Heat Controller HTV, HTH, HTD manual Electrical Low Voltage Wiring, Thermostat Connections

Installation, Operation & Maintenance HTV/HTD/HTH SERIES Heat Controller, Inc.

Electrical - Low Voltage Wiring

Thermostat Connections

The thermostat should be wired directly to the CXM board (units with PSC fan). Units with optional ECM motor include factory wiring from the CXM board to the ECM interface board. Thermostat wiring for these units should be connected to the ECM interface board. Figure 18 shows wiring for TT/ HTTS units with PSC or optional ECM motor. See “Electrical – Thermostat” for speciÄc terminal connections.

Figure 18: HTT/TSLowLowVoltageVoltageFieldFieldWiringWiring

Low voltage Äeld wiring for units with

PSC FAN (ECM board will not be present)

Low voltage Äeld wiring for units with ECM fan

Low Water Temperature Cutout Selection

The CXM control allows the Äeld 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 Åow 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 (extended range) applications with antifreeze (most ground loops), jumper JW3 should be clipped as shown in Figure 19 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].

Figure 19: FP1 Limit Setting

	JW3-FP1
	jumper should
	be clipped for
CXM PCB	low temperature
	operation

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