Heat Controller HEV/H manual Electrical - Low Voltage Wiring, DXM2 PCB, Hev/H Series

Installation, Operation & Maintenance HEV/H SERIES Heat Controller, Inc.

ELECTRICAL - LOW VOLTAGE WIRING

Thermostat Connections

The thermostat should be wired directly to the DXM2 board. See “Electrical – Thermostat” for specific terminal connections.

Figure 21: Low Voltage Field Wiring

		Capacitator
		Circ Brkr
Grnd	Loop PB1	HWG PB2
Contactor - CC

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 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 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 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].

BR

Transformer

DXM 2

Figure 22: LT1 Limit Setting

Fault Status

HP

LP

LP

LT1

LT1

CB

Low Voltage

Connector

Rev.: 3/24/00

c1 ay

c2 ay

Off On

1 2 3 4

S3 Off On

1 2 3 4 5 6 7 8

S1

Off On

1 2 3 4 5 6 7 8

S2

A0-1 A0-2

JW3

CCH

Relay

LT2

LT2

RV

RV

CO

12 CO

RV P7 Relay

1 24Vdc

EH1

4 EH2

Comp P6

Relay

CCG

P11P10

AO2 Gnd T1 T2 T2 T3 T3 T4 T4

P9 CC

T5 T5 T6 T6

DXM2 PCB

JW3-LT1 jumper should be clipped

for low temperature operation

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