Goodman Amana ComfortNet GMVC8 Service Instructions Manual page 33

PRODUCT DESIGN
Single-Stage Thermostat Application
A single-stage thermostat with only one heating stage may
be used to control this furnace. The application of a single-
stage thermostat does not offer "true" thermostat-driven two-
stage operation, but provides a timed transition from low to
high fire. The furnace will run on low stage for a fixed period
of time before stepping up to high stage to satisfy the
thermostat's call for heat. The delay period prior to step-
ping up can be set at either a fixed 5 minute time delay or a
load based variable time between 1 and 12 minutes (AUTO
mode). If the AUTOmode is selected, the control averages
the cycle times of the previous three cycles and uses the
average to determine the time to transition from low stage to
high stage.
To use a single-stage thermostat, turn off power to the fur-
nace, move the thermostat selection DIP switch to the OFF
position. Set the desired transition time by setting the tran-
sition delay DIP switch to the desired ON/OFF position.
Turn power back on. Refer to the following figure.
OFF
Heat OFF Delay
DIP Switches
3
4
S1
PCBKF103 / PCBKF104 / PCBKF105
ON
Move to the ON position
to select two-stage
thermostat or OFF to
select single stage
thermostat
Thermostat
Stage Delay
Move to the ON position
to select Auto transition
delay or OFF for 5 minute
transition delay
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