15
Servicing should only be performed by a Qualified Service Technician
Blocked Air Intake:
Note these are negative pressures; in a vacuum. If the pressure reading taken at the
Blocked Air Intake Switch sensing tube does not reach or drop lower than the pressure shown in the above
Table
AND
the switch contacts were opening during the "Continuity Test During Operation" shown on Page
13 - the switch is defective and must be replaced. If the pressure reading taken reaches or drops lower
than the pressure shown in the "Pressure Switch Settings" Table on Page 14 and the switch contacts were
opening during the "Continuity Test During Operation" shown on Page 13 - the switch
IS NOT
defective and
should not be replaced. Check for restrictions at the intake air connection on the water heater, check for too
small of pipe installed, too many equivalent feet and/or too many elbows in the intake air piping. Check for
low points in the intake air piping where water may be collecting and blocking the intake air piping. Check for
any restrictions or debris at the intake air termination outdoors. Check for condensate/water in the sensing
tube/switch, if the sensing tube has water in it, replace the Blocked Air Intake Switch and the tube. Ensure
the sensing port is oriented properly, see "Intake Air Connection" on Page 34.
Blocked Exhaust:
If the pressure reading taken at the Blocked Exhaust switch sensing tube does not
reach or rise above the activation pressure given in the above Table
AND
the switch contacts were opening
during the "Continuity Test During Operation" on Page 13 - the switch is defective and must be replaced. If
the pressure reading taken reaches or exceeds the pressure shown in the "Pressure Switch Settings" Table
on Page 14 and the switch contacts were opening during the "Continuity Test During Operation" on Page
13 - the switch
IS NOT
defective and should not be replaced. Ensure the condensate drain connected to the
exhaust elbow on the water heater is not clogged and is draining freely. Check for restrictions or blockage in
the vent pipe, check for too small of pipe installed, too many equivalent feet and/or too many elbows in the
vent piping. Check for low points in the vent pipe where water may be collecting and blocking the vent piping.
Check for any restrictions or debris at the vent termination outdoors.
