Planning The Vent System; Condensate - A.O. Smith RESIDENTIAL GAS WATER HEATERS Instruction Manual

plannInG the vent sYsteM

Plan the route of the vent system from the exhaust elbow to the
planned location of the vent terminal.
1. Layout total vent system to use a minimum of vent pipe and elbows.
2. This water heater is capable of venting flue gases equivalent to
25' (7.6 m) of 2" pipe, 65' (19.8 m) of 3" pipe, or 128' (39.0 m) of
4" pipe as listed in Table 1.
Number of 2" Maximum
90° Elbows Pipe - ft. (m)
1 20 (6.1)
2 15 (4.6)
3 10 (3.0)
4 --
5 --
6 --
The minimum vent lengths for each of the pipe sizes is one 90° plus
2' (61 cm) of straight pipe and the appropriate termination.
note: The equivalent feet (m) of pipe listed above are exclusive
of the termination. That is, the termination, with an installed
screen, is assumed to be in the system and the remainder of the
system must not exceed the lengths discussed above.
3. The exhaust elbow assembly is designed to accept only straight
sections of 2" pipe. To start, a minimum of 2" (5.1cm) of 2" pipe
must be inserted and glued to the exhaust elbow assembly if
utilizing 3" or 4" vent pipe. Use the same method with the blower
inlet if a direct vent configuration is utilized.
If using 2" inch vent pipe:
A minimum of 2" (5.1cm) diameter vent pipe must be attached
to the exhaust elbow assembly. The total system cannot exceed
the lengths discussed above, where each elbow is equal to 5
equivalent feet (1.5m) of straight pipe.
If using 3" or 4" inch vent pipe:
Two inches (5.1cm) of 2" pipe must be attached to the exhaust
elbow assembly before adding a reducer to acquire the desired
pipe diameter. An appropriately sized 45 degree elbow (supplied
locally-a schedule 40 DWV) vent terminal must be obtained with
an equivalent screen (supplied in vent kit). The total system cannot
exceed the equivalent pipe lengths discussed above where each
elbow is equal to 5 feet (1.5m) of straight pipe (3" vent pipe) or 8
feet (2.4m) of straight pipe (4" vent pipe).
u.s. InstallatIons:
note: This unit can be vented with PVC pipe materials (Cellular Core
ASTM-F891; DWV ASTM-D2665 or CSA B181.2; Schedule 40, 80,
120 ASTM-D1785 or CSA B137.3; or SDR Series ASTM-D2241 or
CSA B137.3), CPVC pipe materials (CPVC41 ASTM-D2846 or CSA
B137.6; Schedule 40, 80 ASTM-F441 or CSA B137.6; or SDR Series
ASTM-F442), ABS pipe materials (Schedule 40 DWV ASTM-D2661
or CSA B181.1 or Schedule 40 DWV Cellular Core ASTM-F628). The
fittings, other than the TERMINATION should be equivalent to PVC-
DWV fittings meeting ASTM D-2665 (Use CPVC fittings, ASTM F-438
for CPVC pipe and ABS fittings, ASTM D-2661/3311 for ABS pipe).
If CPVC or ABS pipe and fittings are used, then proper cement must
be used for all joints, including joining the pipe to Termination (PVC
Material). If local codes do not allow the use of the PVC termination
when a material other than PVC is used for venting, then an equivalent
fitting of that material may be substituted if the screen in the PVC
terminal is removed and inserted into the new fitting.
canadian Installation of this water heater must comply with can/
CSA B149.1 - Natural Gas and Propane Installation Code which
requires the vent system components be certified to ULC S636.
This water heater has been design certified to be vented with PVC
pipe certified and marked as complying with ULC S636. This water
heater is supplied with a 2 inch 22.5 degree termination elbow that is a
special fitting that must be used with the appliance. Any outlet piping,
fittings and glue used to vent this appliance that is not supplied by the
manufacturer must comply with the ULC S636 requirements.
PVC Materials should use ASTM D-2564 Grade Cement; CPVC
Materials should use ASTM F-493 Grade Cement and ABS
Materials should use ASTM D-2235 Grade Cement.
If the water heater is being installed as a replacement for an existing
power vented heater in pre-existing venting, a thorough inspection
TABLE 1
3" Maximum 4" Maximum
Pipe - ft. (m) Pipe - ft. (m)
60 (18.3) 120 (36.6)
55 (16.8) 112 (34.1)
50 (15.2) 104 (31.7)
45 (13.7) 96 (29.3)
40 (12.2) 88 (26.8)
35 (10.7) 80 (24.3)
of existing venting system must be performed prior to any installation
work. Verify that correct material as detailed above has been used,
and that the minimum or maximum vent lengths and terminal location
as detailed in this manual have been met. Carefully inspect the entire
venting system for any signs of cracks or fractures, particularly at
joints between elbows and other fittings and straight runs of vent
pipe. Check system for signs of sagging or other stresses in joints as
a result of misalignment of any components in the system. If any of
these conditions are found, they must be corrected in accordance with
the venting instructions in this manual before completing installation
and putting the water heater into service.
note: a. For water heaters in locations with high ambient
temperatures (above 100°F) it is recommended that CPVC or
ABS pipe and fittings be used. B. A 22.5 degree elbow (2" vent
pipe) or a 45 degree elbow (3" and 4" vent pipe) with an installed
screen VENT TERMINAL must be used in all cases.
4. There will be some installations where condensate will be formed
in the horizontal runs of the vent system. This condensate will
run into the condensate elbow. The water heater is shipped with
a condensate hose that attaches to the condensate elbow. No
other tee or fitting is required.

condensate

This water heater is a condensing unit and requires a drain to be located in
close proximity to allow the condensate to drain safely. The condensate
drains from the unit at the exhaust tee located at the bottom of the unit
(see figure 16). Condensate from this water heater is mildly acidic.
Please note that some local codes require that condensate is treated
by using a pH neutralizing filter prior to disposal.
Caution must be used to ensure that the drain is free and clear of debris
and will not allow backflow through the condensate hose. Consideration
must be given to avoid freezing of the condensate lines which could
result in excessive build up of condensate inside the water heater.
Waterproof heat tape may be required to prevent freezing of the condensate
lines. Please ensure that the outlet of the condensate drain does
not create a slippery condition which could lead to personal injury.
condensatIon warnInG: thIs water heater Is a condensInG
unIt and requIres a draIn to Be located In close proXIMItY
to allow condensate to draIn safelY. the condensate
draIns froM unIt at the eXhaust elBow located at
BottoM of unIt. note: It Is IMportant that the condensate
hose not Be elevated aBove the eXhaust elBow, see
FIGURE 16. CONDENSATE BUILD-UP WILL BLOCK THE EXHAUST
outlet, whIch wIll cause IMproper operatIon.
19
FIGURE 16.