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
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
30
Condenser Hot Water Reheat – Sequence of Operation
Table 2: Humidistat/Dehumidistat Logic and DXM2 (2.1, 2.2., 2.3) DIP settings
Sensor
2.1
2.2
2.3
Logic
Reheat (ON)–H
Reheat (OFF)–H
Humidistat
OFF
OFF
OFF
Reverse
0 VAC
24 VAC
Dehumidistat
OFF
ON
OFF
Standard
24 VAC
0 VAC
1
Cooling input takes priority over dehumidify input.
2
DXM2 is programmed to ignore the H demand when the unit is in heating mode.
3
N/A for single stage units; Full load operation for dual capacity units.
4
ON/OFF = Either ON or OFF.
Mode
Input
Output
O
G
Y1
Y2
3
H
O
G
Y1
Y2
3
Reheat
No Demand
ON/OFF
OFF
OFF
OFF
OFF
ON/OFF
OFF
OFF
OFF
OFF
Fan Only
ON/OFF
ON
OFF
OFF
OFF
ON/OFF
ON
OFF
OFF
OFF
Cooling 1st Stage
ON
ON
ON
OFF
OFF
ON
ON
ON
OFF
OFF
Cooling 2nd Stage
ON
ON
ON
ON
OFF
ON
ON
ON
ON
OFF
Cooling & Dehumidistat
1
ON
ON
ON
ON/OFF
ON
ON
ON
ON
ON/OFF
OFF
Dehumidistat Only
ON/OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
Heating 1st Stage
OFF
ON
ON
OFF
OFF
OFF
ON
ON
OFF
OFF
Heating 2nd Stage
OFF
ON
ON
ON
OFF
OFF
ON
ON
ON
OFF
Heating & Dehumidistat
2
OFF
ON
ON
ON/OFF
ON
OFF
ON
ON
ON/OFF
OFF
Table 3: Condenser Hot Water Reheat Operating Modes
Sequence of Operation -
A heat pump equipped with
condenser water reheat can operate in three modes;
cooling, cooling with reheat (dehumidification), and
heating. The cooling/heating modes are like any other
Johnson Controls WSHPs. The reversing valve (“O”
signal) is energized in cooling, along with the compressor
contactor(s) and blower relay. In the heating mode the
reversing valve is de-energized. Almost any thermostat
will activate the heat pump in heating or cooling modes.
The DXM2 microprocessor board will accept either
heat pump (Y,O) thermostats or non-heat pump (Y,W)
thermostats. The reheat mode requires either a separate
humidistat/dehumidistat or a thermostat that has an
integrated dehumidification function for activation.
The DXM2 board is configured to work with either a
humidistat or dehumidistat input to terminal “H” (DIP
switch settings for the DXM2 board are shown below in
table 2). Upon receiving an “H” input, the DXM2 board
will activate the cooling mode and engage reheat. Tables
1 and 2 show the relationship between thermostat input
signals and unit operation. There are four operational
inputs for single stage units and six operational inputs for
dual stage units:
- Fan Only
- 1st Stage Cooling
- 2nd Stage Cooling
- 1st Stage Heating
- 2nd Stage Heating
- Reheat Mode
• Fan Only:
A (G) call from the thermostat to the (G)
terminal of the DXM2 control board will bring the unit
on in fan only mode.
• 1st Stage Cooling:
A simultaneous call from (G),
(Y1), and (O) to the (G), (Y1), (O/W2) terminals of the
DXM control board will bring the unit on in 1st Stage
Cooling.
• 2nd Stage Cooling:
A simultaneous call from (G),
(Y1), (Y2), and (O) to the (G), (Y1), (Y2), and (O/W2)
terminals of the DXM2 control board will bring the unit
on in 2nd Stage Cooling. When the call is satisfied at
the thermostat the unit will continue to run in 1st Stage
Cooling until the 1st Stage Cooling call is removed or
satisfied, shutting down the unit.
NOTE: Not all units
have two-stage cooling functionality.
(e.g. JRE036-072 units)
