VENTING
PART 8: VENTING, COMBUSTION AIR & CONDENSATE REMOVAL (CONTINUED)
b. Transitions should always be made in vertical sections of pipe to prevent the condensate from
pooling in the vent pipe.
c. If the transition occurs at a distance greater than 15 equivalent feet from the water heater, the
maximum equivalent length will be reduced. See Table 8-8.
G. EXHAUST VENT AND INTAKE AIR PIPE INSTALLATION
1. Use only solid PVC or CPVC pipe. FOAM CORE PIPING IS NOT APPROVED. Refer to chart Section
8-C.
2. Remove all burrs and debris from joints and fittings.
3. All joints must be properly cleaned, primed, and cemented. Use only cement and primer approved
for use with the pipe material. Cement must conform to ASTM D2564 for PVC and ASTM F493
for CPVC pipe.
4. Horizontal lengths of exhaust vent must slope back towards the water heater not less than ¼" per
foot to allow condensate to drain from the vent pipe. If the exhaust pipe must be piped around
an obstacle that results in the creation of a low point, condensate will collect in this low point and
form a blockage. This condensate must be drained away using a field-installed condensate drain
assembly as shown. (See Fig. 8-10)
5. All piping must be fully supported. Use pipe hangers at a minimum of 4 foot intervals to prevent
sagging of the pipe where condensate may form.
6. Do not use the unit to support any piping.
7. A screened straight coupling is provided with the unit for use as an outside exhaust termination.
Table 8-8: Vent Termination Kits
TEL = Total Equivalent Length
Table 8-7: Vent Run Transition
Vent
Connection
Reducing
Coupling
Vent
Transition
2" 3" x 2" 3"
3" 4" x 3" 4"
Transition
Point
(ft from
water heater)
TEL of
Standard
2" Vent
Pipe (ft)
TEL of
Oversized
2", 3" or 4"
Vent Pipe (ft)
Maximum
TEL of all
Vent Pipe (ft)
15 30 95 125
20 40 77-1/2 117-1/2
25 50 60-1/2 110-1/2
30 60 43 103
35 70 26 96
40 80 8-1/2 88-1/2
None 85 0 85
n
WARNING
All joints of positive pressure vent systems must be sealed completely to prevent
leakage of flue products into the living space.
33
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