How Hot Should the Air Be From a Heat Pump


Heat pumps transfer heat from the outside air into your home, making them an efficient and cost-effective method of heating and cooling. However, heat pump output will vary depending on the outside temperature and your thermostat’s settings.

So, how hot should the air be from a heat pump? The average temperature output of a heat pump is 85°F to 92°F in heat mode without auxiliary heat. Typically, a heat pump will produce a temperature differential of 15-20°F warmer than the current air temperature in heat mode. The air temperature from a heat pump can vary based on the age and condition of your heat pump.

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This article will further explore some questions you may have about your heat pump and its use. Keep reading to learn more about how you should work your heat pump and save money on your energy bill!

The average heat output can be 85-92°F; however, how warm the output from your heat pump will be is determined by several factors, including age and condition of the heat pump. Newer heat pumps with R410a refrigerants can extract more heat from the outside air, which improves output.

The table below shows a comparison of the output from a heat pump compared to electric and gas furnaces.

Heat Source Output Ranges Output Temperature
Heat Pump without Aux Heat: 85-92°F
Heat Pump with Aux Heat: 105-125°F
Gas Furnace: 130-140°F
Electric Furnace: 105-125°F

If your heat pump is not producing hot air, see our article 16 Reasons Your Heat Pump Doesn’t Blow Hot Air.

At What Temperature Should AUX Heat Come On?

Heat pumps use refrigerant and heat exchangers to extract heat from the outside air, even in cold weather. However, below 30 degrees, they lose a lot of their efficiency and need assistance to keep up with demand from the thermostat.

So, what temperature will Aux heat turn on? The heat pump will engage the aux heat automatically when the outside air temperature is below 30°F. The heat pump will also use emergency aux heat in heat mode if the thermostat is raised more the 2°F.

For example, if the outside temperature is 40°F, and the indoor thermostat reads 67°F, setting the thermostat is 74°F would engage the aux heat to assist in meeting the desired temperature of 74°F as quickly as possible.

Because heat pumps use the air from outside, they often require help heating your house when the weather is very cold. As a result of this trait, AUX heat kicks on in low temperatures. To understand the best temperature for AUX heat, you must first understand what it is and how it works.

What Is AUX Heat?

Heat pumps extract heat from the outside air to heat your house. This can be hard to do in very cold weather. Unfortunately, this means when the air is very cold, the heat brought in by the heat pump is less than the heat loss from the building. In this case, Aux heat is needed to meet demand for the house.

Aux heat (also known as an auxiliary, supplemental, or emergency heat source) can be a gas furnace or electric heat strip backup that turns on to assist the heat pump in heating the house when the temperature drops below 30°F.

Aux heat assists the compression heat from the heat pump to keep you warm in cold weather.

It is important to understand that auxiliary heat is not used all the time. In fact, you can go months in the summer without using your AUX heat and relying on your heat pump.

Depending on where you live, Auxiliary heat is generally used in the winter and late fall when it is cold. People in the North will use their AUX heat more often, but if you live in the South where the climate is warmer, you can often avoid it.

Finally, Auxiliary heat is used with your heat pump, distinguishing it from emergency heat.

AUX Heat vs. Emergency Heat

Many people confuse auxiliary heat and emergency heat. There is no real difference in the two and it references the same components inside your heat pump. Auxiliary heat and emergency heat use the same heat strips or gas backup furnace.

The difference between Aux heat and Emergency Heat is simple: Emergency heat is a setting on the thermostat that allows you to bypass the heat pump and run off the electric heat strips only. Aux heat is the combination of heat strips and the heat pump to heat the house that occurs automatically without you doing anything.

Furthermore, Auxiliary heat will automatically turn on at a certain temperature. Emergency heat should be manually turned on by the homeowner if there is a problem with the heat pump. If emergency heat turns on automatically, your heat pump may be damaged or broken.

Emergency Heat

Emergency heat can be turned on when your heat pump is not working or is damaged. This setting causes your thermostat and heat system to automatically get heat from your second stage heat source, which may be a furnace or electric heat strip.

When emergency heat is used, your heat pump is not. Overall, emergency heat is made to warm your house if there is a problem with your heat pump or if it cannot properly heat your house.

What Temperature should AUX Heat Come On?

Your auxiliary heat should turn on when the outside temperature is 30° Fahrenheit and below. This temperature is when your heat pump struggles to obtain enough heat from the outside air to warm your house. Therefore, when the temperature is below 30 degrees, AUX heat is needed to supplement your heat pump.

When this 30-degree temperature is reached, your AUX heat should turn on automatically- you do not need to manually operate it. If your auxiliary heat is on when the weather is warm, you should contact a professional to help you find the problem.

What Temperature Should I Set My Heat Pump in the Winter?

When it comes to operating your thermostat settings during the winter, we encourage homeowners to set the heat as low as you can stand it. This will be different for everyone.

Ideally, the most efficient setting during the winter is to set the temperature to 68°F and leave the thermostat alone. If you need it warmer, raise the temperature by 1° until you find your ideal comfort setting.

Considering a dual fuel heat pump? See our article Are Dual Fuel Heat Pumps Worth It? What You Need to Know.

As I have discussed, heat pumps operate by drawing energy from their surroundings and using it to raise the temperature for heating or lower it for cooling. Moreover, the larger the difference in temperature between the outside air and the temperature you want inside, the lower the efficiency of the heat pump system.

This inefficiency can make your heating system burn more energy and drive up your energy bills. Fundamentally, the best way to reduce the inefficiency and avoid high energy bills is reducing the gap between the outside temperature and your thermostat.

Frequently setting your thermostat at a high temperature, especially in the winter, escalates your house’s energy loss and increases your energy bill.

However, setting your thermostat at a low temperature is not feasible for chilly winter days when you want to keep warm. Luckily, setting your heat pump at the right temperature can help reduce your energy bill and maximize your heat pump’s effectiveness.

To maximize comfort and efficiency, you should set your thermostat to between 68 and 72° Fahrenheit. This temperature is comfortable for most people and will keep everyone warm in typical clothing while minimizing heat loss.

When no one is in your house, setting your heat pump to between 58 and 62 degrees Fahrenheit will enable you to save money on heating without worrying about making a family member cold or uncomfortable.

Should Heat Pumps Run Continuously in the Winter?

Although heat pumps are less effective in very cold and below-freezing temperatures. Without the assistance of aux heat, a heat pump can technically run continuously in the winter. However, to save money and energy, you should not run your heat pump continuously in the winter- always turn it off when it is not in use.

For example, if you will be gone overnight or all day, you can turn your heat pump off and set a timer, so it turns back on before you return. If you set your timer to turn about a half an hour before you get home, it should be warm upon arrival.

Ultimately, turning your heat pump off whenever possible will maximize savings. If you are especially concerned with saving money during wintertime, you can even set your timer, so your heat pump turns off for a few hours at night while you sleep, then kicks back on before you wake up! 

Conclusion 

Overall, the heat pump should be about twenty degrees hotter than the outside temperature when it is in heat mode. When it is too cold outside for your heat pump to keep up with your heating needs, the Auxiliary heat will supplement it to keep your house warm. 

This is often necessary for the winter when heat pumps are less effective, and you should set your heat pump between 68 and 72° Fahrenheit (20 to 22° Celsius) to maximize efficiency. 

Finally, do not keep your heat pump running continuously in the winter, or your energy bills will be higher- try to turn off your heat pump whenever it is not in use.

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.

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