Electrical Wiring

Heat Pump Wiring

Summary: Heat pumps are used for heating and cooling. Wall mounted units are great for offices, sunrooms, room additions, garages and are used in hotel and motel rooms.

The Basics about Heat Pumps and the Electrical Requirements

What is a Heat Pump that is Wall Mounted?
Heat pumps are very similar to cooling-only systems, with one exception. A special valve in the refrigeration system allows the refrigeration cycle to be operated in reverse.

A cooling only system cools the indoor air and discharges heat to the outdoors. A heat pump that is wall mounted can also cool the indoor air, but when the valve is reversed, the indoor air is heated.

A supplementary electric heater may also be used to assist the heat pump at lower outdoor temperatures. In colder climates, heat pumps do require a defrost period, during which the electric heater is the primary source of heating the interior of the building.

Heat Pump Wall Mounted Unit
Control Panel
Heat Pump Control Panel

What is a PTAC / PTHP Heat Pump?
A PTAC ( packaged terminal air conditioner) is a unit that cools and heats. These are heat pumps wall mounted for space saving and convenience.

A PTAC provides warm air using an electric heater (heat strip). A PTHP ( packaged terminal heat pump) uses its compressor all year round to either heat or cool. In warm weather, they efficiently capture heat from inside the building and pump it outside for cooling.
How a Heat Pump Wall Mounted Works
In cool weather, they capture heat from outdoor air and pump it into the building, adding heat from electric heat strips as necessary, in order to efficiently provide heat.

When the external temperature is 38 degrees Fahrenheit or lower, a PTHP unit switches to heat strip operation in order to provide heat. PTHP units are similar to a high quality version of the window-mounted air conditioner with the heat pump accessories added.
Heat pumps wall mounted models are often called "through-the-wall" units since they are usually installed in a sleeve passing through the outdoor building wall. PTHP's are completely self contained, requiring only a permanent electrical connection. They use the outdoor air as the heat source in winter and as a heat sink in summer. They can also provide air assisted ventilation. These heat pumps wall mounted units are typically used in hotel and motel rooms and are also great for offices, sunrooms, room additions, and garages.

Electric Circuit Requirements
The heat pumps wall mounted will require their own dedicated power electric circuit. The size of the electric circuit will depend on the size of the heat pump unit. These heat pumps wall mounted are sized to the space required to be conditioned.