Replacing the Air Flow DifferentialPressure Switch
If the air flow differential pressure switch fails to detect the pressure drop between
the heater inlet and outlet, it should be replaced.
1Stop the heater, disconnect and lockout the main power.
2Gain access to the heating elementsby removing screws that
secure the heating element cover to the enclosure.
3Remove the heating element cover by tilting
the top away from the enclosure slightly,then
lifting the cover up and away from the enclo-
sure.
4Note their location then remove the two
wires connected to the pressure switch.
5Note their locations then disconnect the
hose coming from the heater outlet from
the low pressure side of the switch and the
hose coming from the heater inlet from
the high pressure side of the switch.
6-14 l Troubleshooting
ON
O OFF
IMPORTANT:Always refer
to the wiring diagrams
that came with your
heater to locate specific
electrical components.
Illustrations in the User
Guide are intended to be
representative only.