TB7220U ULTRASTAT PROGRAMMABLE THERMOSTAT
3 62-0223—1
Table 2. Terminal Designation Descriptions.
NOTES:
1. When used in a single-transformer system,
leave metal jumper wire in place between RC
and R. If used on a two-transformer system,
remove metal jumper wire between RC and
R.
2. Common wire is optional when thermostat is
used with batteries. When using separate
transformers for heating and cooling, the
common must come from the cooling
transformer.
3. If thermostat is configured for a heat pump in
the Installer Setup, configure changeover
valve for cool (O-factory setting) or heat (B).
4. Sensor wires must have a cable separate
from the thermostat control cable.
Table 3. Wiring Diagrams.
Terminal Designation Description
RC (see Note 1) Power for cooling—connect to secondary side of cooling system transformer.
R (see Note 1) Power for heating—connect to secondary side of heating system transformer.
Y Compressor output.
C (see Note 2) Common wire from secondary side of cooling system transformer.
WHeat relay.
G Fan relay.
W2 Second stage heat relay.
Y2 Second stage cooling.
O/B (see Note 3) Changeover valve for heat pumps.
S1 (See Note 4) Optional outdoor or indoor remote sensor.
S2 (See Note 4) Optional outdoor or indoor remote sensor.
System Type
Wallplate
Terminal
Identifications
Wiring
Diagram
Figure
Standard Heat/Cool Conventional 6, 7
Heat Only Conventional 8
Heat Only with Fan Conventional 9
Cool only Conventional 10
Standard Multistage
up to 2 Heat/2 Cool
Conventional 11, 12
Heat Pump
(No Auxiliary Heat)
Heat Pump 13, 14
Heat Pump
(with Auxiliary Heat)
Heat Pump 15, 16
Multiple T7770A Sensors — 17, 18, 19
Multiple C7189U Sensors — 20
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