C L I M A T E M A S T E R W A T E R - S O U R C E H E A T P U M P S
TSL Vertical Stack
R e v. : 0 4 / 2 4 / 2 0 1 9
28
C l i m a t e M a s t e r Wa t e r - S o u rc e H e a t P u m p s
JW3 should never be clipped for equipment or
systems without correct antifreeze mixture.
NOTICE!
Electrical Wiring - Low Voltage
Thermostat Connections -
The thermostat can be
spliced or wired directly to the CXM or DXM2 board. See
Unit Wire Diagram. Review the appropriate thermostat
AOM (Application, Operation and Maintenance) manual.
Wall Sensors (ASW) for MPC or LON -
Connections are
made to DDC controller, see Unit Wire Diagram.
Cabinets with MPC or LON (model digit 5 is C,D,L,M
or U) requires fi eld to clip JW1 jumper on CXM or
DXM2 board in chassis.
Low Water Temperature Cutout Selection -
The CXM/
DXM2 control allows the fi eld selection of low water (or
water-antifreeze solution) temperature limit by clipping
jumper JW3, which changes the sensing temperature as-
sociated with thermistor LT1. Note that the LT1 thermistor
is located on the refrigerant 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 fl ow rate and
temperature is affecting the refrigeration circuit.
The factory setting for LT1 is for systems using water
no lower than 50ºF (10ºC), boiler tower or open loop.
Water temperature below 50ºF (10ºC) (extended range)
applications must use antifreeze (most ground loops),
jumper JW3 must be clipped as shown in Figure 8.
Lowest refrigerant temperature, LT1 can sense without
faulting off is, with LT1 unclipped - 30ºF (-1ºC) and
clipped - 10ºF (-12ºC). All ClimateMaster units operating
with entering water temperatures below 59°F [15°C] must
include the optional water/refrigerant circuit insulation
package to prevent internal condensation.
Figure 13: LT1 Limit Setting
CXM PCB
LT1
LT2
JW3-LT1 jumper
should be
clipped for low
temperature
operation