Why Does My Heat Pump Make a Loud Noise When It Shuts Off? 4 Reasons

Heat pumps are not the quietest contraptions. They can actually make quite a bit of noise, which is typically harmless. If your pump is noisy right after it shuts off, it is likely because of the pressure inside the heat pump. Your heat pump may make noises for a while as the pressures equalizes (only to become un-equalized as soon as it turns back on).

Of course, while some noises are normal, others are not. It can be hard to know when the sounds are standard and when they are not. For this reason, you may want to pay attention to any new or unusual noises that your heat pump makes.

If your pump is always loud when it turns off, then you probably don’t have anything to worry about. However, if it usually doesn’t make a loud noise and suddenly does, then we recommend contacting a professional to take a look at your machine.

There are some common noises that can be corrected at home with little DIY knowledge. If your heat pump suddenly starts making weird noises, here are some common problems that may be occurring.

The 4 Common Reasons Why Heat Pumps Make Noises

1. Banging Sounds in the Grille

Sometimes, you may notice that the air grille is banging when the heat pump turns on or off. Sometimes, it may bang the whole time that the heat pump is running. Luckily, this is a relatively common problem and can be fixed without calling a professional.

Usually, this banging is caused by the air filter on the other side of the vent. For one reason or another, it is being picked up by the air moving through the vent.

Typically, this is a sign that the filter is not allowing enough air to move through it, which is why it is getting moved around. In this case, we recommend switching to a new filter if yours is dirty and older. If the filter is already new, it is possible that it is too restrictive. In this case, you may need to switch to a new type of filter.

To determine if the filter is too restrictive, you can check the MERV score, which lets you know the size of particles the filter catches. If it catches particles that are too small, it may be stopping too much of the airflow as well. When changing filters, choose a new filter with the same MERV rating.

2. Banging Throughout the House

If you notice banging when the system turns on and off that isn’t in one particular spot, your ducts may be expanding or contracting. This is not typically normal, but that doesn’t necessarily mean that it is a bad thing, either. There isn’t much you can do about this problem, but it is good to know that it isn’t a sign of something seriously wrong.

Usually, the ducts will move when they are not properly sized.

3. Banging on the Fan

Sometimes, the fan can become loose and bang against the metal around it. Usually, it is pretty easy to figure out that it is the fan banging. Sometimes, the fan may only hit the pump as it decelerates. Other times, it will always hit the heat pump when it is running.

Often, you can tighten the fan back into place yourself—just be sure not to get it too tight. If you’re concerned, you can hire a professional to do it instead. Usually, this is a relatively cheap and quick fix.

4. Banging from the Compressor

The compressor is in a sealed housing and actually contains many different components. Many of these components are mounted on coils. Sometimes, these springs can wear down over time. Of course, this typically takes years and years of use.

These components can then bang against the housing whenever the heat pump halts and they lose momentum. It can be a scary noise, but it doesn’t mean that the compressor is going to fail anytime soon.

The only way to stop the noise is to purchase a new compressor, which is extremely expensive. Therefore, our recommendation is to ignore the noise as much as possible.

What Does a Heat Pump Compressor Sound Like?

When it is running smoothly, you’ll likely hear a humming or buzzing sound. This is normal and the result of electricity moving through the system, as well as the tiny parts moving around.

As we’ve already stated, sometimes banging noises may occur when the heat pump shuts off. Luckily, these are typically harmless and just the result of worn springs. Many compressors go on to function for years after these sounds begin to occur.

Therefore, just because the banging starts to happen doesn’t mean that you’ll need to replace the compressor any time soon.

Is a Heat Pump Supposed to be Loud?

Heat pumps are not silent. When running, they can make just as much noise as moderate rainfall or a normal conversation. There are some silent models, but these are typically rarer and more expensive, so you typically don’t have to worry about your heat pump making moderate amounts of noise.

In fact, some heat pumps may actually bang and pop without there being an underlying problem. While heat pumps aren’t excessively noisy, there is a lot of room for loud noises to occur.

Luckily, banging can occur without the need for repair. Just because your heat pump starts banging does not mean you need to call a professional.

How to Tell if a Heat Pump is Bad

Since sounds aren’t an accurate way to tell if a heat pump is bad or not, what signs can we rely on?

There are usually several signs that a heat pump is going bad. Typically, these involve the pump simply not working.

Simply put, if your heat pump is not working as efficiently as it once did, you probably need to contact a professional.

Conclusion

There are several reasons that a heat pump may make loud noises. For instance, the fan can become loose over time and bang against the unit as it slows down. Springs in the convertor may slow down, causing components to bang as they stop moving. Luckily, most of these do not mean that your heat pump is going bad. Instead, you may simply need to tighten the fan.

With that said, some sounds do point to something a bit more serious. If you cannot locate the source of the noise after reading our guide, then you may want to call a professional. Furthermore, if your heat pump isn’t working like it once did, then a professional should be called to determine why it is failing.

Featured Image Credit: Palatinate Stock, Shutterstock