Installation Instructions; Remove And Replace The Old Thermostat; Wire Connections - Daikin TSTATD4271C Installation And Maintenance Manual

Installation Instructions

Remove and Replace the Old Thermostat

To install the thermostat properly, please follow these step by
step instructions. If you are unsure about any of these steps,
call a qualified technician for assistance.
• Assemble tools: Flat blade screwdriver, wire cutters and
wire strippers.
• Make sure your Heater/Air Conditioner is working
properly before beginning installation of the thermostat.
• Carefully unpack the thermostat. Save the screws, any
brackets, and instructions.
• Turn off the power to the Heating/Air Conditioning system
at the main fuse panel. Most residential systems have a
separate breaker for disconnecting power to the furnace.
• Remove the cover of the old thermostat. If it does not
come off easily, check for screws.
• Loosen the screws holding the thermostat base or
subbase to the wall and lift away.
• Disconnect the wires from the old thermostat. Tape the
ends of the wires as you disconnect them, and mark them
with the letter of the terminal for easy reconnection to the
new thermostat.
• Keep the old thermostat for reference purposes, until your
new thermostat is functioning properly.

Wire Connections

If the terminal designations on your old thermostat do not
match those on the new thermostat, refer to the chart below or
the wiring diagrams that follow.
Table 1: Terminal Designations
Wire from the
old thermostat
terminal marked
G or F
Y1, Y or C
W1, W or H
Rh, R, M, Vr, A
C
O/B
W2 2nd Stage Heat
Y2 2nd Stage Heat
W3 3rd Stage Cooling
Ck1 Dry Contact Switch
CKGND Dry Contact Switch
S1, OUT - Outdoor Sensor
S2, OUT + Outdoor Sensor
* O/B is used if your system is a Heat Pump
IM 1227 • MODELS DC THERMOSTATS
Install on the
Function new thermostat
connector marked
Fan G
Cooling Y1
Heating W1/0/B
Power R
Common C
Rev. Valve W1/O/B*
W2
Y2
W3
DRY CONTACT
DRY CONTACT
OUTDOOR
OUTDOOR
7-D P C
ay rogrammable
Figure 6: TSTATD4271C Thermostat Backplate
W1/O/B
W2
W3
C
R
OUTDOOR SENSOR
DRY CONTACT
Y2
Y1
G
IMPORTANT: This thermostat requires both R (24 VAC Return)and C (24 VAC
Common) be connected to the backplate terminals.
6
D T
ommerCial igiTal hermosTaTs
1st stage heat/reversing valve
2nd stage heat circuit
3rd stage heat circuit
24 VAC common
24 VAC Return
Outdoor Sensor connections
Dry Contact connections
2nd stage compressor
1st stage compressor
Fan relay
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