Venstar T1075 - Manual (Page 38)

Auxiliary Input Control and Multiple HVAC Control
Potential Phasing Problems
Important Information About:
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
transformer phasing problems that will
operation. Connecting transformers that are not phased
correctly may result in a direct short, which could damage the
transformers and/or the
if the units share a common ground with
single thermostat, it is possible to encounter
interfere with thermostat
thermostats. Phasing problems are likely
secondary grounded
transformers.
CAUTION WARNING
SOLUTION: If possible, phase all HVAC units together.
If phasing is impractical,
the transformers. To isolate the auxiliary
transformer for the auxiliary control device, usually a time clock.
Connect the device to an isolation relay coil. Connect one set
each thermostat at CK1 and R.
See diagram A.
isolation relays may be used to isolate
input, use a separate
of isolated contacts to
Page 37
Sample Time Clock Wiring Diagram