Installation Instructions for
Heating & Air Conditioning
1F73
Non- Programmable, Auto Changeover
Multi-stage/Heat Pump Thermostat
CONTENTS
Preparations .................................................. 1
Thermostat Details ........................................ 1
Removing Old Thermostat ......................... 1-2
Mounting and Wiring .................................. 2-4
Check Thermostat Operation .....................5-6
Specifications ................................................ 6
Operation ...................................................... 6
Troubleshooting ......................................... 7-8
YOUR THERMOSTAT REPLACES
Description 1F73
Heat Pump (No Aux or Emergency Heat) Yes*
Heat Pump (with Aux or Emergency Heat) Yes*
Standard Heat & Cooling Systems Yes*
Two Stage Heat & Two Stage Cool Yes*
Standard Heat Only Systems Yes*
Millivolt Heat Only Systems – Floor or Wall Furnaces No
Standard Central Air Conditioning Yes*
Gas or Oil Heat Yes*
Electric Furnace Yes*
Hydronic (Hot Water) Zone Heat – 2 Wires Yes*
Hydronic (Hot Water) Zone Heat – 3 Wires No
* Requires common for 24 VAC at the thermostat
THERMOSTAT DETAILS
2
O/B Terminal
Switches Selection
B
O
Mounting
Hole
(O/B)Y2 E/W1 R
L
GASELEC
Elec – Gas
Switch
Figure 1. Thermostat Base
C
Y1
G
W2
Mounting
Hole
PREPARATIONS
1
Assemble tools required as shown below.
HAND OR POWER
DRILL WITH 3/16 INCH
DRILL BIT, IF NEEDED
FLAT BLADE SCREWDRIVER
SPIRIT LEVEL OR PLUMB BOB AND LINE OPTIONAL—
THERMOSTAT DOES NOT NEED TO BE LEVEL TO WORK PROPERLY
WIRE CUTTER/STRIPPER
Failure to follow and read all instructions carefully
before installing or operating this control could cause
personal injury and/or property damage.
REMOVING OLD THERMOSTAT
3
CAUTION
!
To prevent electrical shock and/or equipment damage,
disconnect electrical power to the system at the main
fuse or circuit breaker until installation is complete.
Before removing wires from old thermostat’s switching subbase,
label each wire with the terminal designation it was removed from.
1. Remove Old Thermostat: A standard heat/cool thermostat
consists of three basic parts:
a. The cover, which may be either a snap-on or hinge type.
b. The base, which is removed by loosening all captive screws.
c. The switching subbase, which is removed by unscrewing
the mounting screws that hold it on the wall or adaptor plate.
2. Shut off electricity at the main fuse box until installation is
complete. Ensure that electrical power is disconnected.
3. Remove the front cover of the old thermostat. With wires still
attached, remove wall plate from the wall. If the old thermostat
has a wall mounting plate, remove the thermostat and the wall
mounting plate as an assembly.
4. Identify each wire attached to the old thermostat.
5. Disconnect the wires from the old thermostat one at a time. DO
NOT LET WIRES FALL BACK INTO THE WALL.
6. Install new thermostat using the following procedures.
White-Rodgers is a division
of Emerson Electric Co.
www.white-rodgers.com
PART NO. 37-6489B
Replaces 37-6489A
0621
REMOVING OLD THERMOSTAT
3
CONTINUED FROM PAGE 1
ATTENTION! This product does not contain mercury. How-
ever, this product may replace a unit which contains mercury.
Do not open mercury cells. If a cell becomes damaged, do not
touch any spilled mercury. Wearing non-absorbent gloves, take
up the spilled mercury and place into a container which can be
sealed. If a cell becomes damaged, the unit should be discarded.
Mercury must not be discarded in household trash. When the unit
this product is replacing is to be discarded, place in a suitable
container and return to White-Rodgers at 2895 Harrison Street,
Batesville, AR 72501 for proper disposal.
MOUNTING AND WIRING
4
WARNING
!
Do not use on circuits exceeding specified voltage.
Higher voltage will damage control and could cause
shock or fire hazard.
Do not short out terminals on gas valve or primary
control to test. Short or incorrect wiring will damage
thermostat and could cause personal injury and/or property damage.
Thermostat installation and all components of the system shall conform to Class II circuits per the NEC code.
CAUTION
!
Take care when securing and routing wires so they do
not short to adjacent terminals or rear of thermostat.
Personal injury and/or property damage may occur.
Attach Thermostat Base to Wall
1. Remove the packing material from the thermostat. Gently pull
the cover straight off the base. Forcing or prying on the
thermostat will cause damage to the unit.
2. Connect wires beneath terminal screws on base using appropriate wiring schematic (see figs. 2 through 4).
3. Place base over hole in wall and mark mounting hole locations
on wall using base as a template.
4. Move base out of the way. Drill mounting holes.
5. Fasten base loosely to wall, as shown in fig. 1, using two
mounting screws. Place a level against bottom of base, adjust
until level, and then tighten screws. (Leveling is for appearance only and will not affect thermostat operation.) If you are
using existing mounting holes, or if holes drilled are too large
and do not allow you to tighten base snugly, use plastic screw
anchors to secure subbase.
6. Push excess wire into wall and plug hole with a fire-resistant
material (such as fiberglass insulation) to prevent drafts from
affecting thermostat operation.
Electric/Gas Switch (Fan Option)
The ELEC/GAS switch is factory set to the GAS position. In this
position, the thermostat will not power the circulator fan on a call
for heat.
If your system requires that the thermostat power the circulator
fan this switch must be set to the ELEC position. On a multi-stage
system, the thermostat will power the circulator fan on a call for
heat. On a Heat Pump system, the thermostat will power the
circulator fan on a call for second stage heat when the thermostat
is in Emergency mode.
O/B Terminal Switch Selection
The O/B switch on this thermostat is factory set to “O” position.
This will accommodate the majority of heat pump applications,
which require the changeover relay to be energized in COOL. If
the thermostat you are replacing or the heat pump being installed
with this thermostat requires a “B” terminal, to energize the
changeover relay in HEAT, the O/B switch must be moved to the
“B” position.
For multi-stage, the switch must be in “O” position for “Y2” to
operate properly.
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MOUNTING AND WIRING
4
CONTINUED FROM PAGE 2
See Note **
Emergency
E/W1
Relay
CY1
L
SYSTEM
MONITOR
SWITCH
24 VAC
(Class II Current Limited)
THERMOSTAT
R
SYSTEM
120 VAC
TRANSFORMER
Hot
Neutral
O/B/Y2
G W2
Changeover
Relay*
Compressor
Contactor
* Changeover Relay is energized in COOL when O/B switch is in the “O” position
Changeover Relay is energized in HEAT when O/B switch is in the “B” position
** Jumper required to use a single Aux Heat for both Second Stage Heat and Emergency
Fan
Relay
Aux
Relay
(Stage 2)
Figure 2. Typical wiring diagram for single transformer heat pump systems
If safety circuits are in only one of the systems, remove
the transformer of the system with NO safety circuits.
O/B/Y2
CUT AND
TAPE OFF!
HOT
120 VAC
NEUTRAL
* Changeover Relay is energized in COOL when O/B switch is in the “O” position
Changeover Relay is energized in HEAT when O/B switch is in the “B” position
** Jumper required to use a single Aux Heat for both Second Stage Heat and Emergency
24 VAC
Changeover
Relay*
Compressor
Contactor
G W2
Fan
Relay
NOTE
See Note **
Emergency
Aux
Relay
(Stage 2)
Relay
TWO COMMONS MUST
BE JUMPERED TOGETHER!
E/W1
CY1
SYSTEM
MONITOR
SWITCH
L
THERMOSTAT
R
SYSTEM
Limit or
Safety
Switches
24 VAC
TRANSFORMER
(Class II Current Limited)
Figure 3. Typical wiring diagram for two transformer heat pump systems with NO safety circuits
Hot
120 VAC
Neutral
CY1
SYSTEM
MONITOR
SWITCH
NOTE
L
COMMON
R
Switches
Limit or
Safety
Switches
THERMOSTAT
Limit or
Safety
24 VAC
24 VAC
ACCESSORY
RELAY N.O.
CONTACT
COMMON
Current Limited)
24 VAC 120 VAC
Heat Pump Transformer
(Class II Current Limited)
SYSTEM
Auxiliary
Heating
Transformer
(Class II
Limit or
Safety
Switches
120 VAC
The accessory relay scheme
is required when safety
circuits exist in both systems.
Limit or
Safety
Switches
NEUTRAL
NOTE
HOT
NEUTRAL
Polarity must be observed. If the HOT side of the second transformer
is jumpered to the COMMON side of the first transformer a short will
be made. Damage to equipment will occur when power is restored.
O/B/Y2
Changeover
Relay*
Compressor
Contactor
* Changeover Relay is energized in COOL when O/B switch is in the “O” position
Changeover Relay is energized in HEAT when O/B switch is in the “B” position
** Jumper required to use a single Aux Heat for both Second Stage Heat and Emergency
G W2
Fan
Relay
Aux
Relay
(Stage 2)
E/W1
See Note **
Emergency
Relay
TWO COMMONS MUST
BE JUMPERED TOGETHER!
Figure 4. Typical wiring diagram for two transformer heat pump systems with safety circuits in BOTH systems
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HOT