CT70
Heat Pump
Thermostat Wiring Guide
1
2
HOW TO USE THIS GUIDE
Before you disconnect the wires and remove your
existing thermostat, be sure this new thermostat, see the
CT70 wiring hookup diagram, will replace it and that you
understand how you will reconnect the wiring. To do that,
proceed as follows:
Step 1
Find the manufacturer of your heat pump in the Table of
Contents, and turn to the appropriate page.
Step 2
Expose the wiring on your existing thermostat (the
subbase) and check that the terminals on your existing
thermostat coincide with the terminals shown in the
second column (Existing thermostat wiring).
If they do, read and follow the installation instructions
provided with the thermostat.
If they do not, call Honeywell Customer Assistance toll
free at 1-800-468-1502, Monday-Friday, 7:00 a.m. - 5:30
p.m. Central time, to be sure you can safely use this
thermostat to control your heat pump.
Before you call, please have the following information
available: thermostat model number and date code, heat
pump model number and manufacturer, and number of
wires connected to the thermostat. The date code is
usually stamped on the back of the thermostat and is a
four-digit number; for example, 9346.
3
4
TABLE OF CONTENTS
How to Use This Guide ................................................. 3
Heat Pumps are Different .............................................. 6
Heat Pumps are Two Systems in One .......................... 7
Definitions of Terminal Functions ............................... 8,9
Heat Pump Manufacturers ..................................... 11-22
Amana....................................................................11
American Standard................................................ 20
Arcoaire................................................................. 13
Bard....................................................................... 12
Borg Warner ..................................................... 21,22
B.D.P. (Bryant-Day/Night-Payne) .......................... 14
Carrier ................................................................... 15
Comfortmaker ....................................................... 13
Friedrich ................................................................ 16
Heil Quaker ........................................................... 17
Janitrol................................................................... 12
Lennox .................................................................. 18
Luxaire (Moncrief, Fraser, Johnston) .................... 21
Rheem................................................................... 19
Ruud...................................................................... 19
Snyder General ..................................................... 13
Tappan .................................................................. 12
Tempstar ............................................................... 17
Trane..................................................................... 20
Whirlpool ............................................................... 17
Williamson............................................................. 12
York.................................................................. 21,22
5
HEAT PUMPS ARE DIFFERENT
Heat pump systems
usually have a
supplemental,
Second Stage
heating system that
operates only when
necessary. This
heat pump
thermostat is
designed to
minimize more
expensive secondÂstage operation,
indicated by the
green AUX. HEAT
light on your
thermostat.
6
HEAT PUMPS ARE TWO SYSTEMS IN ONE
OUTDOORS
OUTDOOR
AIR
HEAT
TRANSFER
In mild weather, virtually all of the demand for heat in
buildings can be met by the heat pump compressor.
First Stage process of moving heat indoors is very
economical. As the air becomes colder outside, the first
stage may be unable to deliver enough heat to maintain the
desired comfort level in the building.
OUTDOORS
OUTDOOR
AIR
HEAT
TRANSFER
During high heat demand, the thermostat will call for
additional Second Stage power from the auxiliary heat
system.
This auxiliary heat is commonly electric resistance
heat and is two to three times more expensive to operate
than the compressor. If you have specific questions
concerning the operation of your heat pump, please contact
the equipment manufacturer.
MILD WEATHER
SEVERE WEATHER
INDOORS
AUXILIARY
HEATING
ELEMENT
OFF
INDOOR
AIR
M9069
INDOORS
AUXILIARY
HEATING
ELEMENT
ON
INDOOR
AIR
M9078
This
7
DEFINITIONS OF TERMINAL FUNCTIONS
Each terminal of the CT70 controls a different heat pump
function. Here is a list of the possible heat pump
functions:
Function Definition
FIRST STG. HEAT:
AUXILIARY HEAT:
FIRST STG. COOL:
COMPRESSOR:
C/O VALVE HEAT:
C/O VALVE COOL:
EM. HEAT:
8
When this terminal is activated, the heat
pump is on and heating the living space.
When this terminal is activated, the
auxiliary heating source is on because the
heat pump is unable to meet the heating
demand of the living space.
When this terminal is activated, the heat
pump is on and cooling the living space.
When this terminal is activated, the heat
pump is on and either heating or cooling
the living space, depending on the system
switch position.
Heating Changeover Valve. This terminal
is activated when the system switch is in
the HEAT position. It provides changeover
in heat pumps that change over in
heating.
Cooling Changeover Valve. This terminal
is activated when the system switch is in
the COOL position. It provides
changeover in heat pumps that change
over in cooling.
Emergency Heat. This terminal is
activated when the system switch is in the
EM. HT position. In this situation, the heat
pump is not activated.
FAN:
MULTIPLE AUX.
HEAT LOADS:
OUTDOOR
SENSOR:
OUTDOOR STAT:
POWER:
COMMON:
SYSTEM MONITOR:
When this terminal is activated, the fan is
on. With the fan switch in the auto
position, the fan cycles on and off with the
heat pump. With the fan switch in the ON
position, the fan is
on continuously.
This terminal is activated when additional
auxiliary heat loads are required. Because
the CT70 only has provisions for one
auxiliary heat load, these loads must be
connected to the AUXILIARY HEAT
terminal.
This terminal is not connected to the
CT70. On your original thermostat, this
terminal was activated by an outdoor
sensor that controlled the auxiliary heat
source.
Outdoor Thermostat. This terminal is
activated when the system switch is in the
EM. HT. position. The outdoor thermostat
controls the amount of auxiliary heat that
is activated.
This terminal connects to the power side
of the 24-volt transformer.
This terminal connects to the common
side of the 24-volt transformer.
Some heat pumps have the ability to
indicate when the heat pump is
malfunctioning. When this occurs, this
terminal is activated and the EM. HT. LED
is activated.
9
L1
L2
(HOT)
AUX. HEAT
RELAY
CHANGEOVER
RELAY (HEAT)
1
FAN RELAY
EM. HEAT
RELAY
M8504
CHANGEOVER
RELAY (COOL)
SYSTEM
MONITOR
4
X
L
W2
3
R
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
1
PROTECTION AS REQUIRED.
REMOVE W1-Y1 JUMPER WHEN HEAT RELAY 1 IS USED.
2
WHEN L TERMINAL IS CONNECTED TO SYSTEM MONITOR, EM. HEAT. LED
3
ALSO INDICATES COMPRESSOR MALFUNCTION.
X TERMINAL MUST BE CONNECTED FOR PROPER OPERATION.
4
B
2
E
W1
O
Y1
G
HEAT RELAY 1
COMPRESSOR
CONTACTOR
Typical wiring hookup of CT70 with jumper intact.
10
AMANA
Wiring
terminal
function
COMMON
POWER
COMPRESSOR
ST
1
STG.
HEAT
AUX. HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
EM. HEAT
SYSTEM
MONITOR
!
Jumper these two terminals if both are present
# This terminal must be connected to transformer common.
$ Remove this factory-installed jumper for independent stage 1
heat and cool connection.
Existing
thermostat
wiring
C X
X1
or
1
RH RRC
R
or
or
Y1 Y1Y
or
W1
W2 W2
G G
W
or
O O
E E
New
thermostat
wiring
W1
BB
L
2
3
11
BARD/JANITROL/TAPPAN/WILLIAMSON
Wiring
terminal
function
COMMON
POWER
COMPRESSOR
ST
1
STG.
HEAT
AUX. HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
EM. HEAT
MULTIPLE AUX.
HEAT LOADS
This terminal must be connected to transformer common.
!
# Leave factory-installed jumper in place.
$ Connect multiple second stage heating loads to W2 terminals.
% Thermostat is connected to either O or B terminal, but not
both.
3
Existing
thermostat
wiring
C
or
RH
or
4
B
4
New
thermostat
1
X XX1
or
R RRC
or
Y Y1
W2 W2
G G
W1
or
O
L L
E E
W3
wiring
W1
1
2
B
O
3
12
ARCOAIRE/SNYDER GENERAL/COMFORTMAKER
Wiring
terminal
function
COMMON
POWER
COMPRESSOR
ST
1
STG.
HEAT
AUX. HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
EM. HEAT
! This terminal must be connected to transformer common.
# Leave factory-installed jumper in place.
Existing
thermostat
wiring
X,X1
W2
1
C X
or
R R
Y Y1
W1 W2
or
G G
O O
L
X
or
E E
New
thermostat
wiring
W1
B
L
1
2
13
B.D.P. (BRYANT-DAY/NIGHT-PAYNE)
Wiring
terminal
function
COMMON
POWER
COMPRESSOR
ST
STG.
1
HEAT
AUX. HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
EM. HEAT
MULTIPLE AUX.
HEAT LOADS
DEFROST
This terminal must be connected to transformer common.
!
# Leave factory-installed jumper in place.
$ Connect multiple second stage heating loads to W2 terminals.
3
Existing
thermostat
wiring
C1 X1
or
W1
Y1
L
X
New
thermostat
wiring
1
C
or
R R
Y
or
W2 W2
G G
B B
O O
or
F L
or
E
or
W3
P P
1
X
Y1
2
W1
3
E
14
CARRIER
Wiring
terminal
function
COMMON
POWER
COMPRESSOR
ST
1
STG.
HEAT
AUX. HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
EM. HEAT
This terminal must be connected to transformer common.
!
# Leave factory-installed jumper in place.
Existing
thermostat
wiring
1
C X
R R
Y Y1
W2 W2
W1
or
G G
O O
L L
F
or
E E
thermostat
wiring
New
1
2
W1
B
15
FRIEDRICH
Wiring
terminal
function
COMMON
POWER
COMPRESSOR
ST
1
STG.
HEAT
AUX. HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
EM. HEAT
This terminal must be connected to transformer common.
!
# Leave factory-installed jumper in place.
$ Tape off the end of the wire. Jumper is not required on this
thermostat (CT70).
Existing
thermostat
wiring
or
RH
Y2
O
E
W3
1
C
X1X
or
RC
or
Y Y1
or
W1
W2 W2
G G
B B
Y1 O
or
L L
X2
or
U
or
3
New
thermostat
wiring
X
R
W1
E
1
2
16
HEIL QUAKER/WHIRLPOOL/TEMPSTAR
Wiring
terminal
function
COMMON
POWER
COMPRESSOR
ST
1
STG.
HEAT
AUX. HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
EM. HEAT
This terminal must be connected to transformer common.
!
# Leave factory-installed jumper in place.
Existing
thermostat
wiring
B
C
or
R R
Y Y1
W W2
G G
B B
O O
X E
thermostat
wiring
New
W1
1
X
2
L
17
LENNOX
Wiring
terminal
function
COMMON
POWER
ST
1
STG.
HEAT (COMP)
ST
1
STG.
COOL
ND
STG.
2
HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
EM. HEAT
This terminal must be connected to transformer common.
!
# Leave factory-installed jumper in place.
Existing
thermostat
wiring
X
Y
or
BL
V/VR
or
M W1
R
R
or
Y W2
O
or
F
Y
or
R O
BK
or
E E
thermostat
wiring
18
New
Y1
1
X
R
2
G
B
L
RHEEM/RUUD
Wiring
terminal
function
COMMON
POWER
COMPRESSOR
ST
1
STG.
HEAT
AUX. HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
EM. HEAT
! This terminal must be connected to transformer common.
# Leave factory-installed jumper in place.
Existing
thermostat
wiring
1
X X
R R
Y Y1
W2 W2
G G
B B
O O
L L
E E
New
thermostat
wiring
W1
1
2
19
TRANE/AMERICAN STANDARD
Wiring
terminal
function
COMMON
POWER
ST
1
STG.
HEAT
AUX. HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
OUTDOOR
SENSOR
OUTDOOR
STAT
This terminal must be connected to transformer common.
!
# Leave factory-installed jumper in place.
$ Tape off end. CT70 replaces outdoor reset with improved zero
droop performance.
Existing
thermostat
wiring
1
B X
R R
Y Y1
W1
W
or
G G
O O
F
L L
or
T
X2 E
W2
or
New
thermostat
wiring
W1
W2
B
3
1
2
20
YORK/BORG WARNER/LUXAIRE (MONCRIEF, FRASER-JOHNSTON)
Wiring
terminal
function
COMMON
POWER
COMPRESSOR
ST
1
STG.
HEAT
AUX. HEAT
FAN
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
EM. HEAT
MULTIPLE AUX.
HEAT LOADS
! This terminal must be connected to transformer common.
# Connect multiple second stage heating loads to W2 terminals.
$ Leave factory-installed jumper in place.
Existing
thermostat
wiring
B
X
or
Y Y1
W
W2 W2
or
G G
H B
O O
4
X
L
or
4
E E
4
W3
New
thermostat
wiring
X
RR
W1
L
2
1
3
% If present on original equipment.
21
YORK/BORG WARNER
Wiring
terminal
function
COMMON
POWER
ST
1
STG.
HEAT
AUX. HEAT
FAN
ST
1
STG.
COOL
C/O VALVE
HEAT
C/O VALVE
COOL
SYSTEM
MONITOR
EM. HEAT
! This terminal must be connected to transformer common.
# Remove factory-installed jumper.
Existing
thermostat
wiring
B
X2 X
or
R R
W1 W1
W2 W2
G G
Y1 Y1
E E
New
thermostat
wiring
B
O
L
1
2
22
23
Automation and Control Solutions
Honeywell International Inc.
1985 Douglas Drive North
Golden Valley, MN 55422
69-0866—2 C.H. Rev. 01-95 www.honeywell.com/yourhome
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