Vent Pipe Connection To Blower; Coupling Installations According To Vent Sizes - A.O. Smith GPVX 75L Series Installation And Operating Manual

75mm (3 in.)
MIN. LENGTH
A VENT USED IN A
SPECIAL VENTING
SYSTEM WITH POSITIVE
VENT PRESSURE AND
PASSING THROUGH A
ROOF SHALL EXTEND
AT LEAST 450mm (18 in.)
ABOVE THE HIGHEST
POINT WHERE IT PASSES
THROUGH THE ROOF
SURFACE AND ANY
OTHER OBSTRUCTION
WITHIN A HORIZONTAL
DISTANCE OF 450mm
(18 in.). A VERTICAL
VENTING SYSTEM MUST
BE SUPPORTED EVERY
1.5m (5 ft.).
Figure 30

Vent pipe connection to blower

1. The vent piping connects into the rubber coupling
located on the top of the blower assembly. This
coupling includes gear clamps to connect the venting
to the blower. These connections must be properly
seated and tightened to prevent the leakage of flue
gases into the area. See Figure 31 thru Figure 33.
2. The water heater is supplied with a 3" rubber
coupling to accept the vent pipe and is required in all
installations. Do not attempt to connect the vent piping
directly to the blower without using the rubber coupling.
Note: Polypropylene vent systems require separate
adaptor.
3. Before installing clean and lightly sand the end of the
plastic vent piping that will connect into the rubber
coupling. For polypropylene vent systems follow
manufacturer's instructions.
4. Loosen the upper clamp on the rubber coupling
and insert the sanded end of the vent piping a full
32mm (1-1/4 in.). Do not use glue or sealant in the
rubber coupling. Check that there is no stress on the
connection or the vent piping that may be caused by
twisting or bending.
5. Tighten the upper clamp so that the vent piping is
firmly secured in the coupling and is gas tight. Do not
over tighten or cause distortion of any of the parts.
Ensure the bottom of the rubber coupling is firmly
seated on the blower outlet and that the lower gear
clamp is also secure. Check to ensure there is no
distortion or movement of the clamped assembly once
it is completed.
6. If the outlet vent pipe is to be turned horizontally
directly off the blower, a 75mm (3 in.) long section
vent pipe shall be used to connect the elbow to the
rubber coupling (see Figure 33). For heaters installed
with the option using the first 1.5m (5 ft.) being CPVC
venting, the first elbow is in addition to the 1.5m (5 ft.)
rule (see "Venting").
100271597
TERMINATION
MAY BE 90°
ELBOW
450mm
RODENT
(18 in.) OR
SCREEN
ABOVE
(INSTALL
ANTICIPATED
INTO
SNOW LEVEL
ELBOW)
ROOF
LINE
CAUTION
Property Damage Hazard
• Do not overtighten the top and bottom gear clamps of the
rubber coupling.
• Do not apply solvent cement or silicone to the rubber
coupling connection.

Coupling installations according to vent sizes

* HEATERS
EQUIPPED WITH
THE 181° CONTROL
MUST USE CPVC
PIPING FOR THE
3" RUBBER
FIRST 1.5m (5') OF
COUPLING
VENTING.
(SUPPLIED)
BLOWER
Figure 31
* HEATERS
EQUIPPED WITH
THE 181° CONTROL
MUST USE CPVC
PIPING FOR THE
FIRST 1.5m (5') OF
3" RUBBER
VENTING.
COUPLING
(SUPPLIED)
BLOWER
Figure 32
3" VENT
PIPE*
(SUPPLIED)
3" VENT
PIPE*
(SUPPLIED)
BLOWER
* HEATERS
EQUIPPED WITH
THE 181° CONTROL
MUST USE CPVC
PIPING FOR THE
FIRST 1.5m (5') OF
VENTING.
Figure 33
3" VENT
PIPE
4" VENT
PIPE*
3"-4"
ADAPTER*
(FIELD
SUPPLIED)
3" VENT
PIPE*, 75mm
(3 in.) MAX
LENGTH
3" ELBOW
**(FIELD
SUPPLIED)
3" RUBBER
COUPLING
(SUPPLIED)
29