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WIRING – LOW VOLTAGE WIRING
Low Voltage Connection
These units use a 24-volt AC low voltage circuit.
Tables 11 – 13 on pages 23 – 25 show the low voltage
connections for units operated with the MV Series
controller, MC Series controller or connected directly to
a cooling/heating thermostat.
All models are equipped with dual primary voltage
transformers. All equipment leaves the factory wired
on 240V tap. For 208V operation, reconnect from
240V to 208V tap. The acceptable operating voltage
range for the 240 and 208V taps are:
TAP
240
208
NOTE: The voltage should be measured at the field
power connection point in the unit and while
the unit is operating at full load (maximum
amperage operating condition).
DIRTY FILTER SWITCH AND RELAY
These units include an adjustable dirty filter indicator
switch. This switch if connected to normally closed
contacts on the filter relay wired to terminals 10 and
11 on the low voltage terminal block.
Filter Replacement Procedure
For units not equipped with economizer:
1. Turn off unit power.
2. Remove filter door.
3. Replace filter.
4. Press Reset button.
5. Verify filter light is off.
6. Replace filter door.
7. Turn on unit power.
For units equipped with economizer:
1. Turn off unit power.
2. Remove hood cover.
3. Remove mist eliminator. Inspect and clean if
necessary.
4. Remove filter door.
5. Remove and replace filter.
6. Replace filter door.
7. Replace mist eliminator.
8. Replace hood cover.
9. Turn on unit power.
Manual 2100-639A
Page
14 of 28
RANGE
253 – 216
220 – 187
Filter Switch Adjustment
1. Turn off unit power.
2. Remove upper front door. Front screws on unit top
can be removed for ease of removing upper front
door.
3. Locate filter switch on control panel side next to
blower assembly.
4. Remove single phillips head screw on front of
cover. Remove cover.
5. Set pressure by adjusting knob. Do not adjust
knob drastically to avoid nuisance alarm signalw
or non-functionality.
6. Replace cover.
7. Replace upper front door.
8. Turn on unit power.
ECONOMIZER FAIL TIME DELAY RELAY
NOTE: Applies only to units with economizers.
These units employ a time delay relay to open the
nomally closed contacts at terminals 12 and 13 on the
low voltage terminal block. This will activate an alarm
signal on the MV Series controller. The time delay is set
to 500 seconds as a factory default. Avoid adjustment
to settings lower than 180 seconds.
Timer to be set here
(500 seconds)
MIS-3054
MIS-3054
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