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The inlet and exhaust pipes on the top of the cabinet should be the diameter and material indicated in the Venting Specifications
Table above. It is very important that you plan the location properly to eliminate long pipe runs and excessive fittings. Inlet pipe size
must not be reduced. Do not combine the inlet air or exhaust with any other inlet or exhaust pipe including either to an additional
similar appliance, unless you have purchased an engineered Common Venting System from Armstrong Hot Water, Inc. The joints
must be properly cleaned, primed and cemented if plastic, and sealed per the manufacturer’s instructions if stainless. The piping
must also be properly supported as per Local and National Standard Plumbing Codes. It is important that the piping must be clean
and free from burrs, debris, ragged ends and particles of PVC (if applicable).
Exhaust piping should be sloped back to the connection on the ABH, at least 1/4” per foot to remove additional condensate that
forms within the pipe. The total combined length of pipe (intake piping plus exhaust piping added together) including elbow
allowances intake and exhaust should not exceed the length shown in the vent table. The minimum combined vent length should not
be less than a combined length of 6’ (1.8m) plus two 90° elbows. Choose your vent termination locations carefully. You must also
make certain that exhaust gas does not re-circulate back into the intake pipe. You must place them in an open area and follow the
following guidelines:
1. Never vent into a walkway, patio area, alley or otherwise public area less than 7'(2.1m) from the ground. (See detail below
references Fig. A.12.9 in the National Fuel Gas Code 2009 “Exit Terminals of Mechanical Draft and Direct-Venting Systems;” see
Figure 4.1.
2. Never vent over or under a window or a doorway where the exhaust plume or condensation liquid will cause obtrusive or
dangerous conditions. (Refer to National Fuel Gas Code, CAN B149).
3. Never install a heat saver or similar product to capture waste heat from exhaust.
4. Always have a vent location at least 12" (305mm) above maximum snow level.
5. Always have vent a minimum of 24" (609mm) above ground level, away from shrubs and bushes.
6. Follow local gas codes in your region or refer to National Fuel Gas Code, Can B149.
7. Always have at least 36" (914mm) distance from an inside corner of the outside walls.
8. Maintain at least 48" (1219mm) clearance to electric, gas meters, windows, exhaust fans, chimneys, inlets or mechanical vents.
9. VERY IMPORTANT!
The inlet air connection must be connected to outside air and should be located no closer than 8" (203mm)
and no further than 24" (809mm) t othe exhaust.
10. Always place screens in all openings in intake and exhaust to prevent foreign matter from entering the ABH.
11. The vent intake and exhaust must be properly cleaned and glued if plastic, and sealed per the manufacturer’s directions if
stainless for a pressure tight joint. Several methods for venting the ABH can be found in Figures 4.2 through 4.6 of this section. Use
these layouts as guidelines: certain site conditions such as multiple roof lines/pitches may require venting modifications (consult
Armstrong Hot Water, Inc.).
NOTICE! The following are code restrictions for the location of the flue gas vent terminal.
Compliance to these requirements doesn’t insure a satisfactory installation; good common
sense must also be applied. It is important to make sure that exhaust gases are not
recirculated into the inlet air of the ABH. If there is any doubt, contact the factory BEFORE
installing.
Venting - continued
Table 4.2 Equivalent Feet
Fittings or Piping
Equivalent Feet (m)
90 degree elbow
5' (1.5)
45 degree elbow
3' (0.9)
Coupling
0 (0)
Air inlet elbow
6' (1.8)
Exhaust coupling
1'(0.3)
