Venting Terminations And Sizing; Vent Screen Installation - A.O. Smith RESIDENTIAL GAS WATER HEATERS Installation And Operating Manual

Venting terminations and sizing

•
Refer to Figure 34 and Table 2 for vent pipe materials
and sizing. Examples of the vent terminations are
shown in Figures 35 & 36. If the installation requires
a vent riser, suitable drainage must be provided to
ensure condensation does not accumulate. Termination
through a roof is shown Figure 37.
•
40, 50 and 60 gallon heaters with rated inputs of 50k
Btu/hr or less are supplied with a 2"-3" rubber coupling
to attach the venting to the blower and a 2", 45° vent
termination elbow.
For heaters with rated inputs of 50k Btu/hr or less:
with 2 in. venting (short)
VENT LENGTH LESS THAN OR
EQUAL TO 20 EQUIVALENT FT.
(6.1 METRES) USE THIS SCREEN
(SUPPLIED).
with 3 in. venting
VENT LENGTH LESS THAN OR
EQUAL TO 50 EQUIVALENT FT.
(15.2 METRES) USE THIS SCREEN
(SUPPLIED).
with 4 in. venting
VENT LENGTH GREATER THAN
125 EQUIVALENT FT.
(38.1 METRES) USE THIS SCREEN
(SUPPLIED).
Figure 32
with 2 in. venting (long)
VENT LENGTH GREATER THAN
20 EQUIVALENT FT.
(6.1 METRES) USE THIS SCREEN
(SUPPLIED).
with 3 in. venting
VENT LENGTH GREATER THAN
50 EQUIVALENT FT.
(15.2 METRES) USE THIS SCREEN
(SUPPLIED).
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•
50 and 75 gallon heaters with a rated input of 60k Btu/
hr or more are supplied with a 3"-3" rubber coupling
to attach the venting to the blower and a 3", 45° vent
termination elbow.
•
Supplied with this heater are several vent termination
screens (see Figures 32 & 33).
Installed in the vent termination elbow, the vent screen
is required to keep foreign objects, rodents and small
birds from entering the venting system. These screens
have been sized to ensure maximum energy effi ciency of
the vent system based on the "equivalent length" of the
vent piping. CHOOSE ONLY the ONE SCREEN THAT
MATCHES YOUR VENTING CONFIGUARATION (see
Figures 32 & 33). How to determine the "equivalent length"
is shown in Figure 34 and in Table 2.

Vent screen installation

•
Install the appropriate vent screen into the vent
termination elbow.
•
Gently push the screen into the termination elbow until
it sits against the inside shoulder.
•
The metal wire screens are self-securing.
•
Plastic screens must be secured with (2) drops of
silicone sealant. This will allow for easy removal for
inspection and cleaning.
For heaters with rated inputs of 60k Btu/hr or more:
with 3 in. venting (short)
VENT LENGTH LESS THAN OR
EQUAL TO 20 EQUIVALENT FT.
(6.1 METRES) USE THIS SCREEN
(SUPPLIED).
with 4 in. venting
VENT LENGTH GREATER THAN
50 EQUIVALENT FT.
(15.2 METRES) USE THIS SCREEN
(SUPPLIED).
Figure 33
with 3 in. venting (long)
VENT LENGTH GREATER THAN
20 EQUIVALENT FT.
(6.1 METRES) USE THIS SCREEN
(SUPPLIED).
31