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ADJUSTMENTS
P
RESSURE
S
WITCH
A
DJUSTMENTS
With the venter air flow set and the appliance operating at the best operating
efficiency, adjust the pressure switch by rotating the adjustment screw
clockwise until the burner shuts off, then rotate the adjustment screw
counterclockwise until the burner fires. Rotate the adjustment screw an
additional 1/4 turn counterclockwise to ensure proper switch setting. (See
Figure 6)
P
OST
P
URGE
T
IMING
A
DJUSTMENT
To adjust the post purge time, rotate the timer adjustment on the timer
clockwise to increase the operation time. To decrease the operation time,
rotate the timer adjustment counterclockwise. (See Figure 7) Typical post
purge time should be between 3 to 5 min.
S
YSTEM
C
ONTROL
C
HECK
O
UT
P
ROCEDURES
1. Adjust the thermostat to call for heat and observe the power venting
system for proper
sequence of operation:
(Repeat if necessary)
.
1.
Thermostat calls for heat.
2.
Relay is energized, post purge timer is energized, and venter
motor starts.
3.
Pressure switch closes and burner starts.
4.
Thermostat is satisfied, relay is de-energized, burner stops and post purge timer operates venter
motor for approximately 3 to 5 minutes.
2. While system is operating, disconnect power to the venter motor. This should open the pressure switch
contacts and stop burner operation.
3. (If WMO-1 switch is installed) Allow vent system to cool. Disconnect the vent pipe between the venter inlet
and the appliance outlet. Block the vent pipe with a noncombustible material. Activate the heating system
with the main burner operating. Allow approximately 2 minutes or less for the secondary safety switch to
deactivate the burner. Reset safety switch and repeat.
MAINTENANCE
1. Motor: Inspect motor once a year; the motor should rotate freely.
2. Wheel: Inspect venter wheel annually, for oil fired heating systems, clear any soot, ash or coating which
inhibits either rotation or air flow. Remove all foreign material before operating.
3. Vent System: Inspect all vent pipe connections annually for looseness and for evidence of flue gas
leakage. Seal or tighten pipe connections if necessary.
TROUBLE SHOOTING HINTS
1. Main burner does not fire when thermostat calls for heat with venter operating.
a. Check pressure switch adjustment.
b. Check fuel flow.
c. Check wiring connections between pressure switch and burner.
d. Check pressure switch for continuity across terminals, during venter operation.
2. Venter does not activate when thermostat calls for heat.
a. Jump wire the terminals L1 and M to ensure motor operation.
b. Check wiring.
3. Flue gas odor.
a. Check system draft.
b. Check post purge venting time.
c. Check for negative pressure in building.
Figure 7
Figure 6
