United States Stove Company 1821 Owner's Manual page 8

Many people may wish to convert an existing fireplace to
heater use. Usually, safe connection of stovepipe to a
masonry chimney requires more effort than connection to a
prefabricated chimney. The fireplace must be tightly closed
and sealed at the damper in the flue. Good sealants are high-
temperature caulking, ceramic wool, and furnace cement.
Always remember to inspect the masonry chimney and
fireplace. If necessary, clean the flue and smoke shelf
before beginning your installation. Install the heater into the
fireplace so that the system can be dismantled for cleaning
and inspection.
Before deciding to convert your fireplace, keep in mind that
some fireplaces and existing chimneys are unsafe. They
must be structurally sound, and the flue liner must be in good
condition. Do not use a chimney if it is unlined (should have
a fire clay tile liner to protect brickwork). Have it relined
professionally. Clearances to combustibles are explained in
the previous section on masonry chimneys. If you have any
questions regarding the condition of the chimney, consult a
qualified engineer, competent mason, or knowledgeable
inspector.
Many prefabricated fireplaces fall into the "zero-clearance
fireplace" category. This is a factory-built metal fireplace
with multilayered construction. It is designed to provide
enough insulation and/or air cooling so that the base, back
and sides can be safely placed in direct contact with
combustible floors and walls. Although many prefabricated
fireplaces have been tested by nationally recognized organi-
zations for use as fireplaces, they have not been tested to
accept heaters. In fact, their use as such may void the
manufacturer's warranty.
Steel-lined fireplaces, on the other hand, can be used with
heaters. These units use a 1/4-inch firebox liner and an air
chamber in connection with 8 inches of masonry to meet
code. They contain all the essential parts of a fireplace,
firebox, damper, throat, smoke shelf, and smoke chamber.
Many of them look exactly like a masonry fireplace and must
be checked closely for above requirements before installing
a wood heater into them.
Another method frequently used by some people is to vent
the heater directly into the fireplace. This does not meet
code since the heater is being vented into another appliance
- the fireplace. This method should not be attempted
because combustion products will deposit and build up in the
firebox or fireplace. Be certain not to install a hazard in your
house. You will void your warranty with this installation.
VENTING INTO A FIREPLACE
When considering a masonry chimney, round tiles are
preferable to square or rectangular, as round tiles have much
better airflow characteristics and are far easier to clean.
Unfortunately, most North American chimneys use square
or rectangular tile liners that are really designed for open
fireplaces, not stoves or furnaces. Of most importance,
second only to overall chimney height, is the diameter of the
flue liner itself. In most instances, it should be sized to the
appliance; i.e., 6" flue outlet on the appliance requires a 6"
chimney. The inner diameter should never be less than the
flue-outlet diameter and should never be greater than 50%
larger than the appliance flue outlet. For example, do not
expect a wood or coal burning stove or furnace to function
properly if installed into a chimney with a flue greater than
50% more than the appliance outlet - - such as a 6" flue outlet
requires a 6" diameter for optimum drafting, but can function
well with an 8", but becomes borderline beyond an 8"
diameter.
Masonry chimneys built of concrete blocks with or without
flue liners do not meet modern building codes. A solid fuel
appliance must not be joined to a chimney flue which is
connected to another appliance burning other fuels.
If your chimney has a typically oversized flue liner of, say 8
x 12 inches, or greater, or if it is unlined, it will be necessary
for you to reline the chimney, using any of the modern
approved and economical methods such as stainless steel,
castable refractory, or properly sized fireclay linings.
If you have any questions regarding venting your appliance,
feel free to contact the factory at the address and phone
number on this Owner's Manual. You may also contact
NFPA (National Fire Protection Association) and request
NFPA Standard 211 (1984 Edition). Their address is Battery
March Park, Quincy, Massachusetts 02269. Another help-
ful publication is NFPA Standard 908, available at the same
address. Specify 1984 Edition of either of the above
publications.
CAUTION:
NOT ALL FIREPLACES ARE
SUITABLE FOR INSTALLATION
OF A WOOD HEATER.
8