The value or efficiency of the heating surface varies so widely in different makes that it is best to state the required conditions to the manufacturers and have them proportion the surfaces as their experi ence has found best for their particular type of furnace.
Care and Management of Furnaces. The following general rules apply to the management of all hard coal furnaces.
The fire should be thoroughly shaken once or twice daily in cold weather. It is well to keep the firepot heaping full at all times. In this way a more even temperature may be maintained, less attention is required, and no more coal is burned than when the pot is only partly filled. In mild weather the mistake is frequently made of carrying a thin fire, which requires frequent attention and is likely to die out. Instead, to diminish the temperature in the house, keep the firepot full and allow ashes to accumulate on the grate (not under it) by shak ing less frequently or less vigorously. The ashes will hold the heat and render it an easy matter to maintain and control the fire. When feeding coal on a low fire, open the drafts and neither rake nor shake the fire till the fresh coal becomes ignited. The air supply to the fire is of the greatest importance. An insufficient amount results in incom plete combustion and a great loss of heat. To secure proper combus tion, the fire should be controlled principally by means of the ash-pit through the ash-pit door or slide.
The smoke-pipe damper should be opened only enough to carry off the gas or smoke and to give the necessary draft. The openings
in the feed door act as a check on the fire, and should be kept closed during cold weather, except just after firing, when with a good draft they may be partly opened to inc rease the air-supply and promote the proper combustion of the gases.
Keep the ash-pit clear to avoid warping or melting the grate. The cold-air box should be kt pt wide open except during winds or when the fire is low. At such times it may be partly, but never com pletely closed. Too much stress cannot be laid on the importance of a sufficient air-supply to the furnace. It costs little if any more to maintain a comfortable temperature in the house night and day than to allow the rooms to become so cold during the night that the fire must be forced in the morning to warm them up to a comfortable temperature.
In case the warm air fails at times to reach certain rooms, it may be forced into them by temporarily closing the registers in other rooms. The current once established will generally continue after the other registers have been opened.
It is best to burn as hard coal as the draft will warrant. Egg size is better than larger coal, since for a given weight small lumps expose more surface and ignite more quickly than larger ones. The furnace and smoke-pipe should be thoroughly cleaned once a year.
This should be done just after the fire has been allowed to go put in the spring.