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Do Heat Pumps Work Below Freezing?

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Heat pumps really are a lifesaver for any home. They’re responsible for keeping you toasty warm in the bitterly cold weather and keeping you cool and sweat-free in the blistering heat.

There’s not much worse than that sticky claustrophobic feeling when you’re overheating with no way to cool down.

There’s really only one thing that’s worse in my opinion and that’s being bitterly cold with no possible way of warming up. 

So when the temperature drops below freezing, it can be a real challenge.

But before you go grabbing the bundles of blankets and sit shivering in your home know this; you can still use your heat pumps even when the temperature has dropped below freezing.

So, relax and let yourself warm up while I explain everything you’ll need to know

Heat pumps are good to go until you hit about 25 degrees Fahrenheit. Modern designs are built to cope with the cold a lot better than the older ones, but whichever you own old or new, you should be fine.

However, once you’ve exceeded this temperature you’re going to start to have performance issues. So in this case, you’re going to need another heat source. 

So how do you use your pump during these colder months to keep it running as optimally as possible? Carry on reading to find out. 

How To Keep Your Heat Pump From Freezing During Winter

So to keep your pump working properly during these colder months when the temperature tends to drop, you need to try and prevent the heat pump itself from freezing (see also ‘Will Heat Pumps Work In Subzero Temperatures?‘) .

Now a heat pump, even just its exterior, freezing isn’t massively common so if this happens to you, you might want to check there isn’t a fault with your unit.

You’ll want to do this sooner than later, as it can cause severe and significant damage to the pump. 

For the pump to work, air needs to be able to pass through the unit’s fins.

If the motor can’t make air pass through these fins then there’s something broken within your heat pump and you need to make sure you fix it quick, or your pump will certainly freeze once the colder weather hits.

So it’s important to keep up a little maintenance during these months, below are all my top tips to help keep your pump from freezing during the cold. 

Air Filter Maintenance 

Keep an eye on your air filter once the transition from fall to winter begins. If the filter is broken or damaged it can cause your pump to freeze because of the blocked airflow.

If you inspect your filter and believe it to be the cause of the fault, give it a good clean, and if this doesn’t work replace it completely.

I would always advise checking the manufacturer instructions before you begin. 

Water Hose

Now, this isn’t by any means a permanent fix, but if you are stuck for a small amount of time, you can always grab your garden hose to fix a freezing heat pump.

You can use this to melt the build-up of ice on the unit. This is really the only method I’d recommend for trying to melt the ice as you’ll probably end up causing more damage to the pump if you try and heat the ice any other way. 

This is also, as aforementioned only a quick and temporary fix. You should not try this multiple times.

Once you’ve gotten rid of the ice build-up you should get your pump checked out by a professional, especially if it is freezing this badly, this often.  

Defrost Mode

What is ‘defrost mode’ I hear you ask, well it is when you turn your heat pump onto its air conditioning mode until it unfreezes the pump.

Once you’ve defrosted the pump you can then switch it back to heat mode and wait until the room is once again, nice and toasty.

You only need to leave your pump in air conditioning mode for about 10 to 15 minutes. 

Your pump should only ever need to be in defrost mode every 35-40 minutes or so, but this can depend on just how cold it is.

If it’s going into defrost mode any more frequently than this, that’s a pretty good indicator that there’s a problem with your pump because it’s freezing too easily. 

How do you know if your pump went into defrost mode? Well, the fans will stop while this happens, and on most models, there will be a light indicator to let you know. 

What Temperature Should Your Pump Be Set To During Winter

It’s best to keep your pump at about 68 degrees Fahrenheit as this is the optimal temperature for the best energy efficiency and not only this but it is best for your comfort too.

The Department of Energy also states that turning the temperature down just 7-10 degrees overnight while you sleep, or during the day for at least nine hours (perhaps while you’re at work) will save you up to at least 10% in your energy costs.

Do Heat Pumps Work Below Freezing

If you go over the recommended temperature adjustments it’s going to cause price rises in your energy consumption because your pump activates the backup electric heat strips and these use a lot of extra power.

And as the temperature drops, usually the power usage on these heat pumps (see also ‘Solved: Heat Pump Constantly Running‘) increases, and this can cause high jumps in your bills during the winter.

And let’s face it around Christmas is the last time period that you want to be hit with an expensive bill when there’s already so much else to pay for.  

Those 7-10 degrees will also significantly prolong the life of your pump and not listening to these recommendations just adds more pressure to your pump.

This pressure means the pump has to work twice as hard to get the temperature to what you’ve set it to.

If the gap between the temperatures is just too far apart, the motor will have to kick into overdrive and this can cause some proportionate damage. 

Are You Alright To Run A Heat Pump On Emergency Heat

Heat pumps have supplemental heating which you’ll usually find in the indoor unit.

If you use your emergency heat, it is the supplemental heating that you’re using, not the heat produced by the actual pump itself. 

So yes, you can run a heat pump on emergency heat. 

However, you should really only ever be using the emergency heat if your actual heat pump is broken or damaged.

This is because once again the power consumption from doing this can be extortionate and you do not want to be left with a hefty bill. 

The longer that you’re using emergency heat, the bigger the bill you’re going to end up being stuck with. They’re also not really designed to be used for long periods of time so your heat pump will be more efficient if it is running fine. 

A Frozen Heat Pump In Summer

Yes, you read that right. Even if the blisteringly hot summer months you can sometimes end up with a frozen heat pump.

You may wonder why this is. The answer is that low refrigeration levels can cause the freeze. 

Basically, this means that the chemical in the pump absorbs heat and turns it into cold air through compressors and evaporators.

If you do find yourself with a frozen pump in the summer months, you’re going to want to use the defrost mode mentioned above.

If you’re unsure of how to set it to this mode, always refer to your manufacturer instructions or manual. You’ll need to do this as setting the mode will differ in execution from model to model. 

Best Way To Avoid The Inconvenience 

Let’s face it, the last thing you want is your heat pump to break down during the coldest months when you need it most. So the best way to avoid all this is to follow these helpful tips

  • Keep up to date with maintenance 
  • Service your unit regularly 
  • Clean it often
  • Consult a technician if you suspect any major damage 

Final Thoughts

You can certainly run a heat pump once the temperature drops below freezing. However that isn’t to say that you won’t always bump into a few issues once the colder months hit. 

Modern pumps will certainly perform more effectively than those with a little time on their side.

Older pumps may hit a few more bumps along the road but hopefully, this article has given your the tools to combat any struggles you may face. 

It is really vital though to keep up with the upkeep that your heat pump (see also ‘What Is A Heat Pump And How Does It Work?‘) demands because you really don’t want to be left in the freezing cold with no way to get warm because your pump has died.

This is why it’s so important to always follow the rules and advice in your manufacturer’s manual about scheduled maintenance.

Otherwise, you will run the risk of damaging the pump and shortening its lifespan.  

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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