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Section 3. Installing the 4500 Thermostat
3-3
Sometimes, R and Rc are jumpered together at the premises thermostat and
are connected to the HVAC system with a single common wire. This is the
case if both heating and air conditioning are controlled by the same control
system.
The remaining three wires connect the thermostat to the heating, cooling and
fan control loop inputs of the HVAC system.
Under the correct circumstances, switches in the thermostat connect the
applicable power connection (R or Rc) to the applicable control loop of the
HVAC system, turning it on. For example, if the thermostat is set to turn the
heat on when 65 degrees is reached, the relay contacts between the power
connection (R) and the wire going to the heating control loop (W) will close
when the temperature drops to 65 degrees. The heating system will be
activated. Figure 3 shows the same system with the 4500 thermostat and
4286 phone module added:
R
HVAC
System
Rc
Heat (W)
Cool (Y)
Fan (G)
RRc
Heat (W)
Cool (Y)
Fan (G)
PREMISES
THERMOSTAT
4286
PHONE
MODULE
IN
OUT
W
Y
G
4500
THERMOSTAT
67
8
5
4
3
Figure 3. 4500 Thermostat with HVAC System