*
Common wire is not required in most heat/cool installations.
Use only if heat, cool, or fan relay cannot supply 15mA to
power thermostat, without activating.
Figure 7 -
Single stage heat/cool thermostat
*
Do not connect RC and RH together.
Figure 8 -
Heating & cooling with separate transformers
COOL
RELAY
RELAY
FAN
R
Y
C
W
G
COMMON
RELAY
HEAT
*
TRANSFORMER
CONTROL
24VAC
G
W
C
Y
R
RELAY
RELAY
RELAY
HEAT
COOL
FAN
24VAC COIL RELAY
(NOT SUPPLIED)
24VAC (RH)
CONTROL
CONTROL
TRANSFORMER
24VAC (RC)
TRANSFORMER
8