Aerovent IM-200 - Manual (Page 3)

IM-200 3
overhead door. Normal operation is to leave the on-off switch
“on” and cycle the unit with the door switch as the overhead
door on the dock opens and closes.
Door opening closes the switch between terminal #1 and
#3; the fan starts. Interlock (E) on the fan starter (FSR) closes
the circuit between terminal #6 and #7. An electrical circuit is
made to terminal #7 through the high gas pressure switch (C)
and airflow switch (D). Power on terminal #7 will cause the
primary combustion relay (RM7890) to pull in. Ignition occurs
powered from terminal #9, main gas valves open powered
from terminal #11.
Flame is proven through the flame rod and the RM7890
primary relay allows power to energize terminal #10 and de-
energizes terminal #9 dropping out the ignition transformer.
If discharge temperature exceeds 200°F, high limit (A)
between terminals #10 and #11 will open which de-energizes
the gas valves. Loss of flame will cause combustion relay to
lock out requiring manual reset on IRI, FM single valve and
1. Switch the on-off toggle switch to the “ON” position in
remote station. The indicator light should come on. If not,
check the power supply to the unit, the fuse between H and
XI or the bulb to see if it has burned out.
2. Close the door switch between terminal #1 and #3. The
fan should start. If not, check overload on the motor
starter (manual reset) when the fan starts auxiliary contact
between terminal #6 and #7 closes. You should have 120
volts to terminal #7 (flame relay). If not, check the high gas
pressure switch (manual reset) or the airflow switch. The
high gas pressure switch should be set at 21.0". The airflow
switch should be set at 1.0".
3. When the flame relay has power to terminal #6, it will go
through a self-checking cycle and then power wire #9 from
terminal #10, turning on the ignition transformer and wire
#10 from terminal #8, opening the main valves. If ignition
(spark) is occurring but valves do not open, check the high
limit between terminal #10 and #11. High limit should be
set at 200°F. If spark is not occurring, check the spark plug.
The gap should be 0.072 and the electrode should be clean
(no carbon). If the flame relay has power to it but flame
cycle will not occur, reset the flame relay (manual reset). If
flame comes on momentarily and goes out, check the flame
rod. There should not be any cracks in the porcelain. The
flame rod senses current in the flame. To check if it is
functioning, plug a voltmeter into the amplified module.
The unit should be 0-5 volts D.C. (On older units equipped
with RA890F, a test jack is beside the red reset button and
the unit should be minimum 2 microamps. Normal range
is 2-5 microamps.)
4. IRI and FM units work the same as standard with the
exception that they have a pilot which lights before the
main flame comes on. If the pilot does not light, check to
see that the 1 ∕
4
" pilot valve is opening, the pilot gas line is
not obstructed or the pilot assembly in the burner is intact.
Also, there is a timer to turn the pilot off after the burner
lights which should be set at approximate 5 seconds. Check
the timer to make sure it is functioning.
5. Some units are supplied with a UV scanner (mini-peeper)
rather than a flame rod. Flame current check should yield
the same results as a flame rod: 0-5 volts D.C. (on older
units equipped with RA890G flame relay, flame current
should be minimum 1.5 microamps).
For additional troubleshooting guidance, refer to
RM7890A1015 bulletin.
FM 2 valve. The standard unit will try to restart on flame loss.
The sequence of operation is similar for IRI and FM units.
For schematic wiring, see the following reduction drawings:
Standard . . . . . . . . . . . . . . . . . R26871-00
IRI . . . . . . . . . . . . . . . . . . . . . R26870-00
FM Single Valve. . . . . . . . . . . R26870-00
FM Two Valve . . . . . . . . . . . . R26869-00
All Piping Diagrams . . . . . . . R26872-00
Standard Wiring and Piping Sequence of Operation
Troubleshooting