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SUF SERVICE HANDBOOK
INSTALLATION
Technical Training Department State Water Heaters
STC-077
4 Ashland City, Tennessee © 2004
VENTING
Equivalent Feet of Pipe Intake or Exhaust
4-inch PVC may be used for a MAXIMUM intake of ONE HUNDRED TWENTY (120) EQUIVALENT
FEET and a MAXIMUM exhaust of ONE HUNDRED TWENTY (120) EQUIVALENT FEET. The
maximum number of 90° elbows with the 4-inch venting is six (6) on the intake and six (6) on the
exhaust. A 90° elbow is equal to five (5) equivalent feet of pipe. One (1) 90° elbow is equal to two
(2) 45° elbows. Any venting configuration using less than 50 equivalent feet should use 3-inch vent-
ing. See Vent Length Table.
The 3-inch venting terminals (provided) must be used with the 4-inch venting by adding 4 x 3
reducing coupling at the venting terminals. A reducing coupling is also needed immediately after
the condensate elbow (exhaust) and immediately before the 3-inch blower adapter (intake) if direct
venting is installed. See Vent Length Table.
DIRECT VENTING
The air intake provided on the unit contains a mesh screen (see Figure below) to prevent large par-
ticles from entering the unit.
VENT LENGTH TABLE
NUMBER OF 90°
ELBOWS
3” MINIMUM
PIPE (FEET)
3” MAXIMUM
PIPE (FEET)
4” MAXIMUM
PIPE (FEET)
ONE (1)
745115
TWO (2) 7 40 110
THREE (3) 7 35 105
FOUR (4) 7 30 100
FIVE (5) 7 -- 95
SIX (6) 7 -- 90
3” (7.6CM) 45° PVC ELBOW WITH MESH SCREEN
WARNING
WHEN THE UNIT IS TO
BE SETUP AS A DIRECT VENT, THE
MESH SCREEN MUST BE REMOVED.
THE INLET VENT PIPE MAY THEN BE
GLUED TO THE AIR INTAKE (see follow-
ing Figure) PROVIDED ON THE UNIT.