The very general cause of smoky chimneys is that the chimney top is below the level of some adjacent building, tree, or other object that obstructs the free passage of the wind. In this instance the trouble is only experienced when the wind is in certain quarters, and sometimes this can be cured by a wind-guard or cowl (no particular make can be recommended, as their efficiency differs under different circumstances); but the only reliable remedy is to raise the chimney either by pipe or brickwork to the required height. The manner in which the annoyance is brought about is, that when the wind passes over the chimney top its progress is arrested by the higher object, and it may be said to rebound (the action is rarely quite alike in any two instances), causing either a portion of the gust to pass a short way down the chimney or to momentarily stop the up draught; this will be noticed by the gusts of smoke that come from the stove into the room.
When the smoke slowly oozes into the room, it is caused by sluggish draught, or often by the construction of the grate. If the grate has considerable distance between the fire-bars and the opening into the chimney above, it permits the heavy cold air to accumulate and obstruct the heated up-flow from the fire; this generally is only noticeable when the fire is first lighted or heavily fed. It is exactly the same result as is experienced with the old-fashioned open kitchen ranges, which nearly always require a sheet of metal or “blower” across the opening to prevent their smoking. The above-mentioned grates require a strong draught to work them perfectly; or if a strong draught does not exist, a small piece of sheet-metal should be provided to fit over the open space above the front bars when necessary to establish the fire, as explained with the “Eagle” grate.
Sluggish draughts are from a variety of causes, among which might be named, insufficient height of chimney; chimneys which by any cause may become damp or cold, or lose their heat rapidly; leakages, holes or fissures, and a variety of causes too numerous to mention here. The interior surface of a chimney should be as smooth as possible, and should be swept at regular and moderately frequent intervals, otherwise the draught will be reduced.
Every fireplace should have a distinct and separate flue; sometimes two fireplaces can be successfully worked into one chimney, but provision must be made for tightly closing off either one when not in use.
Hot Water.—Heating by means of the circulation of hot water has been in vogue many years, but has not found favour for warming living-rooms and apartments, owing chiefly to the want of the air of comfort, and the warmth is not quite so agreeable as that radiated from an open fire; but this mode of heating is especially well adapted for conservatories, cold halls, public buildings, &c., as the heat-giving surface can be extended wherever desired, and so heat the place equally throughout; and upon the low-pressure system there is no danger, as the water cannot heat higher than boiling-point, 212° F., an advantage that the hot-air system does not possess. The principle and cause of hot-water circulation will be found fully described under hot-water apparatus; but in this arrangement there are no draw-off taps, the services being for circulating only. For small purposes the apparatus can be attached to the ordinary bath boiler of the kitchen range; but there is a serious disadvantage in this when the heat is for conservatories or where warmth is particularly required at night, as that is the time when the kitchen fire is not in use. For larger purposes, independent boilers are used, varying in size according to the requirements. Portable boilers with fire-box, &c., complete, can be obtained almost anywhere, and most slow-combustion stoves (the “Tortoise,” for instance) can be fitted with boilers for this purpose. It will be understood that these boilers do not require cleaning out like kitchen-range boilers, as there is no appreciable deposit, the same water being heated day after day and only losing say a quart per month by evaporation.
The arrangement for a hall with an independent boiler is to have several horizontal pipes suitably fixed one above the other and known as a “coil,” from which the heat is radiated, and this coil is connected by a “flow” and “return” pipe with the boiler: a small cistern of about 2 gallons capacity is connected with, and fixed a little above the level of the highest part of the coil in some convenient place. The apparatus is charged through this cistern, and a small quantity of water is added thereto periodically to make good loss by evaporation and to keep the coil full; these coils are usually covered with an iron grated casing, with a metal, slate, or marble top, which is both a useful and ornamental adjunct to the hall.
For conservatories the coil is not used, the radiating pipes being run along the wall near the ground; a portion of the pipe has a shallow open trough cast upon it, and this is filled with water. As the apparatus becomes heated, evaporation takes place, and this saturates the air, moisture being essential for this purpose.
For public buildings, &c., coils are sometimes used; but more often the pipes are run in grated-topped channels just beneath the floor, the grating being level with the floor-boards; they are taken around or across the building, as is most desirable to obtain an equable heat.
The radiating pipes, whether single or forming coils, are generally 4 in. diameter, of cast iron (cast iron being a better conductor or dissipator than wrought), and at the highest point m the apparatus a hole is drilled and a small cock is inserted; this cock is opened when charging, to allow of the free escape of the air in the pipes, and it is sometimes of service to discharge any steam that is generated. The pipes are made with a socket at one end, into which the plain end of the next pipe is inserted and packed with yarn, &c.; but a modern and rapid method of joining the pipes is that patented and manufactured by Jones and Attwood, of Stourbridge; this joint consists of two flanges with indiarubber packing between, which makes a perfectly secure joint by tightening the flanges together; in this method the ends of the pipes are of equal size.