Wiring; Terminal Designations - Honeywell PRO TH4110B Installation Manual

Installation Guide

Wiring

CAUTION: ELECTRICAL HAZARD. Can cause electrical shock or equipment damage.
Disconnect power before wiring.
Keep wires in this
shaded area
Terminal
block
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- to 22-gauge thermostat wire.
Shielded cable is not required.
Wiring
1 Loosen screw terminals, insert
Jumper
2 Push excess wire back into the
3 Plug the wall opening with non-

Terminal Designations

W W Heat relay.
Y Y Compressor contactor.
G G Fan relay.
O O Heat pump changeover valve
R R c c Cooling power. Connect to
R R Heating power. Connect to
B B Heat pump changeover valve
4
wires into terminal block, then
re-tighten screws.
wall opening. Keep wires in shaded
area as shown at left.
flammable insulation to prevent
drafts from affecting thermostat
operation.
energized in cooling.
secondary side of cooling
system transformer.
secondary side of heating
system transformer.
energized in heating.