18
OPERATION
POWER VENTED PROPELLER UNITS
INTERMITTENT PILOT IGNITION
EXPLANATION OF CONTROLS (See Figure 10):
1. The unit heater is equipped with a power venter
system consisting 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 on a call for heat. The pressure switch
measures the flow through the vent system and
energizes the indirect ignition system 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 indirect ignition system consists of an ignition
control module, a dual combination gas valve, and a
pilot burner. When the pressure switch closes, the
pilot valves opens and the pilot burner is ignited by
either a spark or hot surface element. When flame
sensing circuit senses that the pilot flame is
established, the main gas valve is opened to supply
gas to the main burners. When the thermostat is
satisfied, the vent system is deenergized and both
valves are closed to stop all flow of gas to the unit.
4. The limit switch interrupts the flow of electric current
to the main gas valve in case the heater becomes
overheated.
5. The fan switch delays the operation of the fan until
the heater is warmed, then keeps the fan running
after the gas has been turned off until the useful heat
has been removed.
The startup fan delay must
not exceed 90 seconds from a cold start.
6. The wall thermostat (supplied optionally) is a
temperature sensitive switch which operates the
vent system and the ignition system to control the
temperature of the space being heated. It must be
mounted on a vibration free, vertical surface away
from air currents, in accordance with the instructions
furnished with the thermostat (also refer to Electrical
Section).
START-UP (Also refer to lighting instruction plate
equipped on the unit)
1. Open the manual valve supplying gas to the unit
heater, and with the union connection loose, purge
air from the gas line. Tighten the union and check
for gas leaks.
Never use an open flame to
detect gas leaks. Explosive conditions may
exist which could result in personal injury or
death.
Before attempting to light or
relight pilot, wait 5 minutes to allow gas which
may have accumulated in the burner compart-
ment to escape.
2. Open the manual valve on the unit heater.
3. Turn ON 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 pilot and main burners ignite. Turn the
thermostat to the lowest point and determine that
the power venter motor shuts off and the pilot and
main burners are extinguished.
5. If pilot adjustment is required, remove the pilot
adjustment seal cap and adjust the pilot screw to
obtain proper flame. Clockwise rotation decreases
pilot flame size. Replace the cap.
6. Turn the thermostat to the desired position.
7. See Gas Input Rate and Adjustments sections.
SHUT DOWN
1. Turn the valve selector knob to the “OFF” position.
2. Turn off the electricity.
3. To relight, follow the “start-up” instructions.
See Figure 10 for parts/identification.
Figure 10
Manifold
Assembly
