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13. Make sure wire connections are secure.
14. Push excess wire back through opening.
15. Set the Electric/Gas switch to either GAS for a gas/oil heating
system or ELEC for an electric heating system (Figure 5).
16. Set the HP option switch to either the HP for heat pump or
NON_HP for furnace applications (Figure 5).
17. Install two AA Energizer brand batteries or equivalent into
battery compartment as shown (Figure 5).
18. Replace thermostat cover by snapping into place.
7
RC
RH
GOBY1W1
ELEC GAS
NON_HP HP
°
F
+
–
+
–
Figure 5
TERMINAL LEGEND - 8400
TERM EQUIPMENT TO CONNECT REQ? TERMINAL FUNCTION
Rh 24VAC hot connection Yes For input of 24VAC hot
side of heat transformer
Rc 24VAC hot connection Yes For input of 24VAC hot
side of cool transformer
W1 Heat connection Yes* Energizes on a call for
heating
Y1 Compressor Connection Yes* Energizes on a call for
cooling
B Heat active reversing valve** No Energizes when in the
HEAT mode
O Cool active reversing valve** No Energizes when in the
COOL mode
G Indoor fan connection Yes Energizes with Y1 & W1
terminals or with FAN
option switched to the
ON position
* This thermostat can be used as a heat only or cool only thermostat. Therefore it is not always
necessary to use both Y and W.
**The O and B terminals are accessory terminals that typically are used for heat pump applications.
Correct battery
placement
ELECTRIC/GAS SWITCH
Selects fan control.
HP OPTION SWITCH
Heat pump switch.
110-1086B.qxd 3/8/05 10:26 AM Page 7