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20
OPERATION
POWER VENTED PROPELLER UNITS
DIRECT SPARK IGNITION
EXPLANATION OF CONTROLS (See Figure 20):
1. Each Unit Heater comes equipped with a power vent
system that consists of a power venter motor and
blower, pressure switch, and sealed flue collector in
place of the conventional draft diverter.
2. The power venter motor is energized by the room
thermostat through the integrated control board when
a demand for heat is sensed. The pressure switch
measures the flow through the vent system and
energizes the direct spark ignition system beginning
the pre-purge timing when the flow is correct.
The pressure switch MUST NOT
be bypassed. The unit MUST NOT be fired unless
the power venter is operating. An unsafe
condition could result.
3. The direct ignition system consists of an ignition
control module and a gas valve. When the pre-purge
period ends, the spark ignition system is energized,
and the gas valve opens to supply gas to the burners.
When the thermostat is satisfied, the vent system is
de-energized and the valve closes to stop the flow of
gas to the unit.
4. The limit switch interrupts the flow of electric current
to the control board, interrupting the flow of gas to the
gas valve if the unit heater becomes overheated.
5. The flame roll-out switch interrupts the flow of electric
current to the control board, interrupting the flow of
gas to the unit heater in the event of sustained flame
roll-out from the burner area. If this switch trips,
DETERMINE AND CORRECT THE CAUSE of the
flame roll-out.
6. Once the thermostat is satisfied, or the limit switch
interrupts the flow of electric current to the control
board, the unit will begin a post-purge period. When
the post-purge period ends, the power venter motor is
de-energized.
7. The fan operation is delayed 30
seconds once the thermostat is
closed, and continues operation
for 30 seconds after the thermostat
opens.The start-up fan delay
must not exceed 30 seconds
from a cold start.
8. The wall thermostat, supplied optionally, is a
temperature sensitive switch that operates the
vent system and ignition system to control the
temperature of the space being heated. The thermo-
stat must be mounted on a vertical, vibration-free
surface free from air currents and in accordance with
the furnished instructions (also refer to Electrical
Section).
START-UP (Also refer to lighting instruction plate
equipped on the unit)
1. Open the manual gas valve in the gas supply line to
the unit heater with union connection loose, purge
air from the gas line. Tighten the union and check for
leaks.
Never use an open flame to detect
gas leaks. Explosive conditions may exist wich
could result in personal injury or death.
2. Open the manual valve on the unit heater.
3. Turn ON the electrical power.
4. The unit should be under the control of the
thermostat. Turn the thermostat to the highest point
and determine that the power venter motor starts and
the burners ignite. Turn the thermostat to the lowest
point and determine that the power venter motor
shuts off and the burners are extinguished.
5. Turn the thermostat to the desired position.
6. See Gas Input Rate and Adjustments sections.
SHUT DOWN
1. Turn the valve selector lever to the “OFF” position.
2. Turn off the electricity.
3. To relight, follow “start-up” instructions.
See Figure 20 for parts/identification.
Figure 20