Wiring; Wiring Diagrams - Pro1 Technologies T855iSH Installation Manual

Wiring

Caution:
Electrical Hazard
Failure to disconnect the power
before beginning to install this
product can cause electrical shock
or equipment damage.
Wiring
1.
If you are replacing a thermostat,
make note of the terminal
connections on the thermostat that
is being replaced. In some cases
the wiring connections will not be
color coded. For example, the
green wire may not be connected
to the G terminal.
2.
Loosen the terminal block screws.
Insert wires then retighten the
terminal block screws.
3. Place nonflammable insulation into
the wall opening to prevent drafts.
Wiring Tips
C Terminal
This thermostat requires a 24V
common wire to the C terminal.
Wire Specifications
Use shielded or non-shielded 18-22
gauge thermostat wire.
Note:
Outdoor temperature sensor, Indoor temperature sensors, and Slab sensor
wiring diagrams are located in R250S and R251S manuals.
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Wiring Diagrams

Power supply
Factory-installed jumper. Remove only when installing on 2-transformer systems
Typical 2H/2C System: 1 Transformer
RC
RH
COMPRESSOR
Y
RELAY
C
W/E
HEAT RELAY
G
FAN RELAY
W2
Y2
HEAT RELAY 2
COMPRESSOR
RELAY 2
Typical Heat Only System With Fan
RC
RH
Y
C
W/E
HEAT RELAY
G
FAN RELAY
Note:
In many systems with no emergency heat relay a jumper can be installed
between E and W2.
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Warning:
All components of the control
system and the thermostat
installation must conform to
Class II circuits per the NEC Code.
Installation Tip
Do not overtighten terminal
block screws, as this can
damage the terminal block.
A damaged terminal block
can keep the thermostat
from fitting on the subbase
correctly or cause system
operation issues.
Max Torque = 6in-lbs.
Note:
In many heat pump systems with
no emergency heat relay, a jumper
can be installed between E and
W2 to turn thermostat into a single
stage control for Emergency Heat
Operation.
R
L1
(HOT)
L2
C
Typical Cool-Only System With Fan
RC
RH
COMPRESSOR
Y
RELAY
C
W/E
G
FAN RELAY
R
L1
(HOT)
L2
C
Wiring
Terminal Designations
This thermostat is shipped from the factory to operate a conventional heating
and cooling system. This thermostat may also be configured for a heat pump
system. See the "heat pump" configuration step on page 16 of this manual to
configure the thermostat for heat pump applications.
2 Heat 2 Cool
Conventional
Terminal
Transformer power
RC
Transformer power
RH
C
Reversing valve
B
Reversing valve
O
G
W/E
Y
Y2
W2
S1/S2
Remote Sensor
H
D
Wiring Diagrams
Use either O or B terminals for changeover valve
A 24 VAC common connection is required with this thermostat.
If DEHUM relay requires a normally-energized input, set Dehumidify relay to NC
in Technician Setup.
Typical 2H/2C System: 2 Transformer
REMOVE JUMPER
RC
RH
Y
C
W/E
R
G
L1
(HOT)
W2
L2
Y2
C
Typical 2H/1C Heat Pump System
RC
RH
Y
C
W/E
G
W2
O
B
2 Heat 1 Cool 4 Heat 2 Cool
Heat Pump
System System
Transformer power Transformer power
(cooling) (cooling)
Transformer power Transformer power
(heating) (heating)
Transformer
Transformer
common
common
Reversing valve
/ configurable / configurable
terminal terminal
Reversing valve
/ configurable / configurable
terminal terminal
Fan relay
Fan relay
First stage
Emergency Heat
of heat
First stage
First stage of
of cool
heat & cool
Second stage
N/A
of cool
Second stage of
Second stage
Auxiliary heat
of heat
Remote Sensor
Humidify
Humidify
Dehumidify
Dehumidify
COMPRESSOR
RELAY
HEAT RELAY
FAN RELAY
HEAT RELAY 2
COMPRESSOR
RELAY 2
R
L1
(HOT)
L2
COMPRESSOR
C
RELAY
EMERGENCY
HEAT
FAN RELAY
COOL
CHANGEOVER
VALVE
HEAT
CHANGEOVER
VALVE
5 Heat 3 Cool
Heat Pump Heat Pump
System System
Transformer power
(cooling) (cooling)
Transformer power
(heating) (heating)
Transformer Transformer
common common
Reversing valve /
Reversing valve
/ configurable 3rd stage of heat
terminal & cool
Reversing valve Reversing valve /
/ configurable 3rd stage of heat
terminal & cool
Fan relay Fan relay
First stage of
First stage of
auxiliary heat
auxiliary heat
(4th stage of heat)
First stage of First stage of
heat & cool heat & cool
Second stage Second stage
of heat & cool of heat & cool
Second stage of
auxiliary heat
auxiliary heat
(5th stage of heat)
Remote Sensor Remote Sensor
Humidify Humidify
Dehumidify Dehumidify
10
R
L1
(HOT)
L2
R
C
L1
(HOT)
L2
C
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