Operation & Installation Manual 09/2002

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A00279

Fig. 50E—Dual Fuel Thermostat with Two-Stage

Furnace and Single-Speed Heat Pump

A00281

Fig. 50G—Two-Stage Thermostat With Two-Stage

Furnace and Two-Speed Air Conditioner

A00282

Fig. 50H—Single-Stage Thermostat With Two-Stage

Furnace and Two-Speed Air Conditioner

A00280

Fig. 50F—Dual Fuel Thermostat With Two-Stage

Furnace and Two-Speed Heat Pump

b. When the R to G-and Y/Y2 circuit is closed and there is a demand for dehumidification, the furnace blower motor

BLWM will drop the blower speed from COOL to HI

HEAT for a maximum of 10 minutes before reverting back to COOL speed. If there is still a demand for dehumidification after 20 minutes, the furnace control CPU will drop the blower speed back to HI HEAT speed. This alternating

10-minute cycle will continue as long as there is a call for cooling.

c. When the ″call for cooling″ is satisfied and there is a demand for dehumidification, the cooling blower-off delay is decreased from 90 seconds to 5 seconds.

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CONTINUOUS BLOWER MODE

When the R to G circuit is closed by the thermostat, the blower motor BLWM will operate on continuous-blower speed (can be set to LO HEAT, HI HEAT, or COOL speed). Factory default is LO

HEAT speed. Terminal EAC-1 is energized as long as the blower motor BLWM is energized.

During a call for heat, the blower BLWM will stop during igniter warm-up (17 seconds), ignition (7 seconds), and blower-ON delay

(66 seconds), allowing the furnace heat exchangers to heat up more quickly, then restarts at the end of the blower-ON delay period at

LO HEAT or HI HEAT speed respectively.

In high-heat, the furnace control CPU will hold the blower motor