QV Series Heat Pumps
QV Series Heat Pumps
8733829041 (2021/07)
16
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Electrical—Low-Voltage Wiring
Subject to change without prior notice
thermostats on an interior wall away from supply
ducts.
Avoid external walls and locations subject to direct
sunlight and drafts. Thermostat wiring must be
18AWG (American Wire Gauge). Refer to the
installation instructions of the thermostats for
further details.
Refer to the installation instructions for the
thermostat for further details.
Table 1 Thermostat Connections Options
VA Capacity
Unit heat pumps are supplied with a 50VA control
transformer as a standard. Models with DDC, hot
gas reheat or an economizer are supplied with a 75
VA transformer. The 75 VA and 100 VA
transformers are available as optional components
for most models (size 018 and larger for 100 VA).
The VA capacity of the transformer must be
considered when connecting low-voltage
accessories to the heat pump such as thermostats
or solenoid valves. Table 2 shows the VA draw of
factory-mounted components in the low-voltage
heat pump. The total VA draw of the heat pump
internal components plus attached accessories
must be lower than the VA capacity of the unit
control transformer.
Table 2 Low-Voltage VA Draw —Standard Construction, Hot Gas
Reheat or Economizer, and Optional Components
Thermostat to HVAC Equipment Wiring
The thermostat may not function properly if the
total resistance of any of the thermostat to HVAC
equipment wires exceeds 2.5 ohms. To ensure that
wire length does not cause excess resistance, refer
to Table 3 and ensure that the wires from the
thermostat to the HVAC equipment are not too
long.
NOTICE:
To prevent voltage drops in the
control circuit, do not exceed the
recommended thermostat wire lengths
detailed in Table 3.
Connection
Function
Y1
First-Stage Compressor Operation
G
Fan
O
Reversing Valve (energized in
cooling)
W1
Auxiliary Electric Heat (runs in
conjunction with compressor)
NC
Transformer 24 VAC Common
(extra
connection)
C1
Transformer 24 VAC Common
(primary
connection)
R
Transformer 24 VAC Hot
H
Dehumidification Mode
WARNING:
Exceeding the transformer
capacity will result in low control voltage,
erratic unit operation, or damage to the
heat pump.
Standard Construction
Optional Components
Component
VA
Component
VA
Reversing Valve Solenoid
8–9
Monitor Relay (VA draw
per relay)
6–7
Compressor Contactor
6-8
Internal
Two-Way
Motorized Valve
7
UPM Board
2
LED Annunciator
1
Total VA Draw
22–26