Quick Start Manual
26
Installation, Operation & Maintenance  HEV/H SERIES  Heat Controller, LLC.
ELECTRICAL - THERMOSTAT WIRING
Figure 24: Typical Thermostat 2 Heat/1 Cool
Thermostat Installation
The thermostat should be located on an interior wall in a 
larger room, away from supply duct drafts. DO NOT locate 
the thermostat in areas subject to sunlight, drafts or on 
external walls. The wire access hole behind the thermostat 
may in certain cases need to be sealed to prevent erroneous 
temperature measurement. Position the thermostat back 
plate against the wall so that it appears level and so the 
thermostat wires protrude through the middle of the back 
plate. Mark the position of the back plate mounting holes 
and drill holes with a 3/16” (5mm) bit. Install supplied 
anchors and secure plate to the wall. Thermostat wire must 
be 18 AWG wire. Wire the appropriate thermostat as shown 
in Figures 24a and 24b to the low voltage terminal strip 
on the DXM2 control board. Practically any heat pump 
thermostat will work with these units, provided it has the 
correct number of heating and cooling stages. However, 
using the communicating thermostat (ATC32) is highly 
recommended for on-site, easier confi guration, monitoring 
and diagnosis.
ATM21U01 Thermostat
Connection to DXM2 Control
Compressor
Heating Stage 2
Reversing Valve
Fan
24Vac Hot
24Vac Common
Fault LED
Y
Y2/W
O
G
R
C
L
Y1
W
O
G
R
C
AL1
DXM2
(Using 2 Heat / 1 Cool thermostat is not 
recommended if maximum efficiency is desired)
iGate™ Thermostat
ATC32U** 
24Vac Hot
DXM2
24V
Comm +
A+
A+
Comm -
B-
B-
OD
ID
GND
Outdoor
Sensor
(Optiona)
Remote Indoor
Sensor
(Optiona)
24Vac Common
Gnd
R
C
Figure 23a: Communicating Thermostat Connection to 
 DXM2 Control
Figure 23b: Conventional 3 Heat / 2 Cool Thermostat 
  Connection to DXM2 Control
 CAUTION! 
CAUTION! Refrigerant pressure activated water regulating 
valves should never be used with manufacturer’s 
equipment.
Thermostat
Compressor
Compressor Stage 2
Reversing Valve
Fan
24Vac Hot
24Vac Common
Fault LED
DXM2
Board
Y1
Y2
W
H
O
G
R
C
AL1
Y1
Y2
W
DH
O
G
R
C
L
Dehumidification
Notes:
Auxiliary Heat
1) ECM automatic dehumidification mode operates with dehumidification airflows 
  in the cooling mode when the dehumidification output from thermostat is active. 
  Normal heating and cooling airflows are not affected.
2) DXM2 board DIP switch S2-7 must be in the auto dehumidification mode for 
 automatic dehumidification
3)  DH connection not possible with units with internal pump. Use ATC32U**.
4) Only use ATC Communicating Thermostat when using Humidifier (H Input) with 
  units with internal flow controller.
Communicating Thermostat.
Only use Communicating Thermostat when using Humidifi er (H Input) with 
units with internal fl ow controller.










