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Venting Through Closed Spaces
If the vent piping passes through a closed space, a minimum clearance of
8” (20 cm) when installed horizontally or 6”
(15 cm)
when installed
vertically should be maintained between the vent pipe and combustibles
and noncombustibles. Be sure to follow local codes and vent
manufacturer’s installation instructions.
For maintenance and inspection purposes, the following access panels are
required.
● Two (2) inspection access panels large enough to allow access for
venting inspection. One (1) of these access panels should be close
to where the vent pipe enters the ceiling. The other access panel
should be near the vent termination.
● A ventilation access panel with a 16 in
2
(103 cm
2
) opening should
be provided every 10 ft (3 m).
downward slope
1
/
4" per
f
oot
Ceiling
Vent Pipe
Wall Thimble
Board
Inspection
Fire
Stop
Access Panel #1
Inspection
Access
Panel #2
Appliance Vent Adapter
The water heater must be installed
with a UL 1738 approved Category III
Stainless Steel appliance vent adapter.
Read the following instructions before
installation.
● Test fit the adapter over the water heater
collar before proceeding. Adjust clamp as
needed.
● With an alcohol wipe, clean inside
surface
“A” of adapter and outside surface “B” of
heater collar.
● Apply 1/4” (6 mm) wide bead of high
temperature silicone (500°F [260°C])
around outside
of heater collar “B”.
● Slide adapter end “A” down over heater
collar “B” as far as it will go.
● Tighten the clamp around the collar.
● Inspect the inside of the adapter to verify
that the collar and adapter are sealed. If
more sealant is required, apply sealant to a
flat tool, then spread around the collar edge
on inside
of adapter.
● Ensure that the clamp does not interfere
with the damper shaft.
NOTICE: Follow the appliance vent adapter
manufacturer’s instructions.
Appliance
Vent Adapter
Water Heater
Exhaust
Flow
A
B
High Temp.
Sealant
Collar
Clamp
Draining the Condensate
Provision should be made to collect and
dispose of condensate from venting systems.
When a water heater is vented horizontally,
the vent pipe can have a DOWNWARD or
UPWARD slope towards the termination. If
an UPWARD slope is used, a condensate trap
must be installed as close as practical to the
water heater in order to prevent condensate
from draining back into the water heater. See
Examples A and B on page 14 for
DOWNWARD and UPWARD slope for
horizontally vented water heaters.
When a water heater is vented vertically, an
UPWARD slope must always be used. A
condensate trap must be installed in the
horizontal section of the vent and as close
as practical to the water heater in order to
prevent condensate from draining back into
the water heater. See the diagram on page 15
showing UPWARD slope for vertically
vented water heaters.
Always attach a drain hose to the drain fitting
and plumb the hose to a sanitary sewer drain.
A high temperature silicone tubing suitable for
use with acidic condensate and appropriate for
the temperature range should be used.
The drain tube is fashioned into a “pigtail” trap
and must be filled with water to prevent flue
gases from emitting into the building prior to
operating the appliance.
CAUTION: Condensate
must drain away from the
water heater and should
not be allowed to drain
back into any part of the
vent system.
WARNING: Failure to
provide a vent condensate
drain close to the appliance
could allow acidic flue gas
condensate to enter into
appliance flueways, causing
premature failure of the
appliance.
CAUTION: Condensate
is known to be acidic; refer
to local, state (provincial)
or federal codes for proper
handling and discharge
methods.
11
CAUTION: Ensure that the
appliance vent adapter is
securely attached to the
water heater collar.