Honeywell THP9045A User manual

Wire Saver Installation
Wire Saver THP9045A
(Optional – for thermostats
without 24-volt C wire)

2
A wire saver acts as a splitter for
applications that do not include a
24-volt C wire. If your heating/cooling
system does not include a C wire,
install the wire saver in or near the
main unit (furnace, air handler) of
your heating/cooling system.
What tools do I need to install it?
• Small, flat screwdriver
• Two-sided mounting tape (included)
• Thermostat wire bundle, ends
stripped (included)
About the Wire Saver
Before you begin installation, view the video at http://hwll.co/wiresaver
THERMOSTAT
WIRE SAVER
HEATING/COOLING
SYSTEM

3
Complete Steps 1.1 through 1.6 in the Quick
Start Guide.
• Identify existing wires and verify that there
is no C wire (Quick Start Guide Step 1.2).
If you have a C wire, you do not need to
install the wire saver.
• If your old thermostat has no C wire connector but the wire bundle from your heating/
cooling system includes an extra wire not connected to the old thermostat, you can use
that wire to connect your Wi-Fi thermostat’s C terminal. You do not need to use the wire
saver. Refer to the Alternate Wiring video at wifithermostat.com/videos
Take a photo of the wire connections (Quick Start Guide Step 1.2) or make notes
to carry to your heating/cooling system.
Step 1 Verify that you need a wire saver
Quick Start Guide
Wi-Fi Programmable
Thermostat
RTH6500WF Wi-Fi Series
Important! Ensure that the system is OFF
(Quick Start Guide Step 1.1)

4
At your new thermostat, for each wire:
1. Loosen the screw, insert wire on inside edge
of thermostat terminal, then tighten screw.
2. Verify wire is firmly secured by gently
pulling on wire.
3. Repeat steps 1 and 2 for all wires.
a. Match the wires labeled R and W to
the R and W terminals.
b. Match the wire labeled Y to the C
terminal.
c. Match the wire labeled G to the K
terminal.
4. Push any excess wire back into the wall
opening after all wires are installed.
Note: The wiring for your application might be different from the wiring shown here.
Step 2 Wire the thermostat
Remove metal jumper
only if you have both R
and Rc wires
MCR35231
W2 GW YR RcKY2 C
Y
HEAT PUMP
CONVENTIONAL
AUX/E
GO/B YRRcKLC
G
W
R

5
Mount the wire saver to a surface near the terminal block for the heating/cooling system.
a. Locate the terminal block in your heating/cooling
system to which the thermostat wires are attached.
You may need to open or remove the front
panel/door. If you are unsure how to do this,
refer to your heating/cooling system
documentation.
b. Peel paper from one side of the included two-
sided mounting tape.
c. Attach the sticky side to a suitable surface
(such as the furnace wall or floor) that is close
enough to the terminal block for the shortest
wire to reach the wire saver.
d. Peel the paper from the outer surface of the
mounting tape and attach the wire saver with
the terminal block labeled THERMOSTAT at the top.
Step 3 Mount the wire saver
M35224
Rc K C W-O/B
Rc Y G C W-O/B
THP9045A 1023
1326
http://yourhome.honeywell.com
1-800-546-1502
EQUIPMENT
THERMOSTAT
Two-sided mounting tape

6
Step 4 Select a wire configuration
Examine the labels on the terminal block for the existing thermostat wires.
Determine which of the following combinations matches your setup:
a. Single stage system (1 heat and 1 cooling stage) uses wires R or Rc, Y, G, W
b. Two stage heat, single stage cooling system uses wires R or Rc, Y, G, W, W2
c. Two stages for each heating and cooling uses wires R or Rc, Y, Y2 G, W, W2
If none of these combinations matches what you see, call customer service for further
instructions.

7
Step 5 Connect the wire saver
Connecting the wire saver involves two main actions: moving some wire connections
from the terminal block in your heating/cooling system to the THERMOSTAT terminal block
of the wire saver and using the included wire bundle to connect the terminal block on the
equipment to the EQUIPMENT block on the wire saver.
To connect the wire saver, follow the instructions and diagram for your setup as
determined in Step 4.
• Follow instructions under 5a if you have a single stage setup.
.
• Follow instructions under 5b if you have two-stage heat, single-stage cooling.
• Follow instructions under 5c if you have two-stage heating and cooling.

8
5a Wire single-stage equipment
1. Disconnect the R wire from your heating/cooling system’s terminal block.
2. Connect the R wire to the Rc terminal on the THERMOSTAT end of the wire saver.
3. Disconnect the W wire from the heating/cooling system; connect it to W on the
THERMOSTAT end of the wire saver.
4. Disconnect the G wire; connect it to K on the THERMOSTAT end of the wire saver.
5. Disconnect the Y wire; connect it to C on the THERMOSTAT end of the wire saver.
6. Connect stripped ends of the included wire bundle to the terminals labeled EQUIPMENT
on the wire saver in this color order:
a. Connect red to Rc
b. Connect yellow to Y
c. Connect green to G
d. Connect blue to C
e. Connect white to W
7. Connect the other set of stripped ends to the terminals on your heating/cooling system
following the same color order.

9
Wiring diagram: Single-stage equipment
When you complete the steps above,
your wire saver and heating/cooling
system will be wired as shown.
Rc K C W-O/B
Rc Y G C W-O/B
THP9045A 1023
1326
http://yourhome.honeywell.com
1-800-546-1502
EQUIPMENT
THERMOSTAT
WIRE BUNDLE
Wire
Saver
M35229
R Y W G C O/B
At Heating/
Cooling System
To Thermostat

10
5b Wire two-stage heat, single-stage cooling
1. Do not disconnect the W2 wire from your heating/cooling system.
2. Disconnect the R wire from your heating/cooling system’s terminal block.
3. Connect the R wire to the Rc terminal on the THERMOSTAT end of the wire saver.
4. Disconnect the W wire from the heating/cooling system; connect it to W on the
THERMOSTAT end of the wire saver.
5. Disconnect the G wire; connect it to K on the THERMOSTAT end of the wire saver.
6. Disconnect the Y wire; connect it to C on the THERMOSTAT end of the wire saver.
7. Connect stripped ends of the included wire bundle to the terminals labeled EQUIPMENT
on the wire saver in this color order:
a. Connect red to Rc
b. Connect yellow to Y
c. Connect green to G
d. Connect blue to C
e. Connect white to W
8. Connect the other set of stripped ends to the terminals on your heating/cooling system
following the same color order.

11
Wiring diagram: Two-stage heat, single-stage cooling
When you complete the steps in 5b,
your wire saver and heating/cooling
system will be wired as shown.
Rc K C W-O/B
Rc Y G C W-O/B
THP9045A 1023
1326
http://yourhome.honeywell.com
1-800-546-1502
EQUIPMENT
THERMOSTAT
WIRE BUNDLE
Wire
Saver
M35226
W2 R Y W G C O/B
At Heating/
Cooling System
To Thermostat
To Thermostat

12
5c Wire two-stage heat, two-stage cooling
1. Do not disconnect the W2 or Y2 wires from your heating/cooling system.
2. Disconnect the R wire from your heating/cooling system’s terminal block.
3. Connect the R wire to the Rc terminal on the THERMOSTAT end of the wire saver.
4. Disconnect the W wire from the heating/cooling system; connect it to W on the
THERMOSTAT end of the wire saver.
5. Disconnect the G wire; connect it to K on the THERMOSTAT end of the wire saver.
6. Disconnect the Y wire; connect it to C on the THERMOSTAT end of the wire saver.
7. Connect stripped ends of the included wire bundle to the terminals labeled EQUIPMENT
on the wire saver in this color order:
a. Connect red to Rc
b. Connect yellow to Y
c. Connect green to G
d. Connect blue to C
e. Connect white to W
8. Connect the other set of stripped ends to the terminals on your heating/cooling system
following the same color order.

13
Wiring diagram: Two-stage heat, two-stage cooling
When you complete the steps in 5c,
your wire saver and heating/cooling
system will be wired as shown.
Rc K C W-O/B
Rc Y G C W-O/B
THP9045A 1023
1326
http://yourhome.honeywell.com
1-800-546-1502
EQUIPMENT
THERMOSTAT
WIRE BUNDLE
Wire
Saver
M35227
W2 R Y W G C O/B
Y2
At Heating/
Cooling System
To Thermostat
To Thermostat

14
Example wire saver setup: before and after
The instructions are for changing wiring at your main heating/cooling system. These
images show the relationships between your thermostat and heating/cooling system
before and after installing the wire saver.
Rc K C W-O/B
Rc Y G C W-O/B
THP9045A 1023
1326 http://yourhome.honeywell.com
1-800-546-1502
EQUIPMENT
THERMOSTAT
W2 GW YRRcK Y2 C
Y
HEAT PUMP
CONVENTIONAL
AUX/E GO/B YRRcK LC
G
W
R
M35225
R Y W G C O/B
WIRE BUNDLE
Wire
Saver
At Thermostat
At Heating/
Cooling System
W2 GW YRRcK Y2 C
HEAT PUMP
CONVENTIONAL
AUX/E
GO/B YRRcK LC
M35228
R Y W G C O/B
Y
G
W
R
At Heating/
Cooling System
At Thermostat
BEFORE
AFTER

15
Step 6 Close the equipment door
Close or put back door to the heating and cooling system so the interlock switch will allow
the system to be turned on for the heating/cooling system and thermostat display. Your
thermostat display will not turn on if the door/panel is not closed.
Step 7 Follow instructions in Quick Start Guide
Continue with Step 1.8 in the Quick Start Guide.

Automation and Control Solutions
Honeywell International Inc.
1985 Douglas Drive North
Golden Valley, MN 55422
wifithermostat.com
® U.S. Registered Trademark.
© 2014 Honeywell International Inc.
33-00042—02 M.S. 06-14
Printed in U.S.A.
33-00042-01