Why Does My Heat Pump Run All Night?

November 07, 2017

heat pump troubleshooting

If you noticed that your heat pump is running constantly during cold winter nights, you’re probably wondering if it’s normal or if there’s something wrong with your unit.

Well, first, answer these 2 questions:

  • Is your heat pump meeting your set temperature?
  • Is the temperature outside under 20–30 degrees?

If you answered yes to both of these questions, it’s normal (more on that later).

But if the temperature outside is over 30 degrees and the heat pump, despite running constantly, isn’t able to meet your set temperature, you likely have one of these problems:

  • A refrigerant leak
  • The outdoor unit isn’t running
  • You have an undersized system
  • The heat pump is running in AC mode

Don’t worry, we’ll explain how you’ll know whether there’s a problem with your heat pump or not—and possibly save you from making an unnecessary service call.

Need professional heat pump help right away? Just contact us and we’ll send out a tech to inspect your heat pump.

It’s probably normal if it’s under 30 degrees outside

Unlike a furnace, your heat pump doesn’t create heat; it simply moves heat from one place to another (from outside to inside or vice versa in the summer).

So on particularly cold days, when there’s very little heat in the outside air, your heat pump can only move a little bit of heat indoors, meaning it will have to run constantly just to keep your home at a constant, comfortable temperature.

So does that mean a heat pump won’t keep you warm in very cold temperatures? Not at all. 

In fact, when temperatures outside are too low for a heat pump to pull heat from the outdoor air, a temperature sensor in the outdoor unit turns on a “backup” heating system. Depending on what area of the country you live in, the backup heat will kick on when outdoor temperatures fall below 20–40 degrees Fahrenheit. And depending on the kind of heat pump system you have, your backup heating source is either electric resistance coils (think giant toasters) or a furnace. 

Related reading: 

Bottom line: It’s normal for your heat pump to run constantly in colder temperatures.

But what if your heat pump is running constantly and outdoor temperatures are OVER 30 degrees? Well, then you likely have a problem. Let’s take a look at some of the problems you may have...

It’s not normal if the temperature outside is over 30 degrees...

If your heat pump is running non-stop but there’s plenty of heat available in the outdoor air to warm your home, you likely have one of these 4 problems and will need professional heat pump repair.

A refrigerant leak

Your heat pump uses refrigerant to absorb and transfer heat from the outside air into your home. So, if there’s a leak and refrigerant levels are lower than normal, the heat pump will struggle to cool your home—even when there’s plenty of heat in the outdoor air to warm your home.

Signs of a refrigerant leak:

  • Higher than normal energy bills
  • Heat pump is blowing cold air
  • Hissing or bubbling noise along the refrigerant lines
  • Iced over refrigerant lines/outdoor unit

Want to learn more about refrigerant leaks? Check out our blog, “How Often Do Air Conditioners Need Refrigerant?

The outdoor unit isn’t running

In heating mode, the heat pump’s outdoor unit is responsible for absorbing heat and pushing it indoors. So if something happened to the outdoor unit to prevent it from running (such as a tripped circuit breaker, faulty thermostat or even burnt wires), you’ll likely have an indoor system that runs constantly without any heating results.

If your outdoor unit isn’t running, first check:

  1. Your thermostat settings. Make sure the thermostat is set to HEAT and the fan setting is set to AUTO.
  2. Your heat pump’s circuit breaker. If the circuit breaker is tripped, try flipping it back to the ON position. If the circuit breaker immediately trips again once the heat pump starts, DON’T attempt to flip the breaker again (this is a sign of a larger electrical problem that needs to be handled by a professional).

If your outdoor unit still isn’t running, have a professional troubleshoot and repair the unit.

You have an undersized system

A heat pump should be specifically sized for your home. You see, heat pumps (and air conditioners for that matter) are sized according to how much heat it can add to or remove from your home. So, if the unit is actually too small, it will never fully heat your home and will run constantly trying to deliver your desired temperature.

The heat pump is running in AC mode

A heat pump can provide heating and cooling. By reversing the direction of the refrigerant, your heat pump can switch from AC to heating. However, if something is wrong with the solenoid valve (the valve that switches the direction of the refrigerant), your heat pump could get stuck in AC mode. And if it’s stuck in cooling mode, it will run all night (and day) without ever hitting your desired temperature.

Need heat pump repair in the Kansas City Metro area?

If you think your heat pump has a problem and needs professional repair, we can help.

Just contact us. We’ll send over a tech who can inspect and repair your heat pump quickly.

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