15. If using a single stage heat pump system, set switch to HP.
16. Set the GAS/ELEC switch to either GAS for a gas/oil heating
system or ELEC for an electric heating system.
17. A temperature limiting jumper has been included in this thermo-
stat. Cutting this jumper (J3) limits the heating setpoint to no
greater than 72°F and the cooling setpoint to no lower than 78°F
(Figure 7).
6
Figure 6
TERMINAL LEGEND - 9550
TERM EQUIPMENT TO CONNECT REQ? TERMINAL FUNCTION
C 24VAC common connection Yes For input of 24VAC common
side of transformer
R 24VAC hot connection Yes For input of 24VAC hot side
of transformer
W First stage heat connection Yes* Energizes on a call for
heat
Y Second stage heat connection No Energizes on a call for
cooling
G Indoor fan connection Yes** Energizes with W (ELECTRIC
mode only) and Y or with
FAN option switched to the
ON position
O Cool active reversing valve No*** Energizes when in the
connection COOL mode
B Heat active reversing valve No*** Energizes when in the
connection HEAT or EM modes
* This thermostat can be used as a heat only or cool only thermostat therefore it is not always
necessary to use both W and Y.
** A heat only gas system typically will not require the G terminal connection unless a separate
indoor blower is installed.
*** Most heat pump systems will have a cool active OR
a heat active reversing valve. Use the
appropriate terminal.
