Advantages of coal heating outlined

Press, Volume CXI, Issue 32587, 22 April 1971, Page 24

Advantages of coal heating outlined

Developments in home heating, using coal, have brought wonderful changes, and coal offers one important advantage: where cost is the important factor coal comes back into the reckoning—the basic fuel cost is low and with reasonably efficient appliances the price of the useful heat can be the lowest obtainable. '

Coal offers other real advantages in home heating, like these: The fire ventilates, as well as heating. This is the result of air being pulled through the fireplace, the room and the house. The importance, of this is becoming more and more apparent, as modem houses built without a fireplace have troubles because of mould formation and mildew caused by a lack of this ventilation. The fire can do more than heat a room. The other most common function is the heating of hot water for domestic supply and even for a hot water radiator system. The fire has some indefinable attraction, providing a focal point in a room, the cheerful glow providing some friendly comfort and company. Perhaps the most important feature is the individaul personality which can be given to a room by the surround of brick, decorative cement bricks decorative schists and stones. Everyone will at some time have been impressed by a complete wall of stone, offering variation and distinctiveness in ' room design, so important in the modem, stereotyped house. Solid fuel appliances can use a variety of fuels available from various sources. They can use also ; all these fuels and they can use also mixtures of, them, at different times to satisfy different conditions.

The fire is a convenient method for disposing of

rubbish and for generating some ■ heat from this waste product. A wide range of appliances and of types of appliances is available from several manufacturers as described later. The choice of a domestic appliance is often a personal one, involving all sorts of factors—such as price, installation cost, running costs, frequency of use, duration of operation, the design of the .room, and, simply, personal preferences and prejudices, tastes and habits.

Fuels and fuel supply The most common solid fuel is of course coal, but wood, coke and carbonettes are also available from coal merchants. Packaged coal has improved coal deliveries considerably. Packaged coal is now available from groceries and service stations, generally in 281 b bags. With larger packages the cost of packaging will be reduced without any loss in convenience in deliveries.

As man learned to control combustion and as his knowledge of building matured, he began to produce a crude form of the open fire we have today, in which the heat from the fire is radiated into the room and the products of combustion are carried from the room through a chimney.

The original open fire was an inefficient appliance—in many cases less than 20 per cent of the heat of the fuel ended up as effective heat in the room. Gradually the grandfathers of the grandfathers of .today’s technologists leamt about the combus-

tion process. They learnt the need to limit the quantity of air flowing up the chimney —although these excessive air flows ensured adequate ventilation and prevented any stuffiness in the room, it meant that too much heat was being carried from the fire up the chimney. Low efficiencies meant not only an increased cost, but also that more effort in the frequent tending of the fire was needed. So fireplaces were developed so that the flow of air up through the chimney was restricted and the thermal efficiencies rose. Efficient combustion Still the traditional form of the open fire persisted, but always there was the demand for more efficient combustion—grates were sealed at the front to control the air drawn into the burning coal. The convector type of fireplace was developed where the air from the room was drawn into the appliance through grills and heated by contact with the cast-iron surfaces which contained the fire. Efficiencies rose to 45 per cent-50 per cent without any loss of the traditional concept of the open fire.

Slow combustion stoves or closed stoves were developed, either built into a fireplace or as free-standing units, and thermal efficiencies increased even further. These closed stoves often have windows of heat resistant glass: the cheerful glow of the fire is visible, and the fire retains its charm as the focal point of the room. Modem developments incorporate a simple form of downdraught combustion, which,

without detracting from the idea of an open fire, gives even higher thermal efficiencies and relatively smokeless use.

With most domestic appliances a back boiler can be fitted to provide normal requirements of hot water for a home and to reduce the winter demand for electricity A most interesting recent development is a waterjacekted fireplace from which the hot water is pumped through a smallbore system to radiators throughout the house. In this way the benetfis of central heating are obtained at relatively low capital cost, again without any loss of the traditional effect of the open fire.

Further new developments

Again, other units have been developed, generally on a larger scale, for the supply of hot air. These units work silently to produce hot air either at the appliance or through a ducted system for central heating. In these units there is no visual evidence of coal burning as there is in most domestic coal appliances. Only a steel cabinet, which could be any form of heating from its appearance, can be seen.

The gradual development in coal firing has changed the face and the shape of coalfired appliances. The coal industry realises that progress in the further development of improved appliances still depends on the continual evolution of new ideas and of new designs.

New Zealand coals have unique properties, and, if full

; advantage is taken of these properties, lend themselves > to clean and convenient use ■ and to automatic control probably better than any ' other coals in the world

The coal industry realises that coal firing is just as good as the appliances in which coal is burnt. For this reason, modem coal-fired appliances offer great advantages in convenience and continuing advantage of economy.

(From the information and press section, publicity division, of the Coal Districts Welfare and Research Council.)