Owner`s manual

PLC Control Startup
21
Gas Pressure Adjustments
PRIMARY AIR ADJUSTMENT
NOTE: Gas models only.
The air shutter disc on the burner blower motor, lo-
cated inside the control box on top of the burner,
is factory adjusted t o provide the most efficient
blue flame possible a t sea level.
1. Visually examine the quality of the flame.
2. If it needs adjusting, increase or decrease the
air mixture to attain the best flame quality. Be
sure to tighten the lock nut when finished.
NOTE: If there is no sight glass in the end of
the burner, open the front access door
completely. Look beneath the nozzles
to view the flame quality.
3. Ifthecombustionbloweralarmisactuated,
the combustion pressure switch may need to
be readjusted. The adjustment screw is visible
on the top of the pressure switch.
NOTE: The pressure switch is located on the
ignition control board. See Figure 16,
view D for a detail of the pressure
switch.
COMBUSTION BLOWER PRESSURE SWITCH
ADJUSTMENT
The adjustment o f the pressure switches after
insta l lation is extremely important. The switch
proves that the gas combustion air blower is op-
erational. If the pressure sw itch stays open, the
ovenwillnotheat. Theoperatorwillbegivenboth
audible and visual alarms for a combustion blower
failure: “COMBUSTION BLWR F AIL”
If the sw itch is adjusted too sensitively (“---“ clock-
wise), it will not open w hen the combustion blower
is turned off. In this case, when the oven is turned
on again, the control system would see the pres-
sure switch as “stuck closed.” The oven will not
heat, and the operator will be given both audible
and visual alarms indicating combustion pressure
switch failure: “COMB PS FAILURE.”
ADJUSTMENT
1. With the oven OFF and the combustion blower
OFF (it’ll shut off 20 seconds after t urning the
oven off), turn the adjustment screw clock-
wise (---) just until the pressure switch closes
(indicated when the LED marked “COMB PS”
is illuminated on the control tray).
2. Slo wly turn the adjustment screw counter---
clockwise approximately (+) 1/4 turn PAST the
point where the switch o pens (L ED shuts of f).
3. Turn t he oven ON.
4. Place your hand over the circular air shutter on
the combustion blower. Close off part of the air
opening with your hand and fingers.
NOTE: Adjust the switch to close only when
the combustion fan is operating either
with very
little or no restriction
5. If the switch is adjusted properly, an audible
alarm sounds and a fault appears in the dis-
play indicating a combustion blower failure:
“COMBUSTION BLWR FAIL.” If so, no furth e r
adjustment is necessary. If there is no alarm,
the pressure switch needs a djustment as fol-
lows:
6. Turn the adjustment screw counter---clo ckwise
(+) another 1/4 turn and test again if it will close
easil y by bloc king it with your hand. This all ows
the pressure switch to open more easily.