Wiring Diagrams - Crestron CHV-THSTAT Operation And Installation Manual

Thermostats

Wiring Diagrams

12 • Thermostats: CHV-TSTAT and CHV-THSTAT
Crestron CHV-TSTAT and CHV-THSTAT
The wiring diagrams that follow show connections for the CHV-TSTAT and CHV-
THSTAT. The heating or cooling system can supply power to the thermostat, or a
separate transformer can supply it. In many installations, spare conductors are
available to supply 24 VAC to the thermostat, using the C (24 VAC common)
connection on the HVAC equipment.
The P4 jumper internally connects either the RH (Reference Heat system) or RC
(Reference Cooling system), relieving the installer from connecting a jumper from
the 24(R) terminal to the RH or RC terminal.
If power is available from the HVAC system, follow the diagrams for the proper P4
jumper connection.
When power is not available from the HVAC system, a separate transformer,
connected between 24(R) and 24(C) terminals, can provide power to the thermostat.
When powered by a separate transformer, ensure that the P4 jumper is connected
across pins 2 and 3 (No Connection) to prevent damage to the thermostat and the
HVAC system.
CAUTION: The P4 Jumper Position on the Circuit Board is critical to proper
operation. Improper P4 jumper position can cause equipment damage. The P4
jumper connects the 24(R) terminal to the RH, or RC connector. Refer to the
following illustration.
P4
Connects 24(R) to RH
1
2
No Connection
3
4
Connects 24(R) to RC
NOTE: Ensure that the power circuits are shut off at the source before connecting
the thermostat. Provide disconnect means and overload protection as required for the
power supply.
NOTE: Ensure that the transformer has sufficient power for all the thermostats in
the system, or use multiple transformers. Refer to the power requirements in
"Specifications" on page 3.
The following diagrams are examples of connections for heat, heat/cool and one-
stage and two-stage heat pump systems, and various slab systems.
NOTE: Use either connector O or B as required, for changeover control.
Operations and Installation Guide – DOC. 8163C