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HOT GAS REHEAT CONTROL — Units with hot gas re-
heat (HGRH) will include an additional H terminal on the im-
put terminal board for dehumidification control. To enable a
call for dehumidification, a 24V signal must be sent to the H
terminal with no voltage applied to the Y1 or O terminals. Any
call for cooling (Y1 and O) will override the dehumidification
call.
Unit heat pumps are supplied with a 50 VA control trans-
former as standard. Models with WSHP Open, Deluxe D con-
trol package, hot gas reheat (HGRH), or waterside economizer
options are supplied with a 75VA transformer. The VA ca-
pacity of the transformer should be considered when connect-
ing low voltage accessories to the heat pump such as thermo-
stats or solenoid valves. Table 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 any at-
tached accessories must be lower than the VA capacity of the
unit control transformer.
Step 9 — Wire Field Controls
SAFETY DEVICES AND UNIT PROTECTION MOD-
ULE (UPM) — Each unit is factory provided with a UPM
board that controls the compressor operation and monitors the
safety. See Fig. 20.
If the unit is being connected to a thermostat with a mal-
function light, this connection is made at the unit malfunction
output or relay. See Table 9 for UPM board fault blink codes.
Fig. 20 — Unit Protection Module (UPM)
Table 8 — Low Voltage VA Draw
IMPORTANT: Exceptionally long runs of thermostat wire
should be avoided to prevent voltage drops in the control
circuit.
CAUTION
Exceeding the transformer capacity can result in low con-
trol voltage, erratic unit operation or damage to the heat
pump.
WARNING
To avoid possible injury or death due to electrical shock,
open the power supply disconnect switch and secure it in
an open position during installation.
1
2
3
4
5
6
7
9
10
11
12
13
17
14
15
16
8
1
Board Power Indicator
2
UPM Status LED Indicator
3
Water Coil Freeze Protection Temperature Selection [R30]
4
Air Coil Freeze Protection Temperature Selection
5
UPM Settings
6
Water Coil Freeze Connection
7
Air Coil Freeze Connection
8
LED Status-Diagnostic Connection
9
24VAC Power Input
10
Compressor Contact Output
11
High Pressure Switch Connection
12
Call for Compressor Y1
13
Low Pressure Switch Connection
14
24VAC Power Common
15
Condensate Overflow Sensor
16
Dry Contact
17
UPM Ground Standoff
STANDARD CONSTRUCTION
HOT GAS REHEAT OR ECONOMIZER
OPTIONAL COMPONENTS
Component
VA
Component
VA
Component
VA
Blower Relay (PSC
motors only)
6-7
Total from ‘Standard’
22-26
Monitor Relay (VA draw
per relay)
6-7
Reversing Valve
Solenoid
8-9
Additional Control
Relays
12-14
Internal 2 Way
Motorized Valve
7
Compressor Contactor
6-8
Hot Gas Reheat
Solenoid
8-9
Complete C board
2
—
—
Total VA draw
22-26
Total VA draw
42-49