GAS FIRED VENTED FLOOR FURNACES
9
FURNACE
CASING
DRAFT
HOOD
GASKET
MATERIAL
GASKET
MATERIAL
FIGURE 6
existing vent that has worked for years may not be
adequate for todays design because of higher efficiency
requirements that result in lower stack temperatures.
WARNING:
IMPROPER OR UNSAFE VENTING
PRESENTS A HAZARD THAT MAY RESULT IN
PROPERTY DAMAGE, BODILY INJURY OR LOSS OF
LIFE. LISTED BELOW ARE SOME GUIDELINES TO
OBSERVE WHEN INSTALLING THE VENT SYSTEM.
1. Never reduce the vent pipe to a size smaller than
the outlet on the draft hood.
2. Never run pipe more than 15 feet horizontally.
3. The total horizontal run of a vent plus the
horizontal vent connector shall be not greater
than 75% of the vertical height of the vent.
4. Slope horizontal pipe upwards at least 1/4 inch
per lineal foot.
5. Do not use more than one elbow. An elbow
restricts the flow of vent gases by approximately
10%.
6. Use a noncombustible thimble when connecting
vent pipe to a masonry chimney.
7. Do not insert vent pipe farther than 1/4 inch into
the interior of the chimney.
8. Single wall pipe must not be used.
9. Never connect the vent pipe to any chimney or
vent system serving a solid fuel-burning appliance.
10. If another appliance is being vented through
the vent system with the floor furnace, the vent
pipe must be increased to compensate for the
additional load.
11. Never install any kind of damper in the vent
system.
12. Do not use transite or any other type of ceramic
pipe for venting.
Class “B” double wall pipe is acceptable to most codes,
and if installed in accordance with the pipe manufacturers
instructions provides the safest and most efficient vent
system. Class “B” pipe has an integral lock for securing
sections together. These locks must be properly fitted
together. Fasten pipe to draft hood using at least three
self-tapping sheet metal screws at equal intervals around
the circumference of the pipe. Support horizontal pipe at
three-foot intervals with metal strapping attached to joists.
The floor furnace you have selected was carefully designed
to operate both safely and efficiently when vented with the
proper size vent listed for each furnace on
page 5
.
We do not recommend doing so, but if you must vent
into a masonry chimney, use the following instructions.
If the floor furnace is vented into a masonry chimney, the
chimney must be inspected to determine that it is clear
and free of obstructions and that it is safe for the intended
use. The inside of the chimney must be at least 6 inches
in diameter or 6 inches by 6 inches if rectangular. Insert
the vent pipe into the chimney through a masonry or
noncombustible corrosion-resistant thimble of the correct
diameter. Do not push the pipe farther than 1/4 inch into
the inside of the chimney.
Figure 7A
Pushing the pipe
farther into the inside of the chimney may cause partial or
complete blockage as illustrated in
Figure 7B
.
Even following these instructions you may still have a
venting problem because of the larger area to be heated
inside the chimney. This could cause pilot outage, odors
coming from the furnace, or noise due to excessive heat
not being vented out of the combustion chamber. If
you experience any of these problems, we recommend
running the proper size “B” type vent pipe down the
chimney and connecting to the horizontal run of vent pipe
with a 90-degree elbow inside the chimney.
Figure 7C
Extend the vent system at least 3 feet above the point
where it exits the roof and at least two feet higher than
any part of the roof system within 10 feet. Terminate with a
listed or approved cap.
Figure 8
1/4"
FIGURE 7A - SAFE
FIGURE 7B - UNSAFE
