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WIRING DIAGRAM NOTES:
(Important, please read all notes before connecting wires)
• If the information provided in the following wiring diagrams does not
clearly represent or match your system, please refer to the “TECHNICAL
ASSISTANCE” section of this manual, and contact us
before
removing any
of your existing thermostat wiring.
• All of the dashed wires shown in the wiring diagrams are either optional,
or their usage depends upon your specific system type or brand. For
example: Diagram #1 shows the fan wire as optional. If your system does
not have a fan, than this terminal will not be used.
• Terminal letters shown in black represent typical wiring applications.
Depending upon the brand of your specific system or thermostat, your
terminal letters may not match exactly. Terminal letters shown in gray
represent other possible wiring designations that you might see on your
existing thermostat terminals.
• The optional “C” terminal is used for powering the thermostat by the 24-
volt system, using the System Common wire. This can be used alone, or
in addition to installing batteries as a backup. NOTE: connecting the
System Common wire to the thermostat is not necessary for heating and
cooling to function properly.
• If your old thermostat has both a “Y” and “C” wire present, then “C” is
most likely a System Common wire.
• For Heat Pump systems, you will use either the “O” terminal or the “B”
terminal on this thermostat, but not both. If your old thermostat has both
an “O” and a “B” wire present, then “B” is likely a System Common wire
and may be connected to the “C” terminal. Connecting a System Common
wire to this thermostat’s “B” terminal may damage the thermostat, and
also your heating and cooling system.
• Some Heat Pump systems have a wire for AUX electric heat (usually W2),
and also a separate wire for Emergency electric heat (usually E). This
thermostat uses the W2 terminal for both AUX and Emergency Heat. Tape
off your “E” wire, and confirm that all components function without it.
• If replacing an old thermostat that has a mechanical clock, there may be
two
wires labeled as “C” for the clock power. Tape off these wires and do
not connect them to the “C” terminal of this thermostat.
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