Fireplaces Have The Same Magnetic Quality

Press, Volume CVIII, Issue 31657, 18 April 1968, Page 22

Fireplaces Have The Same Magnetic Quality

Since the earliest times, when man found the use of fire to warm and comfort him, to our present-day modern and sophisticated methods of home heating, the fire has always been the centre around which people gather to relax and enjoy each other’s company.

Fireplaces, be they just a hole in the wall, or some ornate Adam masterpiece, have that same magnetic quality, one filled with burning coals which throw their flickering shadows, hissing and sighing as if trying to induce contentment into all who gather to enjoy their warmth.

shaped homes. There are four other methods, apart from the open fire, which come within the solid fuel range and these will be discussed separately. 1. The open 'fire convector. 2. Closed fire convector or space heater. 3. Stove or destructor. 4. Central heating. Remember that all these appliances can also be fitted to supply hot water. All the above have different initial costs and running costs but, before looking into the different types available, let us consider the basic requirements of our individual heating. If an open fire is a “must” in the lounge, then the choice is restricted to an open fire or open fire convector with a destructor in the kitchen to serve the need for either domestic hot water and perhaps background heat for, say, the hall. If this dual purpose is desired, then an indirect cylinder is essential. However, if warm air circulation is accepted, it is possible to install an open fire convector in the lounge and warm air can be ducted to the dining room, leaving the destructor for providing domestic water only and saving the cost of an indirect cylinder. Finally, it may be that central heating is desired and possibly an open fire for appearances sake. If this is so, then some arrangement could be made to fit the chimney with a damper to close it when not required. It is fairly elementary to assume that, if possible, the appliance used should be situated as centrally as possible within the area to be heated, both for convenience and efficiency. The value of insulation is not always appreciated by the public but can be over-empha-sised by the salesman. However, if you consider what duty your appliance fulfils, some idea can be gained of the amount of heat that can be saved. More than one-third of home heat is dissipated through the roof—so it is often stated that fuel bills can be cut by more than one-third by using insulation. This is probably correct for an appliance used specifically for space-heating, but if a heater is used solely for domestic water heating. no amount of roof insulation will save money on the fuel fed into it. However it is only logical to conserve the heat we generate and pay for and roof insulation will serve a dual purpose of conserving the heat in the winter and keeping the interior of the house cool in the summer. The Open Fire Convector gives one the psychological satisfaction of the open fire and supplies warm air at the same time. Air is taken from the room and recirculated through a heater box back into the room again. Some models are designed to heat and circulate fresh air from outside the house, providing a change of air within the room. Although not

quite so efficient as the true space heater, these models are more than twice as efficient as the open fire. Another step forward, and at an estimated 40 per cent efficiency, we can now enjoy 64 cents worth of heat from our $1.40 bag of coal. Again, any coal is suitable, but with slower coal successful banking can be achieved for long periods. Essentially, these units perform the same function as the open fire convector but are totally enclosed, the fire being viewed through hardened glass doors. This type of unit ensures strict control of the burning-rate and, in some models, provision is made to duct air to an adjoining room so that partial central heating is achieved. Some appliances of this type may be built into existing fireplaces and others are freestanding, the products of combustion passing through a flue before entering the chimney. Any trouble that might occur in this type of installation is invariably traced to faulty sealing, for it is essential that draught conditions are not broken by leakage. However, a reputable firm will give every advice and assistance, and take every precaution to preclude this happening. Wet-backs are a feature of some models, and one has a noiseless fan to assist the circulation of air into the room. A down-draught principle employed by some manufacturers directs any smoke that is produced through the incandescent zone over the fire, effectively consuming it, and practically eliminating any smoke to the chimney. Efficiencies of approximately 60 per cent are now giving 84 cents worth of heat. A noncooking or slow coal is necessary for this type of appliance, and because of the control of draught available, overnight banking is easily effected. In the main destructors are used for domestic water heating but there is no reason why they should not be also used for partial central heating, providing warmth to hall or bedroom. A destructor used in this way has an efficiency of approximately 60 per cent to 65 per cent. Whole-house heating from a central appliance may be either of the hot water radiator or the warm air system. Central heating by either method gives controlled temperature in every room of the house, and can be timeswitched and thermostatically controlled, so that apart from topping up the coal hopper and removing ashes, the system requires virtually no attention. The automatic firing method employed ensures that once the fire is kindled it remains lit, slumbering quietly until heat is called for by thermostat or time switch, and loss of ignition with consequent mess is avoided. The conventional low pressure hot-water system is used extensively in homes, schools and

offices, and can readily be extended at any time. It is now of the small bore, pump assisted type, using water pipes of -Jin. copper, meaning that it is not essential to have it installed during the building of the house. Smallbore central heating can be fitted at any time, the piping running unobtrusively along the skirting boards. A recent addition to the range of centralheating appliances is the warm air furnace illustrated. This circulates air from a fan at the back of the unit and can be either free standing, for use in a large room, or sited in the hall, garage, or basement with suitable air ducts supplying the various rooms. At present this is only available in one size suitable for an area of up to 1400 sq. ft. Central heating systems have an efficiency of approximately 65 percent to 70 per cent. Recently, tests were undertaken by the Coal Research Association on coal-fired domestic appliances used extensively in parts of Europe where similar coals to those in New Zealand are mined. It was found that with some minor modifications, the same appliances are extremely suitable to New Zealand needs.

All this is undoubtedly attractive. Some tend to think of coal as an antiquated method of heating domestic and industrial-wise Nothing could be further from the truth. About 52 per cent of the total heat generated in New Zealand is derived from coal. When coal is used, it should be with the assistance of modern technological know-how. In most cases, that cheerful open fire, although so good to warm our hands by, and possibly a great morale booster, is a dead loss when it comes to efficient heating. Now efficiency, when used in this context, means the heat that is actually used to warm the room as compared with the amount of heat available in the coal. This, believe it or not, works out to about 15 per cent. Perhaps quite a number of people are still mystified. However, when you explain that if a bag of coal costs $1.40 and all that is obtained from this is 21 cents worth of heat, perhaps the point becomes clearer.

The down-draught system mentioned before is used where smoke, which is always generated from coal as it is heated, is passed downward through the fuel bed and consumed. These appliances incorporate their own hoppers so that continued feeding of the fire is avoided and heat control is by thermostat. Continuous research is carried on with new appliances and methods developed for improving the old. The coal industry is fully aware of its duty to the public and fuel engineers are available in each of the main centres to give impartial advice to all coal users, whether they are householders, using a bag of coal a week, or industrial consumers using tons per week. The service is free for the asking. This may be provided for by a District Heating system. One boiler house, automatic in operation, with efficiencies exceeding 80 per cent, would supply hot water to a district through insulated mains to houses individually. metred and thermostatically controlled. Types of this system are already in use in some overseas countries where winters are longer and more severe than our own. Initial capital costs are high but running costs are low. This is self evident when the comparison is made between one highly efficient unit and the collective waste of burning hundreds of open fires. Communities, however, as well as individual householders, are forced to compromise. This is a necessity borne of resources, or lack of them, and however ideal we may consider this to be. we just cannot have it in this country—yet.

You will notice that the reference was to most open fires. Have a look at yours! Have you got the open basket grate with no means of controlling the air that passes through the fire ? Then you are doomed to burning your coal at the fastest rate possible with no method of slowing its progress. Have you a large, poorly designed, throat to your chimney? Has your fire a firebrick back shaped to give maximum radiation and to provide a suitable lead-in to the throat? Large throats allow too much air up the chimney when the fire is hot, causing draughts at one’s back and feet. They also, in the early stages of lighting the fire, help to cause that irritating puff of smoke which rolls out into the room and begrimes that new wallpaper. The importance of these three features has been emphasised by the coal industry in an effort to raise the efficiency of this type of heating that is acceptable to so many. If you have these three things, the efficiency could be raised to about 25 per cent so that now 35 cents worth of heat instead of 21 cents worth are obtained from $1.40 bag of coal. An improvement —l4 cents has been saved. Almost any coal is suitable, especially with good draught control, but usually the “fast” coals from Greymouth or Westport are more favoured. All of us have our own ideas as to what constitutes a comfortable level of heating in our various sized and