How to Tell the Difference Between an AC Unit and a Heat Pump


Standard air conditioner and heat pumps can appear nearly identical from the outside, making it quite difficult to know which type of system you have at first glance. However, with just a tiny but of deeper inspection and understanding, you can quickly identify if you have an AC unit or a heat pump. We are going to share some super simple ways to determine which system you have on your property.

Find the Emergency Heat Setting on the Thermostat

If the thermostat in your home has a button or switch for an “emergency heat” setting, you have a heat pump, rather than a standard AC unit. The emergency heat setting is specifically unique to heat pumps and offers the capability to switch to your backup heating source, like a gas furnace, if the heat pump malfunctions for some reason. 

How to find the Emergency Heat Setting:

Go to the thermostat and look for a button, switch, or mode indicator, labeled “EM,” “EMER,” or “EMERGENCY” heat. If your thermostat has a digital display, it may appear directly on the screen. 

Turn on the Heat and Examine the Outside Unit

If you were unable to identify the emergency heat setting on your thermostat, let’s try a different method. Turn your thermostat to “heat” mode then go outside to your unit and see if it kicks on. If the outdoor unit is on, you have a heat pump, rather than a regular air conditioner. You see, heat pumps absorb heat from the outside air and blow it throughout your home. Essentially, if you have a heat pump, you will be able to hear the outdoor unit turn on whenever your thermostat is set to “heat” mode.

There are other types of heating systems, such as furnaces, that do not use the outdoor AC unit to heat up your home. If you have an alternative heating system, your outdoor air conditioning unit should not turn on at all while the thermostat is in heating mode. 

Analyze the Labels on the Outdoor Unit

Every outdoor unit, whether it be an AC or a heat pump, should have a label somewhere on the side that depicts either a Manufacturer Label or an Energy Guide Label. This is where you should be able to find information depicting whether you have a heat pump or a standard air conditioning unit.

The Manufacturer Label reveals all the specifications of the unit, which should hopefully give you a concise understanding of which type of unit you have. If the model number of the system begins with “HP,” this indicated that your unit is a heat pump. 

The Energy Guide Label is typically a bright yellow sticker on the outside of the outdoor unit. Look for a number labeled “SEER,” which stands for Seasonal Energy Efficiency Ratio and another one labled “HSPF,” which stands for Heating Seasonal Performance Factor. If you find these numbers on your Energy Guide Label, then you have a heat pump. Heat pumps provide both heating and cooling capabilities, therefore they use SEER ratings to determine how well they cool, and HSPF ratings to determine how well they heat. 

If you’re having trouble locating the information on the labels, try to at least find a model  number to write down and search it online. You should be able to find out more information as to whether your unit is a heat pump or a standard AC unit by looking directly at the manufacturer’s website. 

Find the Reversing Valve Inside the Outdoor Unit

If all else fails, this last method will definitely help you figure out the answer to that million dollar question. Take a peek inside the outdoor unit to see if you find a reversing valve, which is exclusive to heat pumps. The reversing valve reverses the flow of refrigerant, allowing the heat pump to switch from cooling mode to heating mode. If you see a reversing valve inside the unit, then you have a heat pump. 

What Does a Reversing Valve Look Like?

The first thing you need to do when looking for a reversing valve, is to make sure your system is completely turned off. This will ensure that the fan is not spinning. Then you will look directly inside the top of the outdoor unit and locate a brass-colored component with three fittings on one of the sides. This device is the reversing valve, meaning you have a heat pump. If you cannot find the reversing valve, then you most likely have an air conditioning unit. 

Call FiveStar Plumbing & HVAC for More Information

If you are still having trouble determining which type of heating or cooling system you have, please give us a call at (615) 382-8131. Our certified HVAC technicians can help you quickly determine the type of unit you have, as well as answer any questions you may have. FiveStar is Nashville’s most trusted team of HVAC professionals for more than 40 years! Make an appointment online or give us a call today!