Honeywell CT41A User Manual
Heating/Cooling Thermostat
Y
T
S
Heating/Cooling
15 to 30 Vac Thermostat
Congratulations on the purchase of your new thermostat!
CT41A
INSTALLATION INSTRUCTIONS
MERCURY NOTICE
If this control is replacing a control that contains
mercury in a sealed tube, do not place your old
control in the trash. Dispose of it properly.
Contact your local waste management authority
for instructions regarding recycling and the
proper disposal of an old control.
1 PREPARE FOR INSTALLATION
If you are unsure about wiring procedures, please call a
qualified service technician for assistance.
❑ To correctly install your new thermostat, follow these
step-by-step instructions. It is recommended that, as
you read, understand, and complete each step, you
place a check mark in each box provided.
❑ See Your New CT41A Thermostat section above to
determine the thermostat suitability for compatibility
with your home system. If not, return it to the retailer.
Acquire the required installation tools and supplies, as
needed. See Fig. 1.
YOUR NEW CT41A THERMOSTAT
Your new CT41A Thermostat replaces most 15 to 30V,
4-wire, heating/cooling system thermostats. The CT41A
is suitable for gas or oil heat or electric air conditioning
systems.
Direct questions about this thermostat to our Web site at
www.honeywell.com/yourhome or call the customer
information line at 1-800-468-1502.
MERCUR
SWITCH
YPICAL LOCATION OF A MERCURY
WITCH IN A THERMOSTAT
® U.S. Registered Trademark
Copyright © 2003 Honeywell International Inc • • All Rights
M10614
SCREWDRIVER
WIRE CUTTER/STRIPPER IF NEEDED TO STRIP WIRES
LEVEL, IF NEEDED TO LEVEL
THERMOSTAT FOR APPEARANCE
Fig. 1. Required installation tools/supplies.
HAND OR POWER
DRILL WITH 3/16 INCH
DRILL BIT, IF NEEDED TO
DRILL HOLES IN WALL
69-0788-2
M20551
CT41A HEATING/COOLING THERMOSTAT
H
2 REMOVE OLD THERMOSTAT
❑ Test to be sure your heating and air conditioning
systems (where applicable) are working correctly. If
not, contact your 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
Equipment Damage Hazard.
Handling wires during installation can
damage equipment.
Disconnect power at furnace or main breaker/
fuse box before beginning installation.
❑ Carefully unpack your new thermostat and save the
package of screws, the instructions and the receipt.
❑ Remove the cover from the old thermostat. If it does
not snap off when pulled firmly from the bottom, 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, see Fig. 2. Make a note here ________
of the 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 primary control of your system (in
amperes). The numbers range from 0.18 to 1.0. If no
heat anticipator/indication is showing, do not be
concerned; move on to the next step.
TOP MOUNTING HOLE
(THERMOSTAT TO WALL
OR OUTLET BOX)
ADJUSTABLE HEAT
ANTICIPATOR
.18
.9
.2
.7
.5
.25
3
Fig. 2. Locating heat anticipator adjustment
❑ Loosen screws holding thermostat to subbase,
wallplate or wall and lift away.
❑ Disconnect wires from old thermostat or subbase. As
you disconnect each wire, tape the end and label it
with the letter of the terminal designation. If there are
only two wires, they do not require labeling. Wrap
wires around a pencil to keep them from falling back
into the wall as shown in Fig. 3.
mechanism.
SETTING LEVER
MOUNTING CLIPS
(FOR COVER)
FAN SWITCH
SYSTEM SWITCH
BOTTOM
MOUNTING HOLE
TEMPERATURE
SETTING LEVER
M3782A
WIRES THROUG
WALL OPENING
M5136
Fig. 3. Wrapping wires around pencil.
❑ Keep the old thermostat for reference until your new
thermostat is functioning smoothly.
3 WIRE AND MOUNT THERMOSTAT
❑ Connect wires from the wall to the matching terminals
on the back of the thermostat. See Fig. 4. Tighten the
screws.
NOTE: If terminal designations on old thermostat do not
match those on new thermostat, see Table 1.
Table 1. Terminal Functions.
New
Old Thermostat
Terminal Marking Function
G or F Fan G
Y or C or M or Y
W or H or W
1
Cooling Y
1
Heating W
RC, V, VC or B Power Your 5-wire
RH, M, VR, 4, A or RPower R
W
Y
Thermostat
system cannot
use this
thermostat;
use a CT87B
instead.
R
G
Ter mina l
Marking
69-0788-2 2
TERMINAL SCREWS
Fig. 4. Connect wires from wall to thermostat
matching terminals.
M8067A
❑ Push excess wire back into wall and plug hole with
M3774
T
F
F
4
R
nonflammable insulation to prevent drafts from
affecting thermostat operation.
❑ Remove thermostat cover by pulling outward on right
edge of cover until it snaps free of the thermostat
base.
❑ Fasten thermostat to wall or vertical outlet box with a
screw through the top mounting hole. See Fig. 2 for
hole location.
❑ Place a bubble level or plumb line against the
thermostat to find the level position. See Fig. 5. Start a
screw in the center of the bottom mounting hole.
(Move the temperature setting lever, if necessary, to
uncover the mounting hole.)
BUBBLE LEVEL
.18
.9
.2
.7
.5
.25
3
PLUMB
LINE
PLUMB
BOB OR
WEIGH
Fig. 5. Level thermostat.
❑ Recheck for level positioning and firmly tighten both
mounting screws.
❑ Be sure you have the current draw anticipator setting
for your system. This is the number you wrote in the
box in step 2 Remove Old Thermostat section. If you
could not find the current draw for step 2, look on your
primary control at the furnace. See Fig. 6. (The
primary control is usually a gas valve, zone valve, or a
relay or burner control box with the thermostat wires
connected to it. For electric heat, add the fan relay
current, usually 0.2A to 0.4A.)
CT41A HEATING/COOLING THERMOSTAT
SHOWS
VOLTAGE
8406
RATING
SHOWS
ANTICIPATOR
SETTING
SHOWS
CURRENT
DRAW
SHOWS
VOLTAGE
RATING
ROM MAIN
UEL SUPPLY
24 Vac 50/60 Hz
0.4 AMP
TYPICAL GAS VALVE
Fig. 6. Locate your system current draw anticipator
❑ Set the heat anticipator indicator at the rating printed
on the primary control. See Fig. 7.
setting.
TO
BURNER
SHOWS
ANTICIPATOR
SETTING
V8043E 1004 4
24V 50/60CY
@ 60CY
.32 AMP
ZONE VALVE
OIL BURNER CONTROL
0.2 AMP
30 VAC
SHOWS
VOLTAGE
RATING
M6116B
T
T
F
F
CAUTION
Heat Anticipator Hazard.
Setting heat anticipator too low can cause
anticipator burnout.
Set heat anticipator at recommended rating to
avoid shorting out your valve or control and
prevent burnout of your heat anticipator.
.18
.9
.2
.7
.5
.25
3
SCALEPLATE
ADJUSTABLE
HEAT
ANTICIPATOR
SETTING LEVE
M378
Fig. 7. Set heat anticipator indicator to match your
❑ Press thermostat cover firmly onto the mounting clips.
See Fig. 2.
3 69-0788-2
primary control rating.
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