About Advanced Features & Operation
SINGLE SETPOINT BEHAVIOR - When configured
for
Single Setpoint
operation
(step #4, page 19)
,
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 and
Program On modes the deadband is enforced both
above and below the setpoint. To avoid short cycling,
a deadband of at least two degrees is recommended
(step #8, page 20)
. To display the room temperature
press and hold the MODE button for two seconds.
Release the MODE button to return to the normal
display.
Page 32
Auxiliary Input Control and Multiple HVAC Control
Potential Phasing Problems
110vac
Isolation Relay
Coil
CK 1
R
Thermostat
CK 1
R
Thermostat
CK 1
R
Thermostat
Additional relays may be used. Relay coils must be wired in parallel.
Diagram A- Auxiliary Control
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.
CAUTION
WARNING
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.