Are Heat Pump Water Heaters noisy?

Are Heat Pump Water Heaters noisy? Heat pump water heaters do make some noise, but generally, a modern, well-made unit will not be unbearably noisy when it’s installed properly. They’re a lot different from a standard hot water cylinder or immersion heater, so some amount of operating noise is unavoidable. The sound level of a heat pump water heater is more comparable to a fridge or air conditioning unit than a boiler firing up. As for the sound, it depends on the model, fan speed, compressor design, installation location, usage frequency, and vibration control.

Why are Heat Pump Water Heaters so noisy?

An air source heat pump water heater uses a refrigeration cycle to suck heat out of the air and move it into your domestic hot water.

The two main culprits of noise are the compressor and fan.

The compressor is the bit that cycles the refrigerant around the refrigeration system, raising its pressure and temperature in the process. This can make a low humming or buzzing sound when the heat pump is in use.

The fan draws air across the evaporator, allowing the refrigerant to absorb heat from the air. The air moving through the appliance itself, through any connected ductwork and grilles, makes more noise.

Other bits like the refrigerant flow and condensate drainage can make some noise, but usually it’s just the compressor and fan that you can hear.

For product specifications and further information, please explore our dedicated air source heat pump water heater ranges:

Wall mounted heat pump water heating systems
Domestic heat pump water heating systems
Commercial heat pump water heating systems

Just how loud are heat pump water heaters?

There is no such thing as a one-size-fits-all figure when it comes to the noise of a heat pump water heater.

Depending on the model, what it’s doing and how the measurement was taken, manufacturers often quote noise figures in the 40 to 60 decibel range. However, you have to compare these figures carefully because manufacturers might quote the sound power level or the sound pressure level, and these two aren’t the same. How loud it sounds also depends on a load of other things like how close you are to the appliance and how good your room is at absorbing sound.

When comparing different heat pump water heaters, check what sound measurement the manufacturer is using and what conditions it was measured under.

Where should a heat pump water heater go?

Where you put it is pretty important when it comes to whether you can even hear it.

If you put a heat pump in a decent utility room, garage, or plant room, then it’s probably going to cause very little disturbance. On the other hand, if it’s right next to a bedroom, it’s going to be a lot more noticeable, especially if it starts running at night.

Grey surfaces like concrete and brick can make sound bounce around, but if the pipework and fixings aren’t properly isolated, then the compressor can vibrate its way into the building.

So installation needs to take into account both the airborne noise and the vibrations that can be transmitted through the building.

Can ducting make heat pump water heaters even noisier?

Yes, it can. It’s particularly bad if the ducting is rubbish.

Some heat pump water heaters allow you to duct the intake air, the exhaust air or both. This gives you a lot of flexibility in where you put the appliance, but you need to make sure the duct system is good enough. Ducting that is too small, has too many bends or is blocked can make the airflow noise worse or even reduce how effective the heat pump is at getting the heat out of the air.

If you size and install the ducting properly, you can steer the air (and some noise) where you want it to go.

Is a noisy heat pump water heater broken?

Not always. If the fan is humming away or the compressor is buzzing, then that’s all pretty normal.

However, if the noise suddenly changes, that’s probably a sign of a problem. If you hear any rattling, grinding, knocking or excessive vibration, then you need to investigate what is going on. The issue could be something as simple as the panels or fixings coming loose or as serious as a mechanical fault.

If the heat pump is noisy and not making enough hot water or is using loads more electricity, then that probably needs looking into too.

Are heat pump water heaters noisier than the old electric hot water cylinders?

Yes, they are. Electric hot water cylinders are pretty quiet because they just have a heating element that doesn’t make any noise and a thermostat.

Heat pump water heaters are more noticeable because they have a compressor and an evaporator fan that makes some noise. But the reassuring news is that they don’t run continuously. Once the hot water tank reaches its target temperature, then they can switch off until more heat is needed.

Getting a tank that is the right size can also help because it means that the heat pump can just recover the hot water that is already in the tank rather than constantly heating new water up.

Should noise be enough to put you off getting one?

For most people it shouldn’t be. Noise should just be one of the things to consider when you are deciding where to put a heat pump water heater. Consider the manufacturer’s noise level, where you will put it, how often it will run, and how much vibration will be transferred into the building. Choosing a quiet, heat pump hot water system that’s the right size for your home and installing it in a spot that makes sense can get you efficient domestic hot water with minimal noise disturbing the household.