Honeywell CT70A User Manual
Thermometer Scale Range: 45
Installation Instructions
o
F to 85o F [7o C to 29o C].
Electrical Ratings: 24 to 27 Vac.
Do-It-Yourself Models
Your Honeywell Thermostat
Your new Honeywell CT70A Heat Pump Thermostat
provides low voltage (24 Vac) control of two-stage heating
and one-stage cooling in heat pump systems, using
manual changeover. Light-emitting diodes (LEDs) provide
emergency heat and auxiliary heat indication.
Recycling Notice
This control contains mercury in a sealed tube. Do not
place control in the trash at the end of its useful life.
M3375
1 PREPARATION
Your Honeywell thermostat should be properly
installed if you follow these instructions step-by-step.
It is recommended that as you read, understand and
complete each step, you check ✔ it off with pencil or pen.
Check thermostat suitability for your home’s system
by reviewing the ratings listed on the front of these
instructions and reviewing the CT70 Heat Pump Thermostat Wiring Guide enclosed.
CT70A
Heat Pump Thermostat
If this control is replacing a control that contains mercury in
a sealed tube, do not place your old control in the trash.
Contact your local waste management authority for
instructions regarding recycling and the proper disposal of
this control, or of an old control containing mercury in a
sealed tube.
If you have questions, call Honeywell Inc. at
1-800-468-1502.
Make certain that your home’s heat pump system is
working, especially if it has been inoperative for a
length of time. If the system does not work, contact your
local heating dealer for assistance.
Carefully unpack your new thermostat. Save
packages of screws, instructions, receipt and proofof-purchase.
2 THERMOSTAT MOUNTING DIMENSIONS
11
4 [119]
1
2 [52]
16
9
3
32
[83]
3
[5]
16
S.M. • 8-94 • Printed in U.S.A. • • ©Honeywell Inc. 1994 • Form Number 69-0846
16
EM. HEAT HEAT OFF COOL
31
3 [101]
32
1
[13]
2
3
[10]
80
70
60
8
11
[9]
32
3
8
[10]
9
1
32
[33]
9
3 [83]
32
80
70
60
50
50
AUTO ON
M3375
EM. HEAT AUX. HEAT
M7306
3 REMOVE OLD THERMOSTAT
BACK OF DEVICE
WARNING
Begin by turning off power to the heat pump at the
main service panel.
Remove cover of old thermostat—cover normally
snaps off when pulled firmly from the bottom. If it
resists, check for a screw that locks the cover.
Before removing the old thermostat from the wall,
look at it carefully to locate the heat anticipator
adjustment mechanism. (See illustration to help you
recognize the heat anticipator.)
MERCURY
SWITCH
ANTICIPATOR
SCALE
Make a note here of that anticipator setting for
reference in setting the anticipator on your new thermostat.
The heat anticipator pointer, if adjustable, will be set at one
of a series of numbers representing the current rating for
the primary control of your heat pump. The number will be
one of the following: .2, .4, .8, etc., or 0.2, 0.4, 0.8, etc. If
no heat anticipator indication is showing, do not be
concerned for now; go on to the next step.
Loosen screws holding thermostat base to wall and
lift away.
Disconnect wires from old thermostat. As you
disconnect each wire, tape the end and label it with
the enclosed wiring labels to make reconnection to new
thermostat easier.
Check the old insulation for cracks, nicks or fraying,
and apply high quality plastic tape where necessary
for adequate insulation.
Retain the old thermostat for reference purposes
and until your new thermostat is functioning
smoothly.
ANTICIPATOR
SETTING LEVER
M8449
4 WIRE AND MOUNT NEW THERMOSTAT
This thermostat can be mounted directly to the wall
or on a horizontal outlet box. Choose the method
that best fits your installation.
Grasp the thermostat cover at the top and bottom
with one hand. Pull outward on bottom edge of the
cover until it snaps free of the thermostat base. Carefully
remove and save the packing material surrounding the
mercury switches.
4
X
LB
W2
3
R
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
1
REMOVE W1-Y1 JUMPER WHEN HEAT RELAY 1 IS USED.
2
WHEN L TERMINAL IS CONNECTED TO SYSTEM MONITOR, EM. HEAT. LED ALSO INDICATES COMPRESSOR MALFUNCTION.
3
X TERMINAL MUST BE CONNECTED FOR PROPER OPERATION.
4
2
OEG
Y1
W1
Run wiring (if necessary) to the location. If the
wiring is plastered into the wall, make a hole next to
the cable and loosen the wires so that they can be pushed
back into the wall later. Thread wires through the hole in
packing material saved above. Connect the wires to the
terminals on the back of the thermostat according to the
labels you placed on the wires or as shown in the wiring
diagram.
L1
(HOT)
L2
1
EM. HEAT
RELAY
AUX. HEAT
RELAY
HEAT RELAY 1
M8447
SYSTEM
MONITOR
CHANGEOVER
RELAY (COOL)
FAN RELAY
CHANGEOVER
RELAY (HEAT)
COMPRESSOR
CONTACTOR
69-0846 2
Loading...