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TFTN 085-199
The use of double-wall vent or insulated material for the combustion air intake pipe is
recommended in cold climates to prevent the condensation of airborne moisture on the incoming
combustion air pipe.
4.6
Exhaust and Air-Intake Vent Size & Length
TFTN085-285 models are equipped with 3 in. diameter exhaust and air intake collars and can be vented in 3 in. diameter
pipe up to a maximum of 150 ft. equivalent for each the exhaust and the air-intake vent. Alternatively, TFTN085-199
models (ONLY) can be vented with 2 in. diameter pipe up to a maximum of 100 ft. equivalent for each the exhaust and
air-intake vent.
NOTE: a reducing coupling MUST BE USED when transitioning from 3 in. to 2 in. vent pipe. DO NOT use reducing bushings.
TFTN340-399 models are equipped with 4 in. diameter exhaust and air intake collars and can be vented in 4 in. diameter
pipe up to a maximum of 150 ft. equivalent for each the exhaust and the air-intake vent.
Use Tables 4-4 and 4-5 to determine the maximum pipe length and number of fittings that can be used to make up the
exhaust and air-intake venting.
Table 4-4 Allowable Vent Size & Length
Pipe Size
Models
(in.)
TFTN085-199
2
TFTN285
2
TFTN085-285
3
TFTN340-399
3
TFTN340-399
4
* Lengths represent the allowable equivalent pipe length; see Table
4-5 for a list of equivalent lengths of fittings.
4.7
Direct Vent Installation
When installed as a Direct Vent boiler the combustion air intake must also be piped directly to the outdoors using the
methods described in this section and in accordance with the National Fuel Gas Code, ANSI Z223.1 (U.S.) or CSA B149.1
(Canada) and local requirements.
Termination Options
The venting system of the TFTN may be terminated using field supplied piping to construct a "Two-Pipe" termination; see
Figures 4-2(a)(e)(h), 4-3(a), 4-4(a)(d), 4-5, 4-6 and 4-7. Alternatively, the venting may be terminated using a factory kit
selected from Table 4-7; see Figures 4-2(b)(c)(d)(f)(g), 4-3(b)(c)(d) and 4-4(b)(c).
Sidewall Termination - Due to potential moisture loading (build-up) along the exterior wall,
sidewall venting may not be the preferred venting option. Refer to Figures 4-2(e)(f)(g)(h) and 4-
4(a)(b)(c)(d) for roof top venting options.
When sidewall venting, it is recommended to reduce the diameter of the exhaust vent at the
termination, to increase exhaust gas velocity, further directing it away from the building. The final
6 ft. of exhaust vent can be reduced to a diameter of 2 in. for models TFTN085-285, and 3 in. for
models TFTN340-399.
The vent for this appliance shall not terminate over public walkways; or near soffit vents or crawl
space vents or other area where condensate of vapor could create a nuisance or hazard or cause
property damage; or where condensate or vapor could cause damage or could be detrimental to
the operation of regulators, relief valves, or other equipment.
Extra precaution must be taken to adequately support the weight of the Exhaust/Air Intake piping
in applications using roof-top terminations. Failure to follow these instructions may result in
venting or boiler component failure resulting in flue gas spillage leading to property damage,
serious injury or death.
Exhaust Vent
Air-Intake Vent
Length (ft.) *
Length (ft.) *
6 - 100
0 - 100
0 - 6
NA
6 - 150
0 - 150
0 - 6
NA
6 - 150
0 - 150
Installation and Operation Manual
Table 4-5 Equivalent Length of Fittings
Fitting
90 Degree Elbow
45 Degree Elbow
Coupling
Concentric Vent
Each foot of vent pipe
Equivalent
Length (ft.)
5
3
0
3
1
19
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