If the roof is kept tight, and the walls thoroughly painted, with good materials, at intervals not too long, a wooden house should not give much trouble by leakage, but the fireplaces and chimneys will often cause anxiety. All houses have brick chimneys, and most houses have also brick fireplaces, with brick hearths, covered with tiling or not, as the case may be. All these may show defects, and the chimney above the roof is sure to deteriorate, by the weathering of the mortar, which rapidly decays under the influence of rain and frost. If the chimney-stack rises high above the roof, the effect of the weathering will be first seen in the bending of the stack toward the quarter from which the rains come (Fig. 5); and, if this is allowed to go too far, the stack may fall. If the chimney is short and stout, it will not bend, but the upper bricks will become loose (Fig. 6), and may fall down the flues, causing a stoppage which can be remedied only with great difficulty; so that all chimneys should be watched, and the upper portion rebuilt as soon as signs of decay appear. As in the case of roofers, only thoroughly trustworthy masons should be allowed to touch a chimney, and any portions rebuilt above the roof should be laid in clear cement.

Chimneys And Fireplaces 6

Fig. 5.

Chimneys And Fireplaces 7

FIG. 6.

Inside the house, the chimneys and fireplaces may also give trouble. The old practices of building chimneys on the floor-beams, or leading them obliquely around a house, resting on pieces of joist, are now generally abandoned, and a modern chimney usually stands erect on its foundations, so that it is not likely to crack open or collapse; but the flues may be too small, or otherwise improperly built, and give annoyance in consequence. Open fireplaces require large flues, at least 8 x 12 inches for a fireplace of ordinary size, built separately to the top. If they are smaller than this, or if they are contracted at the top, as is sometimes done in pursuance of a mistaken theory, or are in any other way obstructed, the fireplaces will smoke; and if a fireplace flue is united with another flue before it reaches the top of the chimney, as is often the case in cheaply built houses, the smoke from a newly built fire will ascend one of the flues and descend the other, coming out in the room to which the latter belongs.

It is not an easy matter to remedy a defective flue. If it has been contracted at the top, this portion can be taken off and rebuilt properly; and, occasionally, a partition can be built between two flues which unite only at the top, or a partition of sheet iron can be inserted; and obstructions in the flue may be sounded for with a heavy iron ball, attached to a string, and, if the trouble is caused by loose bricks or mortar, caught in the flue, they may often be dislodged by pounding them with the ball.

Flues.

Remedying defective flues.

If the flue is hopelessly too small for an open fireplace, it can often be utilized for a stove. Even an open stove will work well with a much smaller flue than would be required for a fireplace, for the reason that the smoke and gases from a stove are hotter and more concentrated than those from a fireplace, and, in consequence, ascend more rapidly and in a smaller space. A close stove, for similar reasons, will work with a flue still smaller than that required for an open one.

Even if the flue is properly built, large enough and high enough, it may be exposed to down-draughts from neighboring hills, or buildings, or roofs, or even trees. It is a peculiarity of air in motion that it clings tenaciously to the surfaces over which it passes, following their irregularities; and a current of wind, meeting a hill, or building, or roof, or other obstruction, climbs up one side of it, and climbs down the other; and, if the top of a chimney-flue happens to be in the descending current, a down-draught will be caused whenever the wind blows from the obstruction toward it. A defective draught in a chimney, due to this cause, can be distinguished by its occurrence only when the wind blows from certain directions; and, in studying phenomena of this sort, it should be remembered that a high, steep hill is capable of producing down-draughts in chimneys a mile or more away. Downward currents of this sort from neighboring hills or mountains are not easily cured. In the city of Geneva, which lies in a plain between two ranges of steep hills, down-draughts are so prevalent that it is usual to provide each flue with two outlets, turned in different directions, so that, if the air descends on one side of the flue, it may still have a chance to escape on the other; and, in extreme cases, a flue may be divided by a long strip of sheet iron hung in it, or two flues may be appropriated to the same fireplace, each division having its own outlet, so that the downward and upward current may be kept from mixing.

Down-draughts.

In most cases, however, the down-draughts due to obstructions to windward of a chimney may be prevented by covering the top of the flue or chimney with a semi-cylindrical cap of brick or metal, having its axis at right angles with the direction from which the downward current reaches it, so that the smoke can issue from the ends of the cap (Fig. 7). The chimney should, even with this precaution, be carried up as high as possible, both to increase the natural draught, and to raise its outlet into a stratum where the downward current is less marked than it is nearer the ground. If, as occasionally happens, the flue is unnecessarily large, a similar effect can be obtained by contracting it toward the upper end, so as to give a tapering top to the chimney. The contraction of the flue concentrates the smoke, and prevents it from being mixed by diffusion with cold air as it approaches the outlet; and the tapering sides deflect upward the horizontal currents of wind which strike them, and even currents slightly descending, so that, instead of hindering the discharge of the smoke, they assist it (Fig. 8). The same form may be given to the top of a chimney without diminishing the size of the flues by cutting the bricks, and it is often advantageous to do so. A trumpet-shaped chimney-top, although picturesque and "English," is objectionable, often causing down-draughts by deflecting downward the currents which strike it.

Even if a fireplace flue is properly built, large enough, high enough, and not exposed to downward currents, the fireplace connected with it may still smoke from faulty construction. The proper form is shown in plan in Figure 9, and in section in Figure 10. The sides are usually bevelled, for the sake of radiating more heat into the room, and a portion of the back is made to slope forward for the same purpose. The back should be drawn forward to the "throat," which should be a mere slit not more than two inches wide; and just behind the throat should be a level shelf about six inches above the top of the fireplace opening. The narrowing of the throat, into which the flame and smoke are directed by the sloping back, prevents the entrance with them into the flue of cold air, which would chill the ascending gases and check the draught; and the level shelf behind the throat serves to repel occasional downward puffs of air, and send them back up the chimney, instead of deflecting them out into the room, as a sloping surface in that position would do. A fireplace damper serves in the same way to concentrate the smoke and gases, and, if properly made and placed, improves the draught.

Chimneys And Fireplaces 8

FIG. 7.

Chimneys And Fireplaces 9

FIG. 8.

Fireplaces.

Chimneys And Fireplaces 10

Fig. 9.

Chimneys And Fireplaces 11

Fig. 10.

Besides being properly formed, a fireplace should not be too large or too high. If the opening is more than thirty inches high, whatever its width, smoke is likely to be blown out into the room by the movement of persons near it; and if short pieces of wood are burned in a wide fireplace, or if a portable grate for coal is set in a fireplace which it does not fill, the draught is greatly injured by the cold air which enters the vacant spaces at the sides of the burning fuel and mixes with the smoke. Trouble from this cause may be easily remedied by building little masses of brick at the sides of the fireplace, ten or twelve inches high, leaving between them just room for the grate, or for the wood ordinarily used; and, if the fireplace opening is too high, a copper or brass plate may be fastened over it.

A good fireplace is a precious possession in a house, and deserves to be cared for. In brick fireplaces the bricks at the back, where most exposed to the fire, crack, and slowly crumble away; but they can be replaced by new ones without much difficulty. Iron linings, if too thin, are apt to warp, but, if they have been well backed up with bricks and mortar, the warping may not affect the usefulness of the fireplace. Tile linings are, as a rule, meant only for show, and are incapable of resisting fire; but the soapstone linings once popular are quite durable.

Dampers.

The care of fireplaces.

In buildings with wooden beams the hearth, through the shrinkage of the floor-timbers around it, often cracks. If the hearth has been properly built on a brick trimmer arch, there is little danger from such cracks, as a spark falling through them is stopped by the brick arch beneath; but they are unsightly, and alarming to nervous people, and it is safest to fill them with cement, colored to match the hearth. If the latter is of brick, or of red tiles, the cement may be colored with Venetian red; and tiles of other colors, or marble, may be imitated in the same way.

In general, if a fireplace smokes, a diagnosis of the trouble may be made by observing, first, whether the smoking is intermittent or constant, and, if it is constant, whether it tends to diminish. If intermittent, it is probably caused by down-draughts, which may be treated as described above. If it is constant, but tends to diminish, it may be due to the dampness of the chimney. A flue which has been long unused, and is cold and damp, chills the current through it, checking the draught very materially until the masonry has become warm and dry; so that it should not be condemned until it has been well dried out by burning newspapers in it, or by keeping up the fire for a few days. If this fails to produce improvement, and burning newspapers show that the chimney draught is good, the fault is probably in the fireplace. The chances are that this is too high. The surprising effect produced, in quickening a fire, by simply holding a wide board, or a folded newspaper, over the upper part of the fireplace opening, affords a striking lesson upon the importance of keeping such openings low; and a few experiments of this sort will soon show how much height the particular fireplace under examination will bear.