25
Venting
General
Flue Exhaust Tee
An optional Flue Exhaust Tee is available to facilitate
horizontal venting. Any reference to horizontal venting
that exits the back of the heater requires this tee. Refer
to Table J for the appropriate kit for your model.
CAUTION:
Proper installation of flue venting is criti-
cal for the safe and efficient operation of the heater.
Table J: Flue Exhaust Tee Kits
Model
Diameter
Order Number
399B–499B
6”
011839
649B, 749B,
899B
8”
011840
989B
10”
011841
1259B, 1529B
12”
011842
1799B, 1999B,
2069B
14”
011843
2339B
16”
011844
Category IV
– A heater which operates with a positive
vent pressure and with a vent gas temperature that
may cause excessive condensate production in the
vent.
See Table K for appliance category requirements.
Support of Vent Stack
The weight of the vent stack or chimney must not rest
on the heater vent connection. Support must be pro-
vided in compliance with applicable codes. The vent
should also be installed to maintain proper clearances
from combustible materials.
Barometric Damper
A barometric damper may be required when vent
heights exceed 25 feet or when the draft is greater
than -0.08 in. WC. In these installations, a barometric
damper (single or double acting) is recommended.
The damper should be installed NO CLOSER than 18
in. from the discharge of the unit and no closer than 18
in. from a combustible ceiling. The damper can be
installed in horizontal or vertical runs of vent pipe as
necessary. Installation in a bull-head tee is acceptable
as shown in the NFGC.
The weights on the damper should be adjusted per the
damper manufacturer’s instructions for proper opera-
tion.
Appliance Categories
Heaters are divided into four categories based on the
pressure produced in the exhaust and the likelihood of
condensate production in the vent.
Category I
– A heater which operates with a non-pos-
itive vent static pressure and with a vent gas
temperature that avoids excessive condensate pro-
duction in the vent.
Category II
– A heater which operates with a non-pos-
itive vent static pressure and with a vent gas
temperature that may cause excessive condensate
production in the vent.
Category III
– A heater which operates with a positive
vent pressure and with a vent gas temperature that
avoids excessive condensate production in the vent.
NOTE:
For additional information on appliance
categorization, see appropriate ANSI Z21 Standard
and the NFGC (U.S.), or B149 (Canada), or
applicable provisions of local building codes.
CAUTION:
When condensate traps are installed,
condensate must be routed to an appropriate
container for neutralization before disposal, as
required by local codes.
WARNING:
Contact the manufacturer of the vent
material if there is any question about the appliance
categorization and suitability of a vent material for
application on a Category III or IV vent system.
Using improper venting materials can result in
personal injury, death or property damage.
NOTE:
During winter months check the vent cap
and make sure no blockage occurs from build-up of
snow or ice.
