Quick Start Manual

20
Heat Controller, Inc. HP SerieS Installation, Operation & Maintenance
24
ELECTRICAL - LOW VOLTAGE WIRING
Figure 21: Low Voltage Field Wiring
Figure 22: FP1 Limit Setting
CXM PCB
JW3-FP1
jumper should
be clipped for
low temperature
operation
Thermostat Connections
The thermostat should be wired directly to the CXM
board. See “Electrical – Thermostat” for specific terminal
connections.
Rev.: 3/24/00
BR
Contactor - CC
Capacitator
Loop PB1 HWG PB2
CXM Control
Low Voltage
Connector
Transformer
CB
Circ Brkr
Grnd
Low Water Temperature Cutout Selection
The CXM 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 FP1. Note that the FP1
thermistor is located on the refrigerant line between the
coaxial heat exchanger and expansion device (TXV).
Therefore, FP1 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 FP1 is for systems using water
(30°F [-1.1°C] refrigerant temperature). In low water
temperature applications with antifreeze (most ground
loops), jumper JW3 should be clipped as shown in Figure
22 to change the setting to 10°F [-12.2°C] refrigerant
temperature, a more suitable temperature when using
an antifreeze solution. All residential units include
water/refrigerant circuit insulation to prevent internal
condensation, which is required when operating with
entering water temperatures below 59°F [15°C].