Special Wiring Instructions
Clock thermostat with C or C1 terminals
A clock thermostat has one or two extra wires attached to C or C1 terminals for clock operation that are not used when
installating your thermostat. They must be insulated from each other to avoid damaging your electrical circuit.
a. Make sure that power to the heating/cooling system is turned off.
b. Locate wires that are connected to clock terminals marked C or C1.
As you disconnect the wires, do not allow these wires to touch.
d. Wrap wires separately, using electrical tape to insulate the wires.
e. Place wires to avoid interfering with new thermostat operation. They are not used with your 3300 Thermostat.
Continue with the installation.
Six or more wires
If old thermostat has six or more wires (excluding clock wires attached to C or C1 terminals), your heating/cooling
system is a variation of a heat pump or multistage system. See thermostat compatibility table located before
Step 1. Your 3300 Thermostat does not work with such systems and should be returned to the place of purchase.
Three thermostat wires
If you have three wires for heating only and can operate the fan using Fan On switch, the 3300 Thermostat works with
your system. Continue installation procedure. If you have three-wire heating-only system and cannot operate fan using
Fan On switch, the 3300 Thermostat does not work with your system. Contact your heating contractor for installation.
Wires that are not connected to old thermostat
For extra wires that do not connect to your old thermostat, do not label them or connect these wires. Tape them with
electrical tape and place them to avoid interfering with operation of new thermostat. Continue installation procedure.
Five wires connected to old thermostat
Your new thermostat has a factory-installed metal
jumper between the R and Rc terminals (Fig. 15).
Remove jumper before wiring R and Rc terminals.
IF 5-WIRE SYSTEM