The following is a list of abbreviations you will see throughout the installation guide and support articles related to the iDevices Thermostat.
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.