CHIMNEYS AND FLUES Chimneys have a twofold object— to remove the smoke and gases pro duced by combustion, and to produce a draught to increase the rate of com bustion. They were first introduced in Europe about the twelfth century. The first chimney in Rome was built in 1368. Chimneys did not come into general use in Europe until the seven teenth century. Formerly—and to this day in many parts of the world—fires were built on stone or earthen hearths in the center of the room, the prod ucts of combustion being allowed to escape through a hole in the middle of the roof.
The draught produced by a chimney depends upon its height and propor tions. The higher the chimney, the better the draught. The flue should be about one fifth or one sixth the area of the grate.
Chimneys are the best of ventila tors, hence there should be one or more extending from the bottom of the cellar and opening by means of suitable flues and fireplaces into every living room in the house.
To Prevent Dampness in Chimneys. —Let the chimney start from the bot tom of the cellar, or, if built at the side of the house, from the foundation wall, and rest on a flat stone laid in water cement. This will prevent the bricks from absorbing moisture. A chimney resting on a foundation in the upper part of the house may ac cumulate water during a rain storm, which will . saturate the bricks and communicate dampness to adjacent walls.
Chimneys—To Prevent Soot.—Mix salt freely with the mortar in which the bricks on the inside of a chimney are laid. This will cause them to at tract moisture in damp weather, which will loosen the soot and cause it to fall. It will also prevent the chimney from becoming infested with chimney swallows.
To Ventilate Chimneys.—An open fireplace communicating with the chim ney is an ideal ventilator; or a chim ney may be built double, having two columns side by side or one within the other, one being reserved for ven tilation and communicating with each room through an opening in the ceiling.
Or a double chimney may have one column within the other, the air space between the two being connected with the rooms by ventilators.
Chimneys — To Prevent Smoke. Build a long, narrow flue 4 or 5 inches deep and 15 to 18 inches wide, thus having an opening of 60 to 90 square inches. Let the flue open into an air chamber in the chimney of twice its size, I. e., an area of 120 to 180 square inches or 11 to 16 inches squaite, but this may be reduced toward the top of the chimney if desired. Carry the chimney as high above the roof as good taste will permit, and let the flue approach the chimney at an angle, or, if possible, by a number of turns. Usually the more crooked the flue the better the draught. A straight fun nel does not usually draw well.
To Cure a Smoky Chimney.—First note the cause. Either too much air is admitted below, or the draught is insufficient, or the wind blows down into the chimney from above. Hence, according to circumstances, contract the draught by narrowing the entrance to the grate or fireplace, or increase the height or crookedness of the flue and shaft, or place on the top of the chimney a wind shield or turn cap, which will revolve with the wind in such a way as to prevent the gusts from blowing down the chimney.
The draught is caused by the fact that hot air rises and tends to create a vacuum, which by suction draws cold air after it. Hence, anything that chills the column of air in the chimney tends to check the draught. Therefore avoid admitting, across the top of the fire in a grate or fireplace, enough cold air to cool the flue. The fire should be located in such relation to the flue that the rising current of hot air will have the right of way and tend to fill the flue, to the exclusion of the cold air of the room; thus the latter will be sucked up through the fire itself, assisting the combustion and strengthening the draught.
To Kindle Fires without Smoke.— To start a draught without smoke, on kindling a fire in an open grate when the air in the chimney is cold and the first flame is feeble, use a sufficient quantity of very combustible sub stances, as kindlings, to create flames. These will heat the air in the chimney before cold or solid fuel is added, which burns less perfectly.
Or reduce the opening to the grate or fireplace by means of a blower or light screen lined with asbestos and placed across the opening so as to admit air only in the required quan tity and beneath the grate.
To Prevent Smoke.—A hot fire will consume its own smoke. Hence, to prevent the formation of smoke, heat a hot bed of coals and add fresh fuel in such limited quantity as not to lower the heat of the fire below the smoke-consuming point. Push the coals back and put on fresh fuel so that the smoke will pass over the bed of live coals, where it will be con sumed.
Or adjust a wire screen having forty or more wires to the inch, to prevent the escape •of smoke.
To Clean Chimneys.—Prepare a bed of hot coals in the stove, throw open the draughts and dampers, and throw on the coals some pieces of old zinc, as the zinc from an old washboard. This will clean out all soot from the chimney.
Or the chimney may be swept if the shaft is straight by attaching a heavy stone or other weight to the butt of a small pine or hemlock sapling and fastening a rope to its upper part. The weight will carry the sapling down the chimney, and when it is dragged back the extending branches will sweep clean the soot. Care must be taken to use a rope sufficiently strong and a sapling not too large, so as to prevent the rope from parting or the brush from lodging in the shaft.
To Stop Leaks in Chimneys.—Make a cement of coal tar and sand, and apply as may be convenient within or without.
To Put Out Fires in Chimneys.— Throw sulphur on the fire so that the fumes will ascend the flue. Take pre cautions not to breathe the fumes of burning sulphur.
Or ascend to the roof and throw salt down the chimney. Or shut off the draught from below if possible by covering the opening to the fireplace with wet blankets or otherwise. Or, if the fire is not too strong, put a tight cover over the top of the chimney.