Venting Rules and Guidelines
1. Prevailing Winds: Ensure the vent is located where it will not be exposed to normal prevailing winds.
2. Combustion Air-inlet Contamination: Air for combustion must be drawn from an area free of dust and
contaminants. Combustion air containing chemicals such as chloride, fluoride, bromine or iodine or dust and
debris will cause corrosion damage of the heat exchanger voiding your NTI warranty. Refer to Table 4-1 for
a list of corrosive products and contaminants sources to avoid.
3. Vertical Separation: The exhaust must be a minimum of 18 in. above the air inlet, and the air inlet must
always be a minimum of 12 in. plus snow allowance above any surface that will support snow. (Two feet
plus snow allowance is highly recommended). Consult your weather office for the maximum typical
snowfall for your region.
Example: New Brunswick Canada - typical maximum snowfall is 19 in., thus the inlet must be (12”+19”) =
31 in. above grade and exhaust must be (31”+18”) = 49” above grade.
4. Horizontal Separation: The horizontal distance between the inlet and exhaust must be a minimum of 4”
[102 mm] center to center.
5. Wall Flashing: Under normal operating conditions this boiler will produce a plume of white gases, and
should be taken into consideration when selecting an adequate location. A 36 in. diameter stainless, plastic,
or vinyl shield can be used to flash the exterior of the residence.
6. Flue Gas Hazard: Position the vent termination where vapors cannot make accidental contact with people
and pets or damage nearby shrubs and plants.
7. Elbow Extensions: Elbows on outside of wall must be no more than ½ in. away from the wall.
8. Vent Sloping: All indoor exhaust piping must be on a slope back to the boiler a minimum of ¼ in. per
linear foot of vent. For applications where excessive condensation is possible ½ in. per linear foot is
recommended.
9. Vent Supports: Where required Vent and Air-inlet piping shall be secured to the wall for more rigidity. All
interior vent pipe shall be supported a minimum of every 36 in..
10. Roof Exhaust: In all roof applications the discharge must point away from the pitch of the roof.
11. Roof Flashing: Install adequate flashing where the pipe enters the roof, to prevent water leakage.
12. Rain Cap: Install and seal a rain cap over existing chimney openings, in vacant chimney applications.
13. Venting Below Grade: For installations that exit the wall below grade refer to Figure 4-4.
14. Vent Screens: Install factory supplied vent screens on the outside of the last elbow for both the inlet and
exhaust vent terminal elbows. Install the screen into the female opening of the elbow, and then cut a small
piece of pipe to sandwich the screen into the elbow. NOTE: ensure the small piece of pipe cut, does not
extend past the end of the elbow. Two screens are provided in the package. See Figures 4-2 and 4-3.
15. Condensate Hazard: Do not locate vent over public walkways, driveways or parking lots. Condensate
could drip and freeze resulting in a slip hazard or damage to vehicles and machinery.
16. Warning Plate: For Sidewall Venting, install the warning plate “Gas Vent Directly Below”, directly above
(within 4 ft. vertically) the location of the air-inlet pipe, so it is visible from at least 8 ft away. See Figure 4-
2.
17. Wall Thickness: Direct vent terminations are designed to work with any standard wall thickness.
Installation guidelines for min/max wall thickness are as follows: Min. = 1 in., Max. = 60 in..
18. Venting Options: Due to potential moisture loading (build-up) along the exterior wall, sidewall venting
may not be the preferred venting option. Refer to Figure 4-3 for roof top venting options.
The vent for this boiler 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 Vent/Air-inlet
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.