CT500 ELECTRONIC THERMOSTAT
69-1525—2
2
Not compatible with any 120/240 volt circuit.
Not compatible with 2-wire White-Rodgers no. 1361 zone valves.
a
Not compatible with millivolt systems.
b
Compatible with 2-wire Honeywell zone valves. Isolating relay required for 3-wire thermostat zone valves.
2 REMOVE OLD THERMOSTAT
❑
Test to be sure your heating and air conditioning
systems (where applicable) are working correctly. If
either does not work, contact you local heating/air
conditioning dealer. To avoid compressor damage, do
not operate the cooling system when outdoor
temperature is below 50°F (10°C).
CAUTION
Be careful when handling wires during
installation.
Damage to heating/cooling system possible.
Disconnect power at furnace or at main breaker/
fuse box before starting operation.
❑
Carefully unpack your new thermostat, wallplate, and
decorator cover plate; save package of screws,
instructions and receipt.
❑
Remove the cover from the old thermostat. If it does
not snap off when pulled firmly from the bottom, check
for a screw used to lock on the cover.
❑
Loosen screws holding the thermostat to the subbase,
wallplate and wall, and lift away.
❑
Disconnect wires from old thermostat or subbase. As
you disconnect each wire, use wire labels to identify
the old terminal designation. If there are only two
wires, they do not need labeling. Wrap wires around a
pencil to keep them from falling back into the wall as
shown in Fig. 2.
Fig. 2. Wrapping wires around pencil.
Replacing Clock With C or C1 Clock
Terminals
If you are replacing a Honeywell Chronotherm®
Thermostat, you may find one or two wires that go to the
C or C1 clock terminals on the Chronotherm®
Thermostat wiring wallplate. Do not allow them to touch,
or you can damage your transformer. Disconnect the
wires and wrap them separately using electrical tape; do
not wrap them together. Place the wires to avoid
interfering with the new thermostat operation. Record the
colors and terminal designation labels of the remaining
wires.
Six or More Wires
If there are six or more wires connected to the thermostat
(excluding clock wires attached to terminals), you
probably have a variation of a multistage heat pump or
other multistage system. The thermostat is not
compatible with such systems, so return the product to
your retailer. For information about which programmable
thermostats work with your system, call the Honeywell
Customer Relations Center at 1-800-468-1502.
Table 1. System Compatibility
System Type
Compatible with CT500
Gas — Standing Pilot
Yes
a
Gas — Electronic Ignition
Yes
Gas-Fired Boilers
Yes
a,b
Gas — Millivolt
No
Oil-Fired Boilers
Yes
b
Oil-Fired Furnace
Yes
Electric Furnace
No
Electric Air Conditioning
Yes
Baseboard Electric (120/240 Line Volt)
No
Heat Pumps/Multistage Equipment
No
WIRES THROUGH
WALL OPENING
M5136
