VHX SERIES STEAMER - SERVICE PROCEDURES AND ADJUSTMENTS
F24700 (October 2001)Page 33 of 68
AIR PRESSURE SWITCH
ADJUSTMENT
The air pressure switch senses the pressure level
produced by the blower for combustion. W hen the
pressure is sufficient, the switch cl oses and supplies
power to the ignition control modul e. The gas
ignition sequence starts to light the gas pi l ot and
then main burner. If the gas pil ot is not lighting
(valve not energiz ed) , the ignition control modul e
may not be receiving power, assumi ng the minimum
water level is satisfied. Chec k the air pressure
switch operation then adjust if necessary as outli ned
in the procedure below.
1. Turn the power switch OFF.
2. Remov e t he left side panel from t he c abinet
base.
A. Inspect the air intake to the blower f or
debris build up and clogging.
1) If debris is found, c l ean it away from
the air intake.
B. Turn the power switch ON and verify m ain
burner ignition.
1) If burner ignites then no adj ustment to
the pressure switch setting is
necessary.
2) If burner does not ignite, proceed to
step 3.
3. Open the cabinet base door and t ur n t he
ON/OFF knob for the mai n gas valve to OFF.
4. Adjust the air pr essure switch sett i ng as
follows:
A. Turn the adjustment screw fully c l ockwise
to the highest setting.
B. Slowly turn the adjustment screw
counterclockwise until the pil ot gas valve
energizes then add ½ turn to the
adjustment.
NOTE: The screw head should not extend out
past the screw housing.
1) If Pilot gas v alve energizes, proceed
to step 5.
2) If Pilot gas v alve does not energize,
check the following:
a. Remov e t he lead wires from the
switch and verify with a met er
that the switch contacts are
closing with the blower ON. If
necessary, continue to turn the
adjustment screw several turns
counterclockwise to CLOSE the
switch contacts.
b. If the switch c ont acts are not
closing, turn the power switch
OFF, remove the pressure
switch from the TEE and check
the air orifice for debr i s build up
and clogging. If debris is found,
clean it away from the orif ice.