Aerovent IM-500 - Manual (Page 16)

16 Aerovent IM-500
Remote Switch in “Summer” Position
With the remote switch in the “Summer” position, the fol-
lowing sequence of operation will occur.
1. Inlet and/or discharge damper is energized.
2. When damper is 65% open, the internal damper motor
end switch will make and allow power to be supplied to
the motor or motor starter. Fan will start and supply air
to the distribution system. The blower light will come
on.
3. The gas controls and temperature controls are locked
out to prevent heating during the “Summer” mode.
Note: The burner will not come on with the switch in
“Summer”. The fan will continue to run as the temperature
drops.
Remote Switch in “Winter” Position
If freeze protection is furnished with the unit, the freeze
protection timer will be energized at this time to provide
power to the inlet and/or discharge damper.
With the remote switch in the “Winter” position, the
above sequence continues:
4. The running interlocks supply power to the flame relay
through contacts on high temperature limit control and
high and low gas pressure switches, mild weather tem-
perature stat, proof of airflow switch, proof of closure
switch and freeze protection sensor.
5. After 7 seconds of pre-purge time, the flame safeguard
ignition sequence is energized, the ignition transformer
is energized and pilot valve is opened.
6. After pilot is lit and proven, the main gas valves are ener-
gized and the burner fires at low fire. The burner “On”
light is energized on the remote panel when the main
valves are completely open and the end switch is made.
7. Burner remains on low fire until the main valves are
100% open and the end switch is made. The tempera-
ture controls then take over and modulate burner firing
based on load demands.
NOTE: If the unit has been supplied with a dirty filter
switch, the filter light will come on if the pressure drop
across the filters becomes excessive.
If a flame failure should occur (lock out time: 17 sec-
onds) the burner light on the remote panel will go out. The
flame safeguard relay will go into lockout. The unit selector
switch must be turned off before the unit can be restarted
again. The flame safeguard reset button (optionally located
on the remote station) must be manually reset in order to
restart the burner. If you have a remote reset, travel to the
unit is not required.
CAUTION:
After resetting the reset button on the flame safeguard
relay three times and the unit fails to light off, have service
department check unit to determine cause of failure.
Using the Circuit Analyzer to
Isolate Defective Components
Troubleshooting the Aerovent air make-up control systems
has been simplified by the use of the circuit analyzer. The
light numbers are the same as the wire numbers for each
circuit. They are also arranged to operate in sequence. The
analyzer is turned on by the toggle switch. If any circuit is
not energized, the sequence will stop at that point until the
fan shuts down (approximately 90 seconds). It should be
emphasized that the circuit analyzer will show the location
of a malfunction only during the starting cycle. To start
a new cycle, turn the unit off, wait 30 seconds, and then
turn it on again. Observations are made with the discon-
nect switch closed and the selector switch in the “Winter”
position.
If lamp #3 does not light, check:
1. Is lamp #3 getting power or is the bulb defective?
2. The fuse (Buss FNM 5 amp).
3. Line voltage on the primary side of control transformer.
4. Control voltage on secondary side of control trans-
former.
5. Jumper between H and 1 on the terminal strip.
6. Continuity between 1 and 3 on the selector switch.
If lamp #4 does not light, check:
NOTE: May not come on until flame is established.
1. Is lamp #4 getting power or is the bulb defective?
2. Contacts and operation of low temperature limit ther-
mostat (Dial setting 30 o ). Temp. below setpoint.
If lamp #5 does not light, check:
1. Is lamp #5 getting power or is the bulb defective?
2. Contacts and operation of reset timer.
If lamp #6 does not light, check:
1. Is lamp #6 getting power or is the bulb defective?
2. Operation of shutter motor.
If lamp #7 does not light, check:
1. Is lamp #7 getting power or is the bulb defective?
2. Contacts and setting of mild weather thermostat.
3. Ambient temp above MW setting.
If lamp #8 does not light, check:
1. Is lamp #8 getting power or is the bulb defective?
2. Selector in “summer” position.
3. Continuity between 7 and 8 on the selector switch.
If lamp #9 does not light, check:
1. Is lamp #9 getting power or is the bulb defective?
2. Line gas pressure.
3. Low gas pressure switch. (Manual reset)
If lamp #10 does not light, check:
1. Is lamp #10 getting power or is the bulb defective?
2. High gas pressure switch. (Manual reset)