Abbreviations - iDevices HVAC Installation Manual

Abbreviations

HVAC: Heating, Ventilation and Air
Conditioning system
HP: Heat Pump System. This type of HVAC
system uses a compressor with a reversing valve
to provide both heating and cooling capability.
HE: Electrically heated central heating system.
This system uses an electric heating element
along with a fan and ducting. Sometimes used as
AUX/Emergency heat with a heat pump system.
Electric baseboard heaters are not included in this
system type.
HG: Fuel-fired central heating system. This system
uses a gas or oil burner along with a fan and
ducting or a hot water baseboard system. Can be
used as a standalone heating system or as AUX/
Emergency heat with a heat pump system.
O/B: This option selects the type of reversing
valve for heat pump systems. An "O" reversing
valve is energized when cooling and a "B"
reversing valve is energized when heating. Most
systems use an O type reversing valve. Rheem
and Ruud typically use a B type reversing valve.
If you are unsure, contact your Heat Pump
manufacturer.
Terminal Assignments
For reference, standard wiring assignments for
typical HVAC systems are provided below.
Terminal
(HP)
C
L
G
Y1
Y2
RC
RH
O/B
E
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Heat Pump
Terminal
System
(Non-HP)
(HP)
C 24VAC common for control
circuit and thermostat power
input
L System
monitor
G Fan
Y1 1st stage
compressor
Y2 2nd stage
compressor
RC 24VAC power supply for cooling
side
RH 24VAC power supply for heating
side
W1 Changeover
valve
W2 AUX/
Emergency
heat
Conventional
System
(Non-HP)
Not used
1st stage
cooling
2nd stage
cooling
1st stage
heating
2nd stage
heating
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