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Is there continuity
through the normally
closed intake pressure
switch?
(see photo at right)
Y
Replace
intake pressure switch.
(see “Intake Pressure Switch
Replacement Procedure”)
Switch OK.
Does Blower Energize?
Does purge LED
illuminate on the ignition
module?
Remove hose from intake
pressure switch and
Restart heater.
Does purge LED illuminate?
N
Y
With manometer, take a
reading from the inlet tube
pressure tap. Is reading
negative (-)1.2" W.C.
or more?
(see illustration below)
N
See “Vent Safety Switch Testing
and Replacement”
or
Exhaust Pressure Switch Tesinting
and Replacement”
or
“Blower Testing and Replacement”
Y
N
Y
N
N
Y
Is intake vent system
obstructed?
Y
N
Call for technical support.
Clear obstruction.
See “Exhaust Pressure Switch Testing
and Replacement”)
or
“Blower Testing and Replacement”
Used on EF water heaters prior to “CF” serial number.
Is there continuity
through the normally
closed intake pressure
switch?
(see photo above)
Y
Isolate (disconnect) heater from
intake vent system and
Restart heater.
Does purge LED illuminate?
N
Y
N
Disconnect red wire leads from
pressure switch and check
continuity through switch.
WARNING
120 volt potential exposure. Use caution
making voltage checks to avoid personal injury.
Notice:
The intake pressure switch is not used
on serial number “CF” and later.
Inlet Tube
pressure tap
69
69