bolted down to the hearth and sealed up with fire-cement everywhere except where the air supply is to flow by design. The lower part of the front (taking the place of the sliding “feet” in older models) is machine ground where it fits against the body of the stove, the air supply being controlled (often foot-operated) either by a sliding shutter, a hinged trapdoor or screw-controlled circular inlet. Other sponsored models are “self-contained” so that they can, if desired, be moved from one room to another, without the bolting down or the need for the fire-cement sealing process. Most of the bolted-down models can be provided with gas ignition if desired and some are designed to work with a back boiler to replace or to augment the range boiler or the independent boiler in small houses. Nearly all open grates of this type are designed to burn with a bright fire all day and with a slowly-burning fire at night by nearly closing the air control and loading up the fire with small coal. An extra inch or two of front is usually added for night burning as a safeguard and to hold the extra fuel for long continuous burning without attention.
Convection Types of Open Grate. Models which include the Galton System of air warming (either for circulating warm air in the same room or for background warmth in the room or rooms above) are also sponsored by the Council—generally known now as **“Convection”’ models. Reference should also be made to the “Plumbing Unit” de- scribed in Chapter VII which also makes use of the Galton idea.
Closed and Openable Stoves. “Closed” and “‘openable” stoves to burn anthracite or semi-anthracite also come under review. These are either of “built-in” type or are “freestanding”. The freestanding model is not really portable, but stands on the hearth in front of the fireplace opening, with a short length of stove- pipe at the back taken through an iron or asbestos-cement panel which fills and seals the fireplace opening and prevents uncon- trolled air currents passing. ' The student is advised to compare the different makes and 100 THE BUILDING—ITS WARMING AND LIGHTING types of open fire and closed stove which he will find in his own and his friends’ houses and also in the showrooms of builders’ merchants and others. There is considerable prejudice, in some quarters, against the use of closed stoves in this country, as people want to see the fire. The older forms were apt to get very hot, and they roasted and burned the organic matters in the air, giving off unpleasant odours. They were liable to decompose the air and they certainly deprived it of much of its moisture. The average type of closed stove gives less help to ventilation than the open grate. The following extract from the works of an old writer, Jeremy Bentham, is an amusing commentary on the man- ners of his time: “‘ A bad smell often arises in consequence of people spitting on the stove to try if it be hot, but his nasty, unmannerly practice should be reckoned to the discredit of the spitter and not as an objection to the spitee.”’ With closed stoves there is some risk of the escape of carbon monoxide, so all the joints shall be carefully made, particularly in the ‘freestanding’? models, where the short lengths of flue emerges at the back and passes through the wall or sealing panel into the brick flue. Both the freestanding and built-in models are usually lined with fire-brick and cased with vitreous-enamelled iron, having inlet and outlet air-frets, so that the air of the room can enter the warm air chambers, emerge at the upper openings and circulate around the room by convection, To make the appearance more cheerful, mica panels are usually put in the front fire door or doors. In the “closed” type there will be only one such door, hinged on one side only, but in the “openable” type, there will be two smaller doors opening out flat, when of course the fuel should be changed to a more free- burning type such as Coalite or semi-anthracite or even to ordinary house coal. When closed and used with anthracite, these stoves are very labour-saving as, with care, stoking can be done about twice in the 24 hours and ashes can be raked out by an outside handle, without getting dust out into the room. Stoves of this type are usually very economical.
Air-heating Stoves. The ventilation provided by stoves of the type just described is not so good as with the open grate, but this disadvantage is sometimes offset by bringing a fresh air conduit to the base of the stove as shown in the next example, Fig. 84, which gives a diagrammatic section of the ‘“Musgrave”’ stove, which is closed in. The sketch shows it with a back outlet for THE BUILDING—ITS WARMING AND LIGHTING 101 smoke, but the descending flue can be used carried under the fivor to the nearest wall capable of carrying a flue. The stove is lined with fire-brick, shown by hatched lines, and the iron work is shown throughout by thick lines, the dotted lines indicating grating out- lets for warm air. Oil Heaters. Oil stoves for heating the houses and other build- ings do not need very serious consideration, except for use right away from such public services as gas and electricity supply com- panies can give. Oil heaters usually burn refined paraffin—some with a wick. others wickless. In some the heat is radiated by a parabolic reflector. In others it is distributed by convection, the air passing through and over the heated surface of the container, or, again, the flame may be placed under a tiny boiler at the base of a hot-water or steam radiator. Oil heaters are economical in theory, since the whole of the heat produced is passed out into the room. They are usually very portable and are sometimes used for warming up rooms needed only occasionally, even in houses having all the advantages of the town. They have the disadvantage, however, that all the by- products of combustion pass into the air of the room. There is a good deal of trouble entailed in filling, cleaning, trimming, etc., rather more risk of fire than with most other methods of warming, and very unpleasant effects if the cleaning is neglected or the adjustment of the flame is mismanaged. Refined paraffin is expensive as a source of heat, so that the oil heater’s claim to economy is more apparent than real and can be substantiated only in eases where warmth for short periods at a time is needed.
<Callout type="gear" title="Recommended Equipment">For those considering district heating, ensure compatibility with existing infrastructure and consult local authorities or landlords.</Callout>
Key Takeaways
- District heating can offer significant economic benefits but may be unaffordable for some households.
- Open grates have evolved over centuries to improve efficiency and reduce smoke emissions.
- Closed stoves provide a more controlled heat source but require careful maintenance.
Practical Tips
- Consider district heating as an option if you live in a densely populated area where it is available.
- Regularly clean your fireplace or stove to maintain efficiency and safety.
- Use the appropriate type of fuel for your open grate or closed stove to maximize performance.
Warnings & Risks
- Be cautious when using oil heaters, as they can be dangerous if not properly maintained.
- Ensure proper ventilation with any heating system to avoid carbon monoxide poisoning.
Modern Application
While the specific designs and materials have evolved since this manual was written, the principles of efficient fuel use and safe installation remain crucial for modern survival preparedness. Understanding these historical techniques can provide valuable insights into sustainable heating solutions that balance cost-effectiveness with environmental impact.
Frequently Asked Questions
Q: What are the main advantages of district heating over individual boilers?
District heating offers several advantages, including more efficient fuel consumption, the ability to use poorer quality fuels, and reduced smoke emissions. It can also help conserve coal stocks and be adapted for new forms of energy like atomic power.
Q: How did Count Rumford improve fireplaces in the 19th century?
Count Rumford introduced a lower mantel, emphasized the importance of forming a ‘throat’ to the flue, and added diverging sides and covings to increase heat radiation into the room. He also noted that bars should not be too far apart for better brightness and heat radiation.
Q: What are some disadvantages of using open grates in modern homes?
Open grates can be messy due to ash accumulation, require careful placement on hearths, and may not provide as good ventilation as closed stoves. They also produce more smoke and can be less efficient.