Raypak 503-2003 - Manual (Page 42)

42
Air Pressure Switch
This heater is equipped with an air pressure switch to
prove the operation of the blower before allowing the
ignition control to begin a Call for Heat. It is located on
the right side of the lower flange of the blower mount-
ing assembly, directly behind the junction box.
Blocked Vent Switch
This heater is equipped with a blocked vent pressure
switch to prevent the operation of the heater when too
much of the vent is blocked. This switch is located on
the right side of the heater near the right rear corner.
UDB Diagnostic Board
This heater is equipped with a diagnostic board which
will indicate faults as they occur. It has the ability to
retain up to 256 faults in history. Refer to the Trouble-
shooting section for instructions on accessing,
reviewing and clearing these faults.
Fig. 42: Air Pressure Switch
Fig. 43: Blocked Vent Switch
SW1
SW2
Fig. 44: UDB Diagnostic Board