2
1. Turn off all power to unit.
2. If an existing thermostat is being replaced:
a. Remove existing thermostat from the wall.
b. Disconnect wires from existing thermostat. Do not
allow wires to fall back into the wall. As each wire
is disconnected, record wire color and terminal
connection.
c. Discard or recycle old thermostat.
NOTE: Mercury is a hazardous waste and must be
disposed of properly.
3. Remove the thermostat cover from wall plate (mounting
base) to expose mounting holes. See Fig. 1. With the ther-
mostat facing forward, press the back plate on the left
hand side top corner to release the two prongs holding on
the cover. Pull off the cover when the prongs have been
disengaged.
4. Route thermostat wires through large hole in mounting
base. Remove outer sheath from wires for added flexibili-
ty. Standard solid or multi-conductor thermostat wire
should be used from the thermostat to the unit. Size and
length considerations are as follows: for a maximum dis-
tance from unit of 36 ft, use 22 AWG (American Wire
Gage) wire; for a maximum distance from unit of 100 ft,
use 18 AWG wire.
5. Level mounting base against wall and mark wall through
the 2 mounting holes in base.
6. Drill two
3
/
16
-in. mounting holes in wall where marked.
7. Secure mounting base to wall with 2 screws and anchors
provided. Ensure all wires exit through hole in mounting
base.
8. Adjust wire length and routing to allow proper closure of
the thermostat. Strip each wire at the end no more than
1
/
4
-in. to prevent adjacent wires from shorting together.
Match and connect wires to terminals on the thermostat.
See Fig. 2-4 and Table 1.
9. Push excess wiring into wall. Seal hole in wall to prevent
drafts.
10. Re-attach thermostat cover to back plate by aligning the
top two prongs of the back plate in the vertical groove of
the top cover and then snapping the cover onto the back
plate.
11. Turn on power to unit. The thermostat will receive power
from the unit. The thermostat will be powered by 24 v,
nominal (18 to 30 vac). Terminals R (+ 24 v), W1/O/B
(first stage heat or reversing valve), Y1 (first stage cool-
ing), and G (fan relay) will always be connected. Some
applications will use C (common), Y2 (second stage
cooling), or W2 (second stage heating).
Be careful not to drill into wiring in wall. Electrical shock
could result.
Improper wiring or installation may cause damage to the
thermostat. Check to ensure wiring is correct before pro-
ceeding with installation of unit.
Fig. 1 — Thermostat Mounting
LEGEND
W2 — Second-Stage Heat
Y2 — Second-Stage
Compressor
RS2 — Second Remote
Sensor (Not Used)
RS+5 — +5 vdc
RS1 — Remote Sensor
RS GND — Ground
W1/O/B — First-Stage Heat or
Reversing Valve
Y1 — First-Stage Compressor
G—Fan
W3/ECO — Economizer
CK1 — Dry Contact
CK2 — Dry Contact Ground
R—24 vac Transformer
C—24 vac Transformer
Common
→ Fig. 2 — Thermostat Wiring
1204
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