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W A T E R - S O U R C E H E A T P U M P S
JRE - Series
R e v . : A u g u s t 1 9 , 2 0 2 0
Electrical – Low Voltage Wiring
Thermostat Connections - The thermostat will be wired
to the DXM2 board located within the unit control box.
Refer to the unit wiring diagram for specific details.
Low Water Temperature Cutout Selection - The DXM2
control allows the field selection of low water (or water-
antifreeze solution) temperature limit by clipping jumper
JW3, which changes the sensing temperature associated
with thermistor LT1. Note that the LT1 thermistor is
located on the refrigeravnt line between the coaxial heat
exchanger and expansion device (TXV). Therefore, LT1 is
sensing refrigerant temperature, not water temperature,
which is a better indication of how water flow rate/
temperature is affecting the refrigeration circuit.
The factory setting for LT1 is for systems using water
(30°F [-1.1°C] refrigerant temperature). In low water
temperature (extended range) applications with antifreeze
(most ground loops), jumper JW3 should be clipped as
shown in Figure 3 to change the setting to 10°F [-12.2°C]
refrigerant temperature, a more suitable temperature
when using an antifreeze solution. All Johnson Controls
WSHP units operating with entering water temperatures
below 60°F [15.6°C] must include the optional water/
refrigerant circuit insulation package to prevent internal
condensation.
16
Y2
W
O
G
R
C
AL1
P2
AL2
R
NSB
JW1
Alarm
Relay
C
ESD
7"
OVR
H
A
P3
R
NO1
NC1
Acc1
Relay
COM
NO2
NC2
Acc2
COM
Relay
R
AO1 Gnd
I n s t a l l a t i o n , O p e r a t i o n , M a i n t e n a n c e
Com
Fan Enable
Micro
U1
Figure 3: LT1 Limit Setting
Fault
Status
Off
On
Off
On
S3
Off
On
S2
A0-1 A0-2
S1
P10
P11
T1
T2 T2 T3 T3 T4 T4
Gnd
AO2
5 1/2"
JW3-LT1 jumper should be clipped for low temperature
Note: There is only
(antifreeze) operation
one T1 connection
Accessory Connections - A terminal paralleling the
compressor contactor coil has been provided on the
DXM2 control. Terminal "A" is designed to control
accessory devices. Note: This terminal should be used
only with 24 Volt signals and not line voltage. Terminal "A"
is energized with the compressor contactor.
The DXM2 controller includes two accessory relays ACC1
and ACC2. Each relay includes a normally open (NO) and
a normally closed (NC) contact. Accessory relays may be
configured to operate as shown in the tables below.
N.O.
Fan Speed
P8
Test
12V
P12
IN
1
OUT
Gnd
NC
1
HP
HP
LP
LP
LT1
LT1
LT2
LT2
RV
RV
CO
JW3
12
CO
P7
RV
Relay
CCH
1
24Vdc
Relay
EH1
4
EH2
P6
Comp
Relay
CCG
CC
P9
T5
T5 T6 T6
DXM2 PCB
Use 4 mounting screws
#6 sheet metal screw 1" long
6 1/2"
Factory low
voltage Molex
connection fo
unit harness
Factory low
voltage Molex
connection for
electric heat
harness
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