As a realtor you usually need to say on the MLS if a home has an A/C unit or a heat pump. The following is some information I hope you find useful to correctly identify the unit.

A heat pump is a single unit that works as an air conditioner in the summer and a heater in winter. In hot weather, a heat pump extracts heat energy out of the cold air inside the home and pumps it outside. In cold weather, it acts as an A/C in reverse — it extracts heat energy from the cold air outside and pumps it inside. When it is very cold outside, a heat pump needs help from a backup furnace. Nevertheless, homes with heat pumps generally have lower power bills.

The main part of a heat pump, the compressor, sits outside the house, and looks very similar to a typical A/C unit. Here are some ways to tell them apart. None of them are foolproof, so you may want to use more than one.

Set the thermostat for just a few degrees above the current temperature (in heating mode) and go outside to see if the compressor is running. If you go too many degrees up, the backup furnace will come on, so make just a small adjustment in temperature. The only time this would not work is if it was very cold outside and the heat pump is in a defrost cycle.
Look at the manufacturer plates on the outside compressor unit, or the air handler/furnace unit inside. It may say if it is a heat pump. It’s also a good idea to Google the serial number because sometimes the manufacturer plate says it is an air conditioning unit, but it can still be a heat pump.
On a thermostat for a heat pump you should see a setting called “emergency heat”. This is not foolproof because I have found A/C thermostats used for heat pumps. The emergency, or auxiliary, heat turns on when the heat pump alone cannot warm the house to the desired temperature and a backup furnace will come on to boost the temperature.
Heat pumps will be up on 4 inch plastic legs that allow for water to drain when it is in defrost cycle. A/C units will usually sit directly on a cement or brick pad.

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