Trane PTHC-090 - HEAT;OFF; COOL Switch; Fan Switch

PTEC-M-1A
18
Chassis
Information
WARNING!
Hazardous Voltage!
Disconnect all electric power,
including remote disconnects before
servicing. Follow proper lockout/
tagout procedures to ensure the
power can not be inadvertently
energized. Failure to disconnect
power before servicing could result
in death or serious injury.
Wiring Schematic for
Remote Heat Pump
Wiring Schematic for
Straight Cool Unit
HEAT/ OFF/ COOL Switch
• OFF - cooling and heating functions
are defeated.
• HEAT - the selected room
temperature is maintained by
cycling either in the heat pump
mode or electric strip heat. A PTHC
unit is switched from the heat
pump mode to electric heat when
the outdoor coil temperature is
below 25°F (approximately), or
when the heat pump cannot keep
up with the heating load and a two
stage thermostat is used.
• COOL - the selected room
temperature is maintained by
cycling the air conditioner.
Fan Switch
• AUTO - the fan cycles with the
compressor or electric strip heat.
• ON - the fan runs continuously
regardless of any other settings.
The table below summarizes the
thermostat input combinations and
the respective unit functions.
The following figures show wiring
schematics for heat pump and
straight cool units with electric
resistance heat, respectively. Remote
hydronic heat installations should be
wired similar as for a straight cooling
unit.
Note: A heat pump thermostat (no
W1 terminal) can be used for a
straight cooling units. Connect
thermostat to unit according to the
schematic for remote heat pumps.
1. For heat pump operation, a room
thermostat with a “B” (heating
changeover) terminal is required.
This will mean that some “auto
changeover” thermostats cannot
be used, as many of them either
do not have a “B” terminal, or
else energize the “B” terminal
continuously when in the “ auto”
position.
2. The maximum power
consumption of any thermostat is
1.2 watts.
Unit Pump Electric Heat
Unit Thermostat Thermostat
Function Input Input
R Terminal to: R Terminal to:
OFF NONE NONE
Heat Stage 1 GL*, Y/W1, B
Gl*, Y/W1, B or
GL*, W2
Stage 2 GL*, W2 n/a
Cool GL*, Y/W GL*, Y/W1
*or GH depending on speed required.