CT500 ELECTRONIC THERMOSTAT
3
69-1525—2
Three Thermostat Wires
If you have three wires for heating only and can operate
the fan using the Fan On switch, this thermostat works
with your system. However, some hot water (zoned)
heating systems have three thermostat wires. The
thermostat works only if you install an isolating relay on
these systems. For details, contact your local heating
and/or air conditioning contractor.
3 MOUNT WALLPLATE
IMPORTANT
Level for appearance only. The thermostat func-
tions normally, even when not mounted level.
❑
Position the decorator cover plate and wallplate on
the wall. Level the wallplate for appearance, if
desired. Use a pencil to mark the two mounting holes
that best fit the application. See Fig. 3
Fig. 3. Mounting decorator cover plate and wallplate
to the wall.
❑
Remove the decorator cover plate and wallplate from
the wall, and drill two 3/16-in. holes in the wall (if
drywall). For firmer wall material such as plaster or
wood, drill 7/32-in. holes. Gently tap provided anchors
into the drilled holes until flush with the wall.
❑
Reposition the decorator cover plate and wallplate,
pulling wires through the wiring opening. Loosely
insert the mounting screws into the holes.
❑
Level for appearance only; the thermostat functions
correctly, even when not level. Tighten the mounting
screws.
4 WIRE WALLPLATE TERMINALS
The CT500 Thermostat is powered through the heating/
cooling system and is adaptable to most 4-wire, 18 to 30
Vac heating-cooling systems. Refer to Fig. 4 and 5 for
typical system wiring diagrams.
Fig. 4. CT500 wiring diagram, 4-wire heat/cool
system.
Fig. 5. CT500 wiring diagram, 2-wire, heat-only
system.
IMPORTANT
Use 18-gauge maximum wire to wire the ther-
mostat.
All wiring must comply with local electrical codes and
ordinances. If unsure about household wiring
procedures, call your local heating and air conditioning
contractor.
Refer to the wiring labels you placed on the wires when
you removed your old thermostat.
❑
Match the letter of your old thermostat wire with the
terminal of the corresponding letter on your new
thermostat. See Fig. 6.
NOTE: To ensure correct mounting of the thermostat,
restrict all wiring to the left side of the terminals.
❑
Loosen the terminal screws and slip each wire
beneath its matching terminal. The shape of the
terminals permit insertion of straight or wraparound
connections. See Fig. 7. Tighten the terminals.
❑
Plug the hole in the wall with insulation to help prevent
drafts from adversely affecting thermostat operation.
M14871
WALL
1
2
1
2
3-7/8 IN. x 3-7/8 IN. DECORATOR COVER PLATE (SELECT MODELS).
DRILL 3/16 INCH HOLES (IF DRYWALL) OR 7/32 (PLASTER OR WOOD)
WHEN USING WALL ANCHORS.
5-3/4 IN. x 5-3/4 IN.
DECORATOR
COVER PLATE
WALL
ANCHORS (2)
L1
(HOT)
L2
1
1
W
Y
G
R
COOLING
CONTACTOR
FAN
RELAY
HEATING
PRIMARY
CONTROL
24V
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
M14872
CT500A
L1
(HOT)
L2
1
1
W
Y
G
R
HEATING
PRIMARY
CONTROL
24V
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
M14873
CT500A