IREPLACES

It is well enough to say just how a fireplace should be built so that it
will work satisfactorily, but that does not go far in helping the man
who has a fireplace that will not work. Frequently it is possible
without any very great expense and trouble to correct a fireplace that
has been improperly built. If one has in mind a clear comprehension of
the few elementary principles of fireplace construction it will usually
be an easy matter to determine the reason why a fireplace smokes or
fails to draw.

The cross-section area of the flue is likely to prove the most common
difficulty. Usually this cannot be seen from inside the fireplace,
because of the narrow throat and the smoke chamber which in some form
may be above the shelf. If, therefore, the apparent essentials--such as
shape of opening, narrow throat across the whole width, and preferably
the slanting back--have been followed out it would be well to determine
the area of the flue itself. To do this it will be necessary to reach
the top of the chimney and, by lowering a weight on a line, find which
flue leads to the fireplace in question. Its area at the top will in all
probability be its area throughout. If the flue happens to be the only
one in that particular chimney it may sometimes be determined more
easily by counting the bricks in its two horizontal directions and in
this way estimating what would probably be the inside flue. This
conclusion is by no means sure, however, since the chimney may be built
with eight-inch walls or it may be simply a four-inch wall with the
flue lining. To one with a knowledge of bricklaying, however, the way in
which the chimney is laid up will usually indicate the size of the flue.

Having determined the size of the fireplace opening and the
cross-section area of the flue itself, it will in many cases be found
that the latter is too small for the former. The easiest way to remedy
this difficulty naturally would be to decrease the size of the opening
in the face of the fireplace. In order to check up the diagnosis,
however, it would be well to fit a pair of thin boards to wedge fairly
tightly into the opening at the top, one of which boards could be drawn
down past the other one so that the fireplace opening may be decreased
anywhere from six to twelve inches in height--using two six-inch boards.
By testing the fireplace in action in this way it will be readily
determined by what amount the opening must be decrease