Service manual

8
The thermostat operation switches the
12VDC + to all output terminals.
6535-3351 Heat Pump Thermostat Example To Bring On Gas Furnace as 2
nd
Stage Heat
Setpoint Indoor Temp. Operation
70 70+ No functions occur
\\\ 69 Heat Pump turns on (Primary heat source)
71 Heat Pump turns off (Thermostat satisfied)
69 Heat Pump turns on
65 Gas Furnace turns on (Heat Pump not able to satisfy Thermostat)
(First strike for 2
nd
stage heat counter)
71 Heat Pump and Gas Furnace turn off (Thermostat satisfied)
69 Heat Pump turns on
65 Gas Furnace turns on (Heat Pump is again unable to satisfy
Thermostat), (2
nd
stage heat counter reaches 3
rd
strike and Heat Pump is
locked out for 2 hours), 2
nd
stage heat counter is reset if Heat Pump is
running for more than 20 minutes and does not call for 2
nd
stage heat
71 Gas Furnace turn off (Thermostat satisfied)
69 Gas Furnace turns on (Becomes Primary heat source)
71 Gas Furnace turns off (Thermostat Satisfied)
\\\ After 2 hour lockout
69 Heat Pump turns on (Resumes as Primary heat source)
65 Gas Furnace turns on (Becomes primary heat source)
(Heat Pump is locked out for another 2 hours)
71 Gas Furnace turns off (Thermostat Satisfied)
\\\ After 2 hour lockout
69 Heat Pump turns on (Resumes as primary heat source)
71 Heat Pump turns off (Thermostat satisfied)
(2
nd
stage heat counter is reset any time Heat Pump satisfies
thermostat setpoint and does not need Gas Furnace)
The word “DIFF” will flash on LCD when 2
nd
stage heat is operating.
There is a 30 second delay between Stage 1 and Stage 2. Heat pump operation.
There is also a 3 minute anti-short cycle delay time of 3 minutes for cooling.
6535-3351 Thermostat Wiring