Specifications

18
Observe the following precautions when venting the unit:
1. Use fl ue pipe of the same size as the fl ue connections on
the gas unit heater (See Table #1). All heaters should be
vented with double wall or single wall vent, a factory built
chimney, or a lined brick and mortar chimney that has
been constructed in accordance with the National Building
Code. Type B vent should only be used for vertical rise
portions of a Category I vent pipe system. Type B vent
pipe should not be used for horizontal runs of vent pipe.
2. Provide as long a vertical run of fl ue pipe at the gas
unit heater as possible. A minimum of 5' (1.5m) of
vertical flue is required. The top of the vent pipe
should extend at least 2' (0.61m) above the highest
point on the roof. Install a weather cap over the
vent opening. Consideration should be made for
anticipated snow depth.
3. Slope horizontal runs upward from the gas unit
heater at least 1/4" per foot (21mm/m) minimum.
Horizontal runs should not exceed 75% of the
vertical height of the vent pipe, or chimney, above
the fl ue pipe connection, up to a maximum length of
10' (3m). Horizontal portions of the venting system
shall be supported at minimum intervals of 4' (1.2m).
In Canada, support at minimum intervals of 3' (1m).
Observe the following precautions when venting the unit:
1. Use fl ue pipe of the same size as the fl ue connections
on the gas unit heater (See Table 1). All heaters should
be vented with appropriately sealed double wall or single
wall vent. Venting systems using Type B vent must comply
with National Fuel Gas Code, ANSI Z223.1 (NFPA54)
2. Each unit must have an individual vent pipe and vent
terminal. Unit must not be connected to other vent
systems or to a chimney.
3. The system must have a minimum vertical rise to ensure
that the vent pipe is under negative pressure. Install a
weather cap over the vent opening. A Breidert Type L,
Fields Starkap or equivalent vent cap must be supplied
by the customer for each power vented unit. Consideration
should be made for anticipated snow depth.
4. Through the wall venting for these appliances shall not
terminate over public walkways, or over an area where
the condensate or vapor could create a nuisance,
hazard, or could be detrimental to the operation of
regulators, relief valves, or other equipment.
4. Use as few elbows as possible.
5. Seal all vent pipe joints and seams to prevent
leakage. Use General Electric RTV-108, Dow
Corning RTV-732, or equivalent silicone sealant
with a temperature rating of 500 degrees F, or 3M
#425 aluminum foil tape (or equivalent).
6. Avoid running vent pipe through unheated spaces.
7. When this cannot be avoided, insulate the pipe to
prevent condensation of moisture on the walls of the
pipe.
8. Do not damper the fl ue piping. Failure to open such a
damper prior to operating the gas unit heater will result
in the spillage of fl ue gas into the occupied space.
9. Avoid installing units in areas under negative pressure
due to large exhaust fans or air conditioning. When
required, a flue vent fan should be installed in
accordance with the instructions included with the fan.
10. Vent connectors serving Category I and Category
II heaters shall not be connected into any portion of
mechanical draft systems operating under positive
pressure.
VERTICALLY VENTED UNIT HEATERS (CATEGORY I)
HORIZONTALLY VENTED UNIT HEATERS (CATEGORY I)
NOTICE: Horizontal Venting is only considered Category I for commercial applications if the unit is non-
condensing and there is negative vent pressure in the fl ue pipe. If fl ue pipe is under positive pressure, see
Horizontally Vented Unit Heaters (Category III) section.
5. The vent terminal must be at least 12 inches (305mm)
from the exterior of the wall that it passes through to
prevent degradation of the building material by fl ue gases.
6. Seal all vent pipe joints and seams to prevent leakage.
Use General Electric RTV-108, Dow-Corning RTV-732,
or equivalent silicone sealant with a temperature rating
of 500 deg. F, or 3M # 425 aluminum foil tape (or
equivalent). The vent system must be installed to prevent
collection of condensate. Pitch horizontal pipes downward
¼ inch per foot (21mm per meter) toward the outlet for
condensate drainage. Install a tee with a condensate
drain at the low point of the pipe (see Figure 8). As an
alternate, a 3/8 inch diameter hole may be drilled at the
low point of the pipe for condensate drainage.
7. Horizontal portions of the venting system shall be
supported at minimum intervals of 4 feet (1.2m) to
prevent sagging (in Canada, support at 3 foot (1m)
minimum intervals).
8. Avoid running vent pipe through unheated spaces. When
this cannot be avoided, insulate the pipe to prevent
condensation of moisture on the walls of the pipe.