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PREPARE ROOF PENETRATIONS
1. Air pipe penetration:
a. Cut a hole for the air pipe. Size the air pipe hole as close
as desired to the air pipe outside diameter.
2. Vent pipe penetration:
a. Cut a hole for the vent pipe. For either combustible or
noncombustible construction, size the vent pipe hole with
at least a 1/2 inch clearance around the vent pipe outer
diameter:
•
4½ inch hole for 3 inch vent pipe.
•
5½ inch hole for 4 inch vent pipe.
•
7½ inch hole for 6 inch vent pipe.
b. Insert a galvanized metal thimble in the vent pipe hole.
3. Space the air and vent holes to provide the minimum spacing
shown in Figure 43 on Page 31.
4. Follow all local codes for isolation of vent pipe when passing
through floors, ceilings, and roofs.
5. Provide flashing and sealing boots sized for the vent pipe
and air pipe.
MULTIPLE VENT/AIR TERMINATIONS
1. When terminating multiple XP water heaters, terminate each
vent/air connection as described in this manual (Figure 45).
Terminate all vent pipes at the same height and all air pipes at
the same height to avoid possibility of severe personal injury,
death, or substantial property damage.
2. Place roof penetrations to obtain minimum clearance of 12
inches between edge of air intake elbow and adjacent vent
pipe of another water heater for U.S. installations (see Figure
45).
3. The air inlet of an XP water heater is part of a direct vent
connection. It is not classified as a forced air intake with
regard to spacing from adjacent water heater vents.
Figure 45. Vertical Terminations with Multiple Water Heaters
Figure 46. Alternate Vertical Terminations with Multiple
Water Heaters
