Remove Old Thermostat; Check Out Thermostat; Wire And Mount New Thermostat - Honeywell CT40A Installation Instructions Manual

CT40A HEATING THERMOSTAT
ADJUSTABLE
HEAT
ANTICIPATOR
INDICATOR
MOUNTING HOLE
(THERMOSTAT
TO WALL OR
OUTLET BOX)
Fig. 2. Reviewing your thermostat features.

3 Remove Old Thermostat

First, turn off power to heating system at main fuse
panel. (Most residential systems have a separate
switch box or circuit breaker to disconnect power to
the furnace.)
Remove cover of old thermostat—cover normally
snaps off when pulled firmly from the bottom. If it
resists, check for a screw that locks on the cover.
Before removing the old thermostat from the wall, look
at it carefully to locate the heat anticipator adjustment
mechanism. Make a note here_______ of that
anticipator setting for future reference.
The heat anticipator pointer, if adjustable, is set at one
of a series of numbers representing the (electrical)
current rating of the heating system in amperes. The
number is one of the following: .2,.4,.8, etc., or 0.2,
0.4, 0.8, etc.
If you cannot find the heat anticipator setting on your
old thermostat, you can use the standard setting for
your type of system as listed in Table 1 in step 4.
Loosen screws holding thermostat base to subbase or
wall and lift away.
Disconnect wires from old thermostat. Wrap old wires
around pencil to ensure they do not fall back into the
wall opening. See Fig. 3.
Keep the old thermostat for reference until your new
thermostat is functioning smoothly.
Fig. 3. Keeping old wires from falling back into wall

4 Wire and Mount New Thermostat

Connect each wire from the wall to either terminal on
the back of the thermostat. Tighten the screws.
69-0847B-1
MOUNTING HOLE
(THERMOSTAT TO
WALL OR OUTLET BOX)
MOUNTING
POSTS (4)
(FOR COVER)
ADJUSTABLE
HEAT
ANTICIPATOR
SCALE
SNAP SWITCH
CONTACTS
MOUNTING
CLIPS (2)
(FOR COVER)
TEMPERATURE
SETTING LEVER
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opening.
Push excess wire back into the wall and plug the hole
with nonflammable insulation to prevent drafts from
affecting thermostat operation.
Grasp the thermostat cover at the sides with one
hand. Pull outward on the left edge of the thermostat
cover until it snaps free of the thermostat base.
Carefully remove and discard the shipping tab
protecting the snap switch contacts.
Fasten thermostat to wall or vertical outlet box with
screws through the two mounting holes at each side
of the thermostat. See Fig. 2 for hole location.
Level thermostat for appearance and firmly tighten
both mounting screws.
Identify the correct heat anticipator setting for your
system. This is the number you noted in step 3. If you
were unable to find the current draw for step 3, use
the setting for your type of system as listed in Table 1.
Set the heat anticipator to the setting for your system.
NOTE: If the heating system stays on after the thermo-
stat temperature setting, move the heat antici-
pator clockwise one scale mark. If the heating
system turns off before the temperature setting,
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move the heat anticipator counterclockwise one
scale mark. Never adjust the heat anticipator
below .3A.
Press the thermostat cover firmly onto the mounting
clips.
Table 1. Selecting Your Heat Anticipator Setting.
Your Heating System
Hot water heat
High efficiency warm air
Standard warm air
Electric heat
Fig. 4. Setting heat anticipator rating.

5 Check Out Thermostat

Turn on the power to the heating system.
Observe the system operation for at least one
complete cycle. Move the temperature setting lever 6°
C (10° F) above room temperature; the heating
equipment should turn on. Move the temperature
lever 6° C (10° F) below room temperature; the
heating equipment should turn off.
2
Your Heat
Anticipator Setting
0.8
0.8
0.4
0.3
HEAT ANTICIPATOR
SETTING LEVER
ANTICIPATOR SCALE
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