Chapter 14

=Warming=

=Ventilation and Heating.=--The subject of the heating of our rooms and houses is very closely allied to that of ventilation, not only because both are a special necessity at the same time of the year, but also because we cannot heat a room without at the same time having to ventilate it by providing an egress for the products of combustion and introducing fresh air to replace the vitiated.

=Need of Heating.=--In a large part of the country, and during the greater period of the year, some mode of artificial heating of rooms is absolutely necessary for our comfort and health. The temperature of the body is 98 deg. to 99 deg. F., and there is a constant radiation of heat due to the cooling of the body surface. If the external temperature is very much below that of the body, and if the low temperature is prolonged, the radiation of heat from the body is too rapid, and colds, pneumonia, etc., result. The temperature essential for the individual varies according to age, constitution, health, environment, occupation, etc. A child, a sick person, or one at rest requires a relatively higher temperature than a healthy adult at work. The mean temperature of a room most conducive to the health of the average person is from 65 deg. to 75 deg. F.

=The Three Methods of Heating.=--The heating of a room can be accomplished either _directly_ by the rays of the sun or processes of combustion. We thus receive _radiant_ heat, exemplified by that of open fires and grates.

Or, the heating of places can be accomplished by the heat of combustion being conducted through certain materials, like brick walls, tile, stone, and also iron; this is _conductive_ heat, as afforded by stoves, etc.

Or, the heat is _conveyed_ by means of air, water, or steam from one place to another, as in the hot-water, hot-air, and steam systems of heating; this we call _convected_ heat.

There is no strict line of demarcation differentiating the three methods of heating, as it is possible that a radiant heat may at the same time be conductive as well as convective--as is the case in the Galton fireplace, etc.

=Materials of Combustion.=--The materials of combustion are air, wood, coal, oil, and gas. Air is indispensable, for, without oxygen, there can be no combustion. Wood is used in many places, but is too bulky and expensive. Oil is rarely used as a material of combustion, its principal use being for illumination. Coal is the best and cheapest material for combustion. The chief objection against its use is the production of smoke, soot, and of various gases, as CO, CO2, etc. Gas is a very good, in fact, the best material for heating, especially if, when used, it is connected with chimneys; otherwise, it is objectionable, as it burns up too much air, vitiates the atmosphere, and the products of combustion are deleterious; it is also quite expensive. The ideal means of heating is electricity.

=Chimneys.=--All materials used for combustion yield products more or less injurious to health. Every system of artificially heating houses must therefore have not only means of introducing fresh air to aid in the burning up of the materials, but also an outlet for the vitiated, warmed air, partly charged with the products of combustion. These outlets are provided by chimneys. Chimneys are hollow tubes or shafts built of brick and lined with earthen pipes or other material inside. These tubes begin at the lowest fireplace or connection, and are carried up several feet above the roof. The thickness of a chimney is from four to nine inches; the shape square, rectangular, or, preferably, circular. The diameter of the chimney depends upon the size of the house, the number of fire connections, etc. It should be neither too small nor too large. Square chimneys should be twelve to sixteen inches square; circular ones from six to eight inches in diameter for each fire connection. The chimney consists of a _shaft_, or vertical tube, and _cowls_ placed over chimneys on the roof to prevent down draughts and the falling in of foreign bodies. That part of the chimney opening into the fireplace is called the _throat_.

=Smoky Chimneys.=--A very frequent cause of complaint in a great many houses is the so-called "smoky chimney"; this is the case when smoke and coal gas escape from the chimney and enter the living rooms. The principal causes of this nuisance are:

(1) A too wide or too narrow diameter of the shafts. A shaft which is too narrow does not let all the smoke escape; one which is too wide lets the smoke go up only in a part of its diameter, and when the smoke meets a countercurrent of cold air it is liable to be forced back into the rooms.

(2) The throat of the chimney may be too wide, and will hold cold air, preventing the warming of the air in the chimneys and the consequent up draught.

(3) The cowls may be too low or too tight, preventing the escape of the smoke.

(4) The brickwork of the chimney may be loose, badly constructed, or broken into by nails, etc., thus allowing smoke to escape therefrom.

(5) The supply of air may be deficient, as when all doors and windows are tightly closed.

(6) The chimney may be obstructed by soot or some foreign material.

(7) The wind above the house may be so strong that its pressure will cause the smoke from the chimney to be forced back.

(8) If two chimneys rise together from the same house, and one is shorter than the other, the draught of the longer chimney may cause an inversion of the current of air in the lower chimney.

(9) Wet fuel when used will cause smoke by its incomplete combustion.

(10) A chimney without a fire may suck down the smoke from a neighboring chimney; or, if two fireplaces in different rooms are connected with the same chimney, the smoke from one room may be drawn into the other.

=Methods of Heating.= =Open Fireplaces and Grates.=--Open fireplaces and fires in grates connected with chimneys, and using coal, wood, or gas, are very comfortable; nevertheless there are weighty objections to them. Firstly, but a very small part of the heat of the material burning is utilized, only about twelve per cent being radiated into the room, the rest going up the chimney. Secondly, the heat of grates and fireplaces is only local, being near the fires and warming only that part of the person exposed to it, leaving the other parts of the room and person cold. Thirdly, the burning of open fires necessitates a great supply of air, and causes powerful draughts.

The open fireplace can, however, be greatly improved by surrounding its back and sides by an air space, in which air can be warmed and conveyed into the upper part of the room; and if a special air inlet is provided for supplying the fire with fresh air to be warmed, we get a very valuable means of heating. These principles are embodied in the Franklin and Galton grates. A great many other grates have been suggested, and put on the market, but the principal objection to them is their complexity and expense, making their use a luxury not attainable by the masses.

=Stoves.=--Stoves are closed receptacles in which fuel is burned, and the heat produced is radiated toward the persons, etc., near them, and also conducted, through the iron or other materials of which the stoves are made, to surrounding objects. In stoves seventy-five per cent of the fuel burned is utilized. They are made of brick, tile, and cast or wrought iron.

Brick stoves, and stoves made of tile, are extensively used in some European countries, as Russia, Germany, Sweden, etc.; they are made of slow-conducting material, and give a very equable, efficient, and cheap heat, although their ventilating power is very small.

Iron is used very extensively because it is a very good conductor of heat, and can be made into very convenient forms. Iron stoves, however, often become superheated, dry up, and sometimes burn the air around them, and produce certain deleterious gases during combustion. When the fire is confined in a clay fire box, and the stove is not overheated, a good supply of fresh air being provided and a vessel of water placed on the stove to reduce the dryness of the air, iron stoves are quite efficient.

=Hot-air Warming.=--In small houses the warming of the various rooms and halls can be accomplished by placing the stove or furnace in the cellar, heating a large quantity of air and conveying it through proper tubes to the rooms and places to be warmed. The points to be observed in a proper and efficient hot-air heating system are the following:

(1) The furnace must be of a proper size in proportion to the area of space to be warmed. (2) The joints and parts of the furnace must be gas-tight. (3) The furnace should be placed on the cold side of the house, and provision made to prevent cellar air from being drawn up into the cold-air box of the furnace. (4) The air for the supply of the furnace must be gotten from outside, and the source must be pure, above the ground level, and free from contamination of any kind.[16] (5) The cold-air box and ducts must be clean, protected against the entrance of vermin, etc., and easily cleaned. (6) The air should not be overheated. (7) The hot-air flues or tubes must be short, direct, circular, and covered with asbestos or some other non-conducting material.

=Hot-water System.=--The principles of hot-water heating are very simple. Given a circuit of pipes filled with water, on heating the lower part of the circuit the water, becoming warmer, will rise, circulate, and heat the pipes in which it is contained, thus warming the air in contact with the pipes. The lower part of the circuit of pipe begins in the furnace or heater, and the other parts of the circuit are conducted through the various rooms and halls throughout the house to the uppermost story. The pipes need not be straight all through; hence, to secure a larger area for heating, they are convoluted within the furnace, and also in the rooms, where the convoluted pipes are called _radiators_. The water may be warmed by the low- or high-pressure system; in the latter, pipes of small diameter may be employed; while in the former, pipes of a large diameter will be required. The character, etc., of the boilers, furnace, pipes, etc., cannot be gone into here.

=Steam-heating System.=--The principle of steam heating does not differ from that of the hot-water system. Here the pressure is greater and steam is employed instead of water. The steam gives a greater degree of heat, but the pipes must be stronger and able to withstand the pressure. There are also combinations of steam and hot-water heating. For large houses either steam or hot-water heating is the best means of warming, and, if properly constructed and cared for, quite healthy.[17]

FOOTNOTES:

[16] Great care should be taken that the air box is not placed in contaminated soil or where it may become filled with stagnant or polluted water.--EDITOR.

[17] See Chapter XI for practical notes on cost of installation of these three conveyed systems--hot-air, hot-water, and steam.--EDITOR.