Heat Pump Noises You Should Not Ignore

If your heat pump is making some concerning noises, you should consider a few things because your heat pump may need some service work. Heat pumps are not considered to be loud devices so if you are hearing loud noises, you cannot ignore it. Normal sound levels emitted from most heat pumps range between 40 and 50 decibels. That is less than a working dishwasher or a light rainfall.

Heat pump sounds rarely go away on their own. In fact, they tend to get worse over time if they are left untreated. Keep reading to learn the normal vs concerning noises and what they might mean.


What is a Heat Pump and How Does it Work?

Heat pumps are essentially two-way air conditioners. In the summertime, they work like any other air conditioning unit, removing heat from the air inside and pushing cooled air back into the home. In the cooler months, they do the opposite by drawing heat energy from the air outside and moving it into your home to warm things up. The process is especially efficient, using half as much energy on average than other electric home-heating sources.

The biggest difference between heat pumps and traditional heating and cooling systems is that they are designed to be ultra-energy efficient. This is because heat pumps only move heat, instead of generating it by combusting a fuel source. The system requires an outdoor and an indoor unit (unless using the less common geothermal system), which work together to suck up hot air and introduce it to an inside space or expel it outside.

During warm days, a heat pump moves the uncomfortably hot air out from the home and transfers it to the outside environment. And on cooler days, the heat pump transfers warmer air from outside and pulls it into the home to warm it up. They also provide homeowners with humidity control and air conditioning.

Heat pumps are suitable for areas with moderate cooling and heating needs. So, in the battle between a heat pump vs. an HVAC system featuring a furnace or a boiler, space conditioning costs less with a heat pump in temperate climates.


Learn Your Heat Pump’s Normal Operating Sounds

If you are a homeowner, it is important to familiarize yourself with the typical noises your heat pump makes when running. That way you are alerted early if you start hearing sounds you do not recognize coming from your heat pump system.


4 Normal Heat Pump Noises

Before we get started on some of the heat pump noises that you really have to worry about, let’s first go over some common heat pump noises that are indicative of a properly running heat pump

  • Startup and Shutdown Noises

When your heat pump starts up and the fan kicks in, you might hear a rattling noise. When the compressor kicks on and compresses the refrigerant for the next cooling cycle, you will hear a slight vibrating noise. These noises should cease after a few minutes, dependent on where your heat pump is in the cooling or heating cycle. These should not be loud noises but normal operating noises that should be consistent over time.

  • Defrost Mode

During the heating process, cool air is generated around the evaporator coils. Since it is cold outside, the coils can develop frost or ice build-up, making the unit less efficient. The heat pump senses this and automatically switches to defrost. The whooshing or swooshing sound that accompanies the switch to the defrost mode can seem loud and may last several minutes.

  • Gentle Humming/Buzzing

Don’t be alarmed if your heat pump makes a gentle humming noise as it operates. A gentle humming noise usually means your system – including the compressor and motor – is operating as it should. You may also hear a buzzing-type sound from the AC contactors and coils when electricity runs through them.

  • Fan Motor Noise

Air is the key to how your heat pump transfers heat into and out of your home. This air movement is created by a large fan located at the very top of your heat pump. When it runs it can be a little noisy but should be nothing that is bothersome. The noise your heat pump fan produces should be consistent, smooth and not overly loud. You may also hear a click just before your heat pump fan comes on.


Heat Pump Noises You Should Not Ignore

Heat pump systems are known for operating quietly, but they are likely to still create some noise. This does not mean that every sound is normal to hear. Make sure that you listen for any of these noises that indicate trouble:


  • Rattling

If you are hearing the sound of something shaking around the inside of your heat pump, you could have a loose part within your system that is vibrating or shaking around in its housing. Any large debris that gets trapped inside your air ducts can make a rattling noise too as it bounces around in them. Having your filters properly in place at all times should prevent debris from being sucked in the ductwork but not always.

  • Screeching

Do you have to cover your ears every time you turn on the HVAC system? Often, the noise arises if a metal scraps against another. It is not normal; your heat pump should never produce such noises. This noise is often described as a screeching, squealing, or even “screaming” sound. These are all indicators that there is a problem with metal grinding against metal in your heat pump. This may mean you have a fan blade coming loose and scraping around its housing or it could mean you have a blower motor belt that needs to be lubricated. Whatever the cause, the sooner this sound is dealt with the better. Over time this will ruin either the fan blades or the fan motor itself. Not to mention this noise will probably be so loud it will annoy you even inside your home.

  • Hissing

Do not mix up the sound of hissing with the whoosh of air that you are meant to hear from your heat pump system. Hissing is that sharp escape of air that your system may emit when it is forcing air through a clogged filter. The most common cause of a heat pump hissing noise is a refrigerant leak. As the refrigerant escapes through a small opening created by the leak, it transitions from a high-pressure liquid to a lower-pressure gas, resulting in a distinct hissing sound. Your heat pump will not run efficiently or provide proper levels of heating and cooling when there is a refrigerant leak, and a technician should be called immediately.

  • Gurgling

Your HVAC system uses a refrigerant to cool and heat your home. The refrigerant might develop some air bubbles causing a gurgling noise. In order for your heat pump to work properly, this refrigerant level has to remain fairly constant. Small leaks in the pressurized lines in your heat pump can cause refrigerant loss over time. As the refrigerant line leaks and oxygen gets into the line, it may create a bubbling or gurgling sound.

  • Loud Humming or Buzzing

Last but not least, you may hear the sound of humming or buzzing coming from the heat pump. This is a normal sound, but.

Unlike the gentle humming we discussed earlier, an unusually loud humming coming from inside your heat pump is not normal. This will most likely be caused by an electrical issue in your system such as an electrical disconnect. A seized fan motor will also create a very noticeable loud humming noise.

  • Vibrating

Any vibrating sound coming from your heat pump is not a good sign. Vibrations do such things as loosen screws and nuts on bolts. If left uncorrected for long periods of time, vibrations can even cause much bigger part failures. The louder the vibrations the more serious they are.


Heat Pump Noise Reduction

There are a few things you can do to reduce the noise your heat pump makes. Heat pumps have an average lifespan of 10 to 20 years. If your unit is older than that, it will become louder as it ages. Having regular maintenance will help extend its lifespan and prevent loud noises.

New heat pumps are equipped with these features to reduce noise:

  • Variable speed fans and compressors
  • Soft start and stop functions
  • Nighttime/low sound modes
  • Insulated compressors


Regular Heat Pump Maintenance Is Always Recommended

To keep your heat pump running efficiently, it is important to perform regular maintenance. This includes changing the air filter, cleaning the blower and burner, and checking the thermostat and other components for proper operation. Regular maintenance not only helps keep your heat pump running smoothly, but it can also help prevent breakdowns and extend the life of your heat pump and furnace.

Unusually high heating bills, excessive heat pump noise and the need for frequent repairs can all be signs that maintenance is overdue. To avoid these issues, it is best to get in the habit of doing furnace maintenance at least once a year — even more frequently if anyone in your home has respiratory issues.

So, when is the best time to take care of your annual heat pump maintenance? Our suggestion: shortly before you expect to need your furnace. The end of summer or early fall will usually give you enough time to make sure everything is working as it should and to fix anything that needs fixing so your heat pump is ready when the winter chill kicks in.



Give Us a Call

At Aire-Tech, we can help keep your home at the optimal temperature! We give you countless resources to help you explore and learn about HVAC options, including incentive programs. We work closely with agencies to pass on savings programs and information to our valued customers.

If your system needs repair or inspection, call Aire-Tech on 951-926-1002. You can also visit our Contact page and complete the contact form.