How Noisy Is Noisy When Buying a Heat Pump?

Indoor unit noise level

Good question: what is noise?

Noise technically is a vibration of particles transferred through a media. In our case air, but anyone who has dived or done work under water will know how well noise travels through the water medium.

There are many ways of measuring noise, sound level, sound power, pitch, frequency, reverberation. When we are comparing one heat pump to another we generally use the term decibel which is a sound power measurement. This unit was of course invented by Alexander Graham Bell who gave us among many things, the telephone.

Quiet Indoor Unit

The key thing to remember when we are talking about sound measurements in decibels is that it is a non linear or logarithmic calculation. For example for every 3 db increase in sound level we are increasing the sound level by 50% and for every 6 db we are increasing the sound level by 100% or doubling the noise. So when a customer is comparing say a 20 db indoor unit to a 26 db  indoor unit then that unit is in fact twice  the noise approx.

Careful attention to both indoor and outdoor noise levels as well as a heat pump’s ability to deliver  useful heat at low ambient conditions should be a primary purchasing decision.

Tonal noise

Tonal noise is also another problem with outdoor units especially at night where there is little or no background noise. Acceptable boundary noise levels during the day vary from 50 db to 60 db during the day down to 35 db at night depending on the local authorities.  Where it is quiet at night, high pitched tonal noises seem to travel further and these tend to come from outdoor units that operate at high compressor frequencies and struggle at low ambient temperatures that occur at night.   Outdoor unit location is always an important factor. Your local authorised installation company or manufacturers technical support team will be able to assist in this area.

Noise is an important consideration when purchasing a heat pump.