The health and comfort of the home depends to a considerable extent upon the heating apparatus, which, in importance, is second only to that of sanitary plumbing.  Stoves are a development of the fireplaces of our ancestors.  Their waste of fuel, their uncleanliness, and their inability to properly heat even one room are features recognized by most people.  The ideal heating apparatus is one that will promptly and continuously supply every room in the house with enough warm fresh air to make it comfortable in the coldest weather.  It must be easy to manage and not complicated in construction.  The cost of installing a steam or hot-water system is more than that of a hot-air furnace.  The amount of fuel used by them is less, but for a small house the hot-air furnace is most often used.  It has the advantage, too, if properly installed, of supplying fresh air, while the other systems demand special means for ventilation, or dependence must be placed entirely upon opening the doors and windows.


A furnace is a stove within a casing of galvanized iron or brick.  Air is admitted to the space between the two and when it becomes heated passes through pipes to the different rooms of the house. The furnace may be constructed of cast iron, wrought iron, or steel.  The cast-iron furnace has fewer joints than the one made of steel plates and will not vary in temperature so rapidly.

Direct and indirect draft. - In construction there are two styles, the "direct" and the "indirect" draft.  The better class of the "direct" draft furnaces have a radiator through which the hot gases pass on their way to the smokestack, and so utilize much heat that would otherwise be lost.  In the "indirect" draft furnaces the gases pass through radiators at the bottom and from there to the smokestack.  A direct passage is furnished to be used when the fire is being started or when coal is being added.  Some furnaces are "built to sell" by their size and are not furnished with a radiator.  These will burn more fuel and give off less heat.

The smoke pipe. - The smoke pipe should connect to the chimney as directly as possible, for elbows diminish the draft.  The flue should be at least 8 inches by 12 inches and should have no other opening into it for range or fireplace.  A clean-out door should be provided at the bottom, fitted with a tight door, and this door must be kept shut, except when cleaning out the flue.

The grate. - The grate is one of the most important parts of a furnace, and there are many kinds to be had.  The essential things are the removal of th ashes and cinders from the entire grate surface without carrying unburned coal with them, and the admission of air to secure proper combustion of the fuel.  In comparing furnaces the average diameter of the fire pot is taken.  The space above must be large enough to permit of the thorough mixing of the gases with air or else much heat will be lost by imperfect combustion.  If soft coal is to be burned a larger combustion chamber is needed than with hard coal, as the supply of air must be greater.

Furnaces differ in the manner of bringing the air to be warmed into contact with the surfaces heated by the combustion of the fuel.  The area of the heating surfaces should be about 60 times the area of the grate surface to prevent overheating of the air in cold weather.

Where natural gas is available the furnace can be arranged to burn it, but it is well to have a coal grate also in case the gas should be shut off.  Wood furnaces are generally more simple in construction and are often built to take a 4-foot stick.  Where wood is cheap excellent results may be obtained.  The smoke should pass through a radiator, as in case of coal furnaces.

Distribution of hot air by means of pipes. - Much depends upon the location of the furnace.  It should be placed somewhat to the north and west of the center of the house - that is, toward the prevailing cold winds.  As the hot air travels best through the pipes leading toward the sheltered part of the house and to the upper rooms, the pipes leading toward the north and west or to the rooms on the first floor should be given the preference with respect to length and size.  Make all pipes as nearly the same length as possible and as short as the location of the registers will permit.  Long horizontal runs of pipe should be avoided, especially in first-floor pipes.  The pipes should pitch upward as sharply as possible so the resistance will be less.  Each pipe should have a damper near the furnace.  Each room should have a separate pipe, if possible, or the heat will go to the less-exposed room when a wind is blowing.  Exposed pipes should be provided with an asbestos covering, even when made double; double pipes are the best for all work.  Bright tin is almost always used for hot-air pipes, as it radiates less heat than any other suitable material.  The registers should be as near the furnace as possible.  Nothing is gained by putting them on the exposed side of the room and much heat is lost.  First-floor registers may be placed in the floor if wall registers would interfere with the pipes to the second floor.  Second-floor registers should be placed in the wall so as to avoid the necessity of cutting carpets and not to furnish receptacles for dirt.  If only the first floor is heated the registers should be placed in the wall.  The net area of the register should be about 15 per cent greater than the section of its hot-air pipe.

Size of pipe to use. - The size of the room and whether it is a bedroom or living room; the run of pipes, whether short or long, straight or crooked, vertical r horizontal, should all be considered in determining the size of the hot-air pipes.  Pipes can be too large, but more often they are too small.  When in doubt, use the larger size. For first-floor rooms up to 12 feet square and 10-foot ceiling, 9-inch pipes should serve; for larger rooms up to 14 feet by 16 feet with 10-foot ceilings,use 10-inch pipes; and for rooms still larger, 12-inch pipes.  Sleeping rooms and bathrooms on the first floor need 8-inch pipes.  If any pipe is poorly located a size larger should be used.

The cold-air supply. - The cold-air supply pipe should be made of galvanized iron, as it will then be dust and fire proof and more durable than if made of wood, which cracks and admits the dust and the close air of the cellar.  If it is made of wood, matched boards should be used and the wood should be stopped at least a foot from the furnace.  The size of the cold-air pipe is often made equal to three-fourths the combined area of the hot-air pipes, as air expands when heated.  It should never be smaller than this and might be made of the full area of the hot-air pipes.  If not enough cold air is supplied, the pipes leading to the sheltered side of the house will take all the air and even draw down air from registers on the windward side.  In attempting to warm these unfavorably located rooms in extreme weather the air must be overheated, which is hard on the furnace.  In localities where zero weather is frequent, a pipe is often provided to return the air of the house through the furnace.  The area of this pipe should be equal to the combined areas of the hot-air pipes.  This pipe is not to take the place of th fresh-air inlet, but can be used part of the day without harm.  If used at all, it must be used intelligently, or else the saving of fuel is at the expense of health and comfort.  When a return-air pipe is used, it often joins the fresh-air inlet pipe.  If this combination is installed, the pipe is full size from the furnace to where the inside supply pipe is connected and three-fourths size from there to the outside air.  Both pipes should be provided with dampers.  It is often necessary to shut off part of the cold-air supply to start the fire, but the full supply should be turned on as soon as possible of air will be taken from the cellar or from some of the registers.  If it is found that some registers do not deliver enough warm air while others supply too much, the dampers can be adjusted to cut off part of the flow from rooms that have more than their share, which will throw it into the less favored pipes.

Regulating the dampers. - An arrangement for regulating the dampers by hand can be placed in any convenient room on the first floor, which will reduce the labor of caring for the furnace by half, or an automatic temperature regulator can be used,which will not only secure an even temperature with less fuel but will avoid the strain on the furnace caused by forgetting to close the dampers after the fire is started until reminded of it by the excessive heat of the room.  An alarm clock with a ratchet or gear arranged to trip a lever and allow the weighted damper to open is often used to turn on the drafts in the early morning.

If the house has a fireplace or two, it is not necessary to use the furnace so early in the autumn or so late in the spring, as a small grate fire in the mornings removes the chill from the rooms with less expenditure of fuel.  A good fireplace isa precious possession.


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