=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.
[Illustration: FIG. 13.
A GALTON GRATE. (TRACY.)]
=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.
[Illustration: FIG. 14.
A HOT-AIR FURNACE.
The cold air from outside comes to the COLD-AIR INTAKE through the
cold-air duct, enters the furnace from beneath, and is heated by
passing around the FIRE POT and the annular combustion chamber above.
It then goes through pipes to the various registers throughout the
house. The coal is burnt in the fire pot, the gases are consumed in
the combustion chamber above, while the heat eventually passes into
the SMOKE FLUE. The WATER PAN supplies moisture to the air.]
=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.