CT41A
Heating/Cooling Thermostat
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
Heating/Cooling
15 to 30 Vac Thermostat
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.
Congratulations on the purchase of your new thermostat!
YOUR NEW CT41A THERMOSTAT
SCREWDRIVER
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.
HAND OR POWER
DRILL WITH 3/16 INCH
DRILL BIT, IF NEEDED TO
DRILL HOLES IN WALL
Direct questions about this thermostat to our Web site at
information line at 1-800-468-1502.
WIRE CUTTER/STRIPPER IF NEEDED TO STRIP WIRES
MERCURY
SWITCH
LEVEL, IF NEEDED TO LEVEL
M20551
THERMOSTAT FOR APPEARANCE
Fig. 1. Required installation tools/supplies.
TYPICAL LOCATION OF A MERCURY
SWITCH IN A THERMOSTAT
M10614
® U.S. Registered Trademark
Copyright © 2003 Honeywell International Inc •
• All Rights
69-0788-2
CT41A HEATING/COOLING THERMOSTAT
❑ Push excess wire back into wall and plug hole with
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.
SHOWS
VOLTAGE
RATING
V8043E 1004
24V 50/60CY
4
SHOWS
ANTICIPATOR
SETTING
.32 AMP
@
60CY
❑ 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.)
ZONE VALVE
OIL BURNER CONTROL
SHOWS
SHOWS
VOLTAGE
RATING
CURRENT
DRAW
30 VAC
0.2 AMP
BUBBLE LEVEL
SHOWS
VOLTAGE
RATING
T
T
TO
BURNER
F
F
24 Vac 50/60 Hz
0.4 AMP
FROM MAIN
SHOWS
FUEL SUPPLY
ANTICIPATOR
SETTING
M6116B
TYPICAL GAS VALVE
PLUMB
.18
LINE
.9
.7
.2
.5
.25
Fig. 6. Locate your system current draw anticipator
setting.
3
❑ Set the heat anticipator indicator at the rating printed
on the primary control. See Fig. 7.
PLUMB
BOB OR
WEIGHT
M3774
CAUTION
Heat Anticipator Hazard.
Fig. 5. Level thermostat.
Setting heat anticipator too low can cause
anticipator burnout.
❑ Recheck for level positioning and firmly tighten both
mounting screws.
Set heat anticipator at recommended rating to
avoid shorting out your valve or control and
prevent burnout of your heat anticipator.
❑ 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.)
SCALEPLATE
.18
.9
.2
.7
ADJUSTABLE
HEAT
ANTICIPATOR
.5
.25
3
SETTING LEVER
M3784
Fig. 7. Set heat anticipator indicator to match your
primary control rating.
❑ Press thermostat cover firmly onto the mounting clips.
See Fig. 2.
3
69-0788-2
CT41A HEATING/COOLING THERMOSTAT
4 CHECK OUT THERMOSTAT
The System switch controls as follows:
Heat: heating system only operates.
Off: heating and air conditioning systems are discon-
nected.
❑ Observe system operation for at least one cycle on
both heating and air conditioning. To observe:
❑ Place the System switch at the Heat position and the
Fan switch at the Auto position. Move the temperature
setting lever 10°F (6°C) below room temperature. The
heating equipment should turn on. A short warmup
period may be required before system fan turns on.
Cool: air conditioning system only operates.
The Fan switch controls as follows:
Auto: fan operates when heating or air conditioning
system operates.
NOTE: Some systems have a time delay that can pre-
vent operation up to five minutes.
On: fan operates continuously.
❑ Turn the Fan switch to On. The system fan should turn
on and operate continuously. The system blower
should continue to operate at any System switch or
thermostat setting.
NOTE: In the following instructions, disregard heating
or air conditioning directions if not applicable to
your system.
5 THERMOSTAT
CAUTION
Compressor Damage Hazard.
Operating at too low of an outdoor
temperature can cause compressor damage.
Do not operate cooling if outdoor temperature is
below 50°F (10°C).
❑ Place the System and Fan switches at the desired
settings for operation.
Allow compressor to remain off for five minutes
before restarting.
6 TROUBLESHOOTING (TABLE 2)
Refer to manufacturer’s recommendations.
Your Honeywell thermostat requires little or no attention.
Most problems can be resolved according to Table 2.
❑ Turn on power to the heating/air conditioning system.
NOTE: If your system is heating-only or air
conditioning-only, disregard sections not
applicable to your system.
69-0788-2
4
CT41A HEATING/COOLING THERMOSTAT
Table 2. Recommended Corrective Action for Your System.
Symptom
No heat
Problem
Corrective Action
Move System switch to Heat position.
Replace fuse or reset circuit breaker.
Turn furnace power switch to On.
System switch is at Off of Cool position.
Blown fuse or tripped circuit breaker.
Furnace power switch is at Off.
No pilot flame.
Relight pilot flame according to furnace
manufacturer instructions.
Incorrect connections to thermostat.
With power to furnace at Off, tighten all
mounting and terminal screws. Repair frayed or
broken wires.
Other.
Contact a qualified service technician for
assistance.
Furnace turns on and
off.
Burner On period is too short.
Remove the thermostat cover and move the
heat anticipator lever counterclockwise (left)
one scale mark. Replace the cover and wait
several hours for the system to stabilize.
Major swings in
temperature greater
than 2°F (1°C) when
outside temperature is
stable.
Burner On period is too long.
Remove the thermostat cover and move the
heat anticipator lever clockwise (right) one
scale mark. Replace the cover and wait several
hours for the system to stabilize.
Thermostat setting and Thermostat is not level.
thermometer reading
disagree.
Recheck the thermostat position on the wall.
Use bubble level to make sure it is level. See
step 3 and Fig. 5.
Thermostat is affected by drafts or radiant Contact a qualified service technician to change
heat.
the location.
Thermometer is out-of-calibration.
System switch is in Off or Heat position.
Blown fuse or tripped circuit breaker.
Recalibrate. See step 7.
Move switch to Cool position.
Replace fuse or reset circuit breaker.
Move switch to On position.
No air conditioning.
Compressor switch (located outdoors) is
turned off.
Incorrect connections to thermostat.
With power to system off, tighten all mounting
and terminal screws. Repair broken wires.
Other.
Contact service technician for assistance.
5
69-0788-2
CT41A HEATING/COOLING THERMOSTAT
7 RECALIBRATE THERMOMETER
If the thermostat setpoint and the thermometer reading
do not agree, the thermometer may need recalibration.
BACKSIDE
OF COVER
Follow this procedure:
❑ Remove thermostat cover.
❑ Set the cover on a table near an accurate
thermometer.
THERMOMETER
SHAFT
❑ After allowing five or ten minutes for stabilization,
compare the readings.
❑ If the readings are the same, replace the cover and
put the system into operation.
❑ If the readings are different, insert a hex head wrench
into the thermostat shaft and turn it until the
thermometers have the same reading. See Fig. 8.
❑ Replace cover and put the system into operation.
HEX HEAD
WRENCH
M8068
Fig. 8. Adjusting thermometer calibration.
69-0788-2
6
CT41A HEATING/COOLING THERMOSTAT
Limited One-Year Warranty
Honeywell warrants this product, excluding battery, to be free from defects in the workmanship or materials, under normal use and service, for a period of
one (1) year from the date of purchase by the consumer. If, at any time during the warranty period, the product is defective or malfunctions, Honeywell shall
repair or replace it (at Honeywell’s option) within a reasonable period of time.
If the product is defective,
(i) return it, with a bill of sale or other dated proof of purchase, to the retailer from which you purchased it, or
(ii) package it carefully, along with proof of purchase (including date of purchase) and a short description of the malfunction, and mail it, postage prepaid,
to the following address:
Honeywell Return Goods
Dock 4, MN10-3860
Canada: Honeywell Limited/Honeywell Limitée
Product Services ON15
1885 Douglas Dr N
35 Dynamic Dr
Golden Valley, MN 55422
Scarborough, Ontario M1V 4Z9
This warranty does not cover removal or reinstallation costs. This warranty shall not apply if it is shown by Honeywell that the defect or malfunction was
caused by damage which occurred while the product was in the possession of a consumer.
Honeywell’s sole responsibility shall be to repair or replace the product within the terms stated above. HONEYWELL SHALL NOT BE LIABLE FOR ANY
LOSS OR DAMAGE OF ANY KIND, INCLUDING ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING, DIRECTLY OR INDIRECTLY,
FROM ANY BREACH OF ANY WARRANTY, EXPRESS OR IMPLIED, OR ANY OTHER FAILURE OF THIS PRODUCT. Some states do not allow the
exclusion or limitation of incidental or consequential damages, so this limitation may not apply to you.
THIS WARRANTY IS THE ONLY EXPRESS WARRANTY HONEYWELL MAKES ON THIS PRODUCT. THE DURATION OF ANY IMPLIED
WARRANTIES, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, IS HEREBY LIMITED TO
THE ONE YEAR DURATION OF THIS WARRANTY. Some states do not allow limitations on how long an implied warranty lasts, so the above limitation
may not apply to you.
This warranty gives you specific legal rights, and you may have other rights which vary from state to state.
If you have any questions concerning this warranty, please write Honeywell Customer Relations, 1985 Douglas Dr N, MN10-1461, Golden Valley, MN
55422. In Canada, write Retail Products ON15, Honeywell Limited/Honeywell Limitée, 35 Dynamic Dr, Scarborough, Ontario M1V 4Z9.
7
69-0788-2
CT41A HEATING/COOLING THERMOSTAT
Automation and Control Solutions
Honeywell International Inc.
1985 Douglas Drive North
Golden Valley, MN 55422
Honeywell Limited-Honeywell Limitée
35 Dynamic Drive
Scarborough, Ontario
M1V 4Z9
Printed in U.S.A. on recycled
paper containing at least 10%
post-consumer paper fibers.
69-0788—2 G.H. Rev. 10-03
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