Venting Through Closed Spaces
1/4" per foot | Wall Thimble | |
downward slope | ||
| ||
|
| |
|
|
Fire
Stop
Vent Pipe
Ceiling |
|
Board |
|
Inspection | Inspection |
Access Panel #1 | Access |
| |
| Panel #2 |
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 in2 (103 cm2) opening should be provided every 10 ft (3 m).
CAUTION: Ensure that the appliance vent adapter is securely attached to the water heater collar.
Exhaust
Flow
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.
● 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 |
High Temp. Sealant 
Appliance
Vent Adapter
A 
Clamp
● 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. |
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. |
B 
Collar
Water Heater
● Apply 1/4” (6 mm) wide bead of high |
temperature silicone (500°F [260°C]) |
around outside of heater collar “B”. |
NOTICE: Follow the appliance vent adapter manufacturer’s instructions.
CAUTION: Condensate is known to be acidic; refer to local, state (provincial) or federal codes for proper handling and discharge methods.
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.
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.
11