507276-03 Page 43 of 59Issue 1621
Install the room thermostat according to the instructions
provided with the thermostat. See Figure 63 for thermostat
designations. If the furnace is being matched with a
heat pump, refer to the FM21 installation instruction or
appropriate dual fuel thermostat instructions.
Indoor Blower Speeds
1. When the thermostat is set to “FAN ON”, the indoor
blower will run continuously on the fan speed when
there is no cooling or heating demand.
2. When the furnace is running in the heating mode, the
indoor blower will run on the heating speed.
3. When there is a cooling demand, the indoor blower will
run on the cooling speed.
Generator Use - Voltage Requirements
• The furnace requires 120 volts ± 10% (Range: 108 volts
to 132 volts)
• The furnace operates at 60 Hz ± 5% (Range: 57 Hz to
63 Hz)
• The furnace integrated control requires both proper
polarity and proper ground. Both polarity and proper
grounding should be checked before attempting to
operate the furnace on either permanent or temporary
power.
• Generator should have a wave form distortion of less
than 5% THD (total harmonic distortion).
terminals. If a humidier rated at greater than one amp
is connected to this terminal, it is necessary to use an
external relay. See Figure 66 for control board conguration.
This terminal is energized in the heating mode when the
combustion air inducer is operating.
One 24V “H” 1/4” spade terminal is provided on the furnace
control board. Any humidier rated up to 0.5 amp can be
connected to this terminal with the ground leg of the circuit
connected to ground or the “C” terminal. See Figure 66 for
control board conguration. This terminal is energized in the
heating mode when the combustion air inducer is operating.
Figure 63
Figure 64
Typical Field Wiring Diagram