Instruction manual

Connect an accessory 24 VAC, 0.5 amp. maximum humidifier (if

used) to the ¼--in. male quick--connect HUM terminal and

COM--24V screw terminal on the control board thermostat strip.

NOTE: If the humidifier has its own 24 VAC power supply, an

isolation relay may be required. Connect the 24 VAC coil of the

isolation relay to the HUM and COM/24V screw terminal on the

control board thermostat strip. (See Fig. 33.)

3. Communication Connector (ABCD connection)

This connection is used when the furnace is controlled by

an optional communicating User Interface instead of a

standard thermostat. The ABCD plug is supplied with the

User Interface. Refer to the instructions supplied with the

User Interface for complete details. See Fig. 35.

4. Outside Air Thermistor (OAT)

The OAT connection is used in conjunction with commu-

nicating User Interface. It is not required when the furnace

is controlled by a standard type thermostat. Refer to the in-

structions supplied with the User Interface for complete de-

tails.

Alternate Power Supplies

This furnace is designed to operate on utility generated power

which has a smooth sinusoidal waveform. If the furnace is to be

operated on a generator or other alternate power supply, the

alternate power supply must produce a smooth sinusoidal

waveform for compatibility with the furnace electronics. The

alternate power supply must generate the same voltage, phase, and

frequency (Hz) as shown in Table 9 or the furnace rating plate.

Power from an alternate power supply that is non-sinusoidal may

damage the furnace electronics or cause erratic operation.

Contact the alternate power supply manufacturer for specifications

and details.

986TA