THE CHIMNEY.

Progress, Volume I, Issue 7, 1 May 1906, Page 168

THE CHIMNEY.

One of the commonest things in the world is the chimney ; yet, if you should send out to a thousand builders for a definition of the word " chimney " you would not get an answer from one per cent, of those who might reply, that would convince a master workman's conception of the structure. A large percentage — perhaps fifty per cent. — taking the general range of dwelling-house chimneys, and other chimneys, are essentially defective, because they violate the requirements of the following definition : A chimney is a perfect tube, perpendicular in structure, so built as to admit smoke, gases, and air at the bottom of the tube only, and permit their escape at the top of the tube and nowhere else. The following are some of the violations of the requirements of this rule, where the chimney is built of brick, i. The bricks are porous, and are laid so poorly that sufficient air enters the chimney through the brick and mortar joists to destroy the draught. 2. The brick may be good, but laid without being thoroughly bedded in the mortar, and air enough may in this way be admitted through the sides of the chimney to destroy or weaken the draught. 3. The mortar may be poor, and its strength easily destroyed by the sulphur and other injurious fumes and gases of combustion. In my experience, I find that about twenty per cent', of chimneys permit sulphurous and other gases to pass through them into the rooms. The rotten-egg smell, so often found in closets, bedrooms, etc., is due to this.

This is mostly due to porous bricks, which seem to invite these gases to hide in their recesses and creep out into the rooms, most of which evil has been discharged to the discredit of the furnace. 4. A chimney may be placed on an outside wall, with one 4m. course between the draught and the weather. Such a chimney, even if ordinarily well constructed, may have its draught greatly impaired by air forced through the wall by wind pressure, which has a decided effect at times. 5. The value of a proportion of cement m the mortar is not as generally understood as it should be. 6 Chimneys for dwellings often cause great vexation by being too small, or by becoming a luel thief when too large. Furnace chimneys should never be less than 12m. by 12m. inside, with a damper of solid construction and simple control for reducing the capacity.