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3 69-1944EFS—01
MCR37992
UP
VERT.
UP
HORIZ.
R
Rc
G
W
E
F
Y
0
UP
HORIZ.
1. Pull wires through wire hole.
Position base on wall, level
and mark hole positions.
2. Drill holes (3/16” holes for
drywall, 7/32” holes for plas-
ter), then tap in supplied wall
anchors.
3. Pull wires through base, posi-
tion over anchors, and insert
screws. Check level if desired,
then tighten screws.
Base installation
1. Loosen screw terminals, insert bare wires
beneath screws, then re-tighten screws.
2. Push any excess wire back into the wall opening.
3. Plug the wall opening with nonflammable
insulation to prevent drafts from affecting
thermostat operation.
Terminal Designations
R Heating power. Connect to secondary
side of heating system transformer.
Rc Cooling power. Connect to secondary
side of cooling system transformer.**
G Fan relay.
W Heat relay.**
B Heat pump changeover valve energized in
heating.
O Heat pump changeover valve energized in
cooling.
Y Compressor contactor.
**Not present in the T834L model.
Wiring
NOTES
R & Rc Terminals
In single-transformer system, leave
metal jumper in place between R
& Rc. Remove metal jumper if two-
transformer system.
Heat pump systems
If wiring to a heat pump, use a small
piece of wire (not supplied) to connect
terminals W and Y.
Wire Specifications
Use 18-gauge thermostat wire. Shielded
wire is not required.