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Installation, Operation & Maintenance WDG AIR HANDLER SERIES Heat Controller, LLC

Electrical - Thermostat Wiring

 CAUTION! 

CAUTION! Many units are installed with a factory or ﬁ eld

supplied manual or electric shut-off valve. DAMAGE WILL

OCCUR if shut-off valve is closed during unit operation. A

high pressure switch must be installed on the heat pump side

of any ﬁ eld provided shut-off valves and connected to the

heat pump controls in series with the built-in refrigerant circuit

high pressure switch to disable compressor operation if water

pressure exceeds pressure switch setting. The ﬁ eld installed

high pressure switch shall have a cut-out pressure of 300 psig

and a cut-in pressure of 250 psig. This pressure switch can

be ordered from the manufacturer with a 1/4” internal ﬂ are

connection as part number 39B0005N02.

CAUTION! Refrigerant pressure activated water regulating

valves should never be used with the manufacturer’s equipment.

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 6 and 7 to the low voltage terminal strip on

the ECM control board. Practically any heat pump thermostat

will work with these units, provided it has the correct number of

heating and cooling stages.

Figure 7: Three Heat / Two Cool, Auto / Manual

Changeover Programmable (7 Day) - Non-

Programmable, With Humidity Control

Units with ECM Fan

Figure 6: Three Heat / Two Cool, Manual / Auto

Changeover Programmable

Units with ECM Fan

Field Wiring

Factory Wiring

Field Wiring

Factory Wiring

See equipment wiring diagram for more details.

Notes:

1) ECM dehumidification mode slows down fan speed in the

cooling mode when dehumidification output from thermostat is

active. Normal heating and cooling fan speeds are not

affected.

2) ECM board DIP switch SW9 must be in dehumid. mode.

ATP32U03 Thermostat

Connection to ECM Control

Compressor

Compressor Stage 2

Reversing Valve

Fan

24Vac Hot

24Vac Common

Fault LED

AL1

ECM

Electric Heat

ATP32U04 Thermostat