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About Advanced Features & Operation
SINGLE SETPOINT BEHAVIOR - When configured
for Single Setpoint operation (step #2, page 10), the
degree icon will blink when the large number is display-
ing room temperature and will remain solid when dis-
playing the heating or cooling setpoint. In the Auto
mode the deadband is enforced both above and below
the setpoint. To avoid short cycling, a deadband of at
least two degrees is recommended (step #6, page 12).
To display the room temperature press and hold the
MODE button for two seconds. Release the MODE
button to return to the normal display.
Auxiliary Input Control and Multiple HVAC Control
Potential Phasing Problems
CAUTION
When using the auxiliary input (CK1 & R) or controlling multiple HVAC units with a
single thermostat, it is possible to encounter transformer phasing problems that will
interfere with thermostat operation. Connecting transformers that are not phased
correctly may result in a direct short, which could damage transformers and/or the
thermostat. Phasing problems are likely if the units share a common ground with
secondary grounded transformers.
SOLUTION: If possible, phase all HVAC units together. If phasing is impractical,
isolation relays may be used to isolate the transformers. To isolate the auxiliary
input, use a separate transformer for the auxiliary control device, usually a time clock.
Connect the device to an isolation relay coil. Connect one set of isolated contacts to
each thermostat at CK1 and R. See diagram A.
Diagram A- Auxiliary Control
110vac
Additional relays may be used. Relay coils must be wired in parallel.
Isolation Relay
Coil
Page 24
WARNING
CK 1
Thermostat
R
CK 1
Thermostat
R
CK 1
Thermostat
R
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