York E1FB240, E1FB180 OPERATION BELOW 0F OUTDOOR TEMPERA TURE, Emergency Heat Operation

035-16192-001-A-1001

OPERATION BELOW 0°F OUTDOOR TEMPERA-

TURE

1.At 0°F outdoor temperature, the low temperature compres- sor cutoff thermostat TH1 and TH3 contacts 1 and 3 will open, de-energizing contactor 1M and 3M which shuts down the compressor. Contacts 1 and 2 of thermostat TH1 and TH3 are closed when contacts 1 and 3 are open. This feature allows the standby electric heat (if installed) to oper- ate under control of first stage heating TH1 of the room ther- mostat whenever the compressor is shut-down by the 1TH control. The standby electric heat will continue to be con- trolled by the second stage TH2 of the room thermostat same as described under Item 8 of HEATING OPERA- TION.

2.The indoor section blower operation will be controlled by the first stage heating TH1 of the room thermostat if the fan switch is in the “AUTO” position.

EMERGENCY HEAT OPERATION

When the system switch on the room thermostat is placed in the EMERGENCY HEAT position, operation is as follows:

1.The emergency heat light on the room thermostat will be energized.

2.Compressors will not operate because the Y circuit of the room thermostat cannot be energized.

3.Standby electric heat (if installed) will be controlled by first stage heating TH1 of room thermostat.

4.Indoor section blower will also be controlled by first stage heating TH1 if fan switch is in the “AUTO” position.

Unitary Products Group 13