How Noisy Are Air Source Heat Pumps? We Tested One
One of the questions we are asked most often is ‘How loud are air source heat pumps?’ and the answer we always give is ‘not as noisy as a gas boiler!’
But that’s not very scientific and can come across as a sales pitch.
So, we sent one of our fitting teams to the MD’s new house ... where we have just fitted a Samsung ASHP ... with a sound meter and some notebooks.
Before we get to the results, we’ll just give you the lowdown on air source heat pumps in general.
What Is an Air Source Heat Pump?
It’s a reverse air conditioner – sort of.
It’s a little more complicated than that, but the principle remains the same.
Air is passed over refrigerant to change it’s temperature.
In an ASHP, the external fan draws air into the system, this is then passed over pipes filled with refrigerant to increase the refrigerant temperature.
Once heated, the refrigerant is passed through a high-pressure system to increase the temperature even more.
Once at the correct temperature, the refrigerant filled pipes will heat the water in your central heating system.
To find out the proper ins and outs of a central heating system that utilises an air source heat pump, check out our ‘What is an Air Source Air Pump?’ blog.
Why Noise Matters with Heat Pumps
Honestly, no idea!
Obviously, it’s important that you don’t have something outside your house rattling around at deafening volume, but heat pumps have never done that.
We feel the concern over volume may be connected to old school technology and the bad rep that air conditioning gets - plus some bad actors in the press spreading misinformation.
It's the external fan that makes anoise and, in an average system, that noise is about 40 – 60 decibels.
For reference 40 dB is totally acceptable in a library and 60 dB is the level of a normal conversation.
The big reason to worry about the noise of an ASHP is annoying the neighbours.
The legal limit, taking a reading from the neighbour’s property, is 42 decibels – which is about the same volume as your fridge if you stand next to it.
Testing Setup: How We Measured the Noise
So, we arrive at the MDs house early on a cool morning in April.
We took the decision to arrive at the same time the family is starting to stir, the heating is kicking in and everyone’s fighting to get in the bathroom.
That way, we know the heat pump is working hard to keep everyone warm and showered.
We knocked on the neighbour’s door, bearing in mind these properties are detached, and asked if we could set the sound level meter on their patio.
Once we were set up we returned to the MD’s garden and popped a sound meter next to the heat pump fan itself.
Noise Levels: What We Found
Our first conclusion was that the MD was in no danger of being arrested by the noise police.
The neighbour’s garden was no nosier than it would be without the heat pump next door, registering about 30 – 35db, which is more or less normal for a suburban street.
Back in the MD’s garden, and stood next to the air source heat pump fan, and the meter was only just touching 42dB.
Comparing Heat Pump Noise to Everyday Sounds
As we’ve said previously in this blog, an air source heat pump should function at around the same level of noise as your fridge.
These things also make the same amount of noise as an air source heat pump fan:
· Refrigerator hum
· A quiet office
· Quiet a quiet residential area
· Light rain
· Whispering
Basically, not very noisy at all.
Factors That Affect Heat Pump Noise
If your air source heat pump fan starts to make a bit of a din, there is probably something wrong with it.
Obviously, parts can start to wear out and cause the fan to spin incorrectly. This would create a ‘rattling’ kind of sound at first.
If you hear this, contact your installer immediately as it will ony escalate and could damage other parts of the system.
A noisy fan may have debris or grit in it, so a quick service will sort the problem out in no time.
Commercial heat pumps, or over-sized ones, will be nosier than a domestic model, but these are usually installed in non-residential areas and only used during working hours.
Older fans will also be nosier than their more modern counterparts.
Tips for Reducing Heat Pump Noise
You really shouldn’t need to reduce the sound of your heat pump BUT if you have a very sensitive neighbour or something, here are few things you can do to reduce noise.
Regularly servicing or cleaning your fan unit will keep it quiet.
So, that's replacing filters, ensuring all the fittings are secured correctly, and removing any debris and rubbish from the immediate area.
If you are still worried about noise, then a simple barrier or acoustic baffle can be fitted around your fan unit, but make sure not to restrict any air flow to the fan.
Final Thoughts: Are Air Source Heat Pumps Too Noisy?
We think, with our experiments and the data available, we can conclude that air source heat pumps are not noisy at all.
And, if they are, there is most likely a problem with the fan unit, the install or the amount of debris blowing around your garden!
In fact, the only noise air source heat pumps are generating is from the naysayers in the media and or anyone trying to sell you a gas boiler.
Air source heat pumps are efficient, reliable and quiet.
