LAARS U.H.E. - Installation Manual - Manual (Page 25)

NOTICE
This unit can be vented using only PVC (Class 160, ASTM D-2241 Schedule 40, ASTM D-1785;
or Cellular Core Schedule 40 DWV, ASTM F-891), Schedule 40 CPVC (ASTM F-411), or ABS
(ASTM D-2661) pipe. The fittings, other than the TERMINATIONS should be equivalent to PVC-
DWV fittings meeting ASTM F-2665. (Use CPVC fittings, ASTM F-438 for CPVC pipe and ABS
fittings, ASTM D-266/3311 for ABS pipe.) If CPVC or ABS pipe and fittings are used, then the
proper cement must be used for all joints, including joining the pipe to the Termination (PVC
material). PVC materials should use ASTM –D2564 grade cement; CPVC materials should use
ASTM F-493 grade cement; and ABS materials should use ASTM D-2235 grade cement.
For water heaters in locations with high ambient temperatures (above 100°F) and/or insufficient
dilution air, it is recommended that CPVC or ABS pipe and fittings (MUST USE SUPPLIED
VENT TERMINAL) be used.
Horizontal Installation:
In a horizontal application, it is important that condensate not be allowed to buildup in the exhaust vent pipe. To
prevent this from happening, the pipe should be installed with an slight upward slope. The vent system must be
supported every 5 feet of vertical run and every 3 feet of horizontal run of vent pipe length.
CAUTION
Failure to properly support the vent piping with hangers and clamps may result in damage to the water heater
or venting system.
Stress levels in the pipe and fittings can be significantly increased by improper installation. If rigid pipe clamps
are used to hold the pipe in place, or if the pipe cannot move freely through a wall penetration, the pipe may be
directly stressed, or high thermal stresses may be formed when the pipe heats up and expands. Install accordingly
to minimize such stresses.
Follow the following procedure to vent through the wall:
1. Cut one 3 1/2 in. (8.9 cm) diameter hole (for 3” (7.6 cm) diameter pipe) or 4 ½” (11.5 cm) diameter hole
(for 4” (10.2 cm) diameter pipe).
2. Use the proper PVC cement or sealant to secure the 90° exhaust vent terminal provided with the water
heater to the plastic pipes. The distance between the back edge of the 90° exhaust vent terminal and the
exterior wall (see Figure 16) must be 6 inches (13.0 cm). Use the proper cement and assembly
procedures to secure the vent connector joints between the terminal and the blower outlet. Provide
support brackets for every 3 feet (1.0 m) of horizontal vent.
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