Heat Pump HVAC System Setup
Heat Pump Type Selection.
For Heat Pump systems, set the HVAC system type, SW1 position 1 to the
ON position (SW1-1 = ON).
Change Over Selection.
Heat Pump systems change from heating to cooling by reversing the direction
of refrigerant flow in the system. The change from Heating to Cooling is controlled by the CHANGEOVER
(CO) output from the Control Unit (also referred to as the “reversing valve” output). These are the O
and/or B terminals on Heat Pump thermostat connections. Always use the O terminal input on the Heat
Pump system and select the CO type on the controller as required.
Changeover with Cooling.
This is typical of most heat pump systems, which are designed to work
normally in the heating mode and require a changeover output for cooling. To select this CO type, set
dipswitch SW1 position 3 to the OFF position (SW1-3 = OFF). This is the default setting.
Changeover with Heating.
If your system requires changeover with heating, set SW1 position 3 to ON
position (SW1-3 = ON).
Changeover Relay Operation:
The changeover relay output stays ON after a heating/cooling call for the
duration of the MOT minimum off delay period. If another call occurs before the delay period expires, the
CO relay will already be on and this avoids continuous on/off cycling the CO valve for each call. After the
MOT period expires and another call is not active, the CO output will go OFF.
TR16 Control Unit HVAC System Outputs for Heat Pump Systems
Operating Mode
Changeover with Cool
Changeover with Heat
Manual Fan
G
G
Cooling Stage 1
G, O, Y1
G, Y1,
Cooling Stage 2
G, O, Y1, Y2
G, Y1, Y2,
Heating Stage 1
G, Y1
G, O, Y1,
Heating Stage 2
G, Y1, Y2
G, O, Y1, Y2
Heating Stage 3
G, Y1, Y2, W1
G, O, Y1, Y2, W1
Emergency Heat
G, W1
G, W1
Status LEDs
The Control Unit has a Status LED on the circuit board that will normally blink on and off slowly as a
system heartbeat. During short cycle protection delay periods, the LED will blink twice for each heartbeat.
This indicates that the compressor is locked out during this time. The other LEDs indicate the operation of
the control unit output relays. When the LED’s are on, the output relay is on.
LED
Function
Control Unit Output
H1
Heat stage 1 output (Heat stage 3 for HP systems)
W1
Fan
Fan output
G
C1
Compressor stage 1 output
Y1
C2
Compressor stage 2 output
Y2
H2/CO
H2 =
Heat stage 2 output for
Standard HVAC systems
CO
= Changeover valve output for
Heat Pump HVAC systems
.
O (W2)
O
Heat Pump changeover (reversing valve) output is dependent on the control unit Dipswitch SW1-3 setting.
Change over is either with cool (normal) or with heat.
DCN: 141-00930-09 7/13/06
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