Electrical - thermostat wiring, Caution – Comfort-Aire WDG Air Handler Series User Manual

Page 13

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

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