Why was this air source heat pump so noisy?
A newly installed air-source heat pump domestic central heating system immediately generated noise complaints abut low-frequency sound from a neighbour. The owner contacted us and subsequently provided the requested smartphone video clips (as per the recommended diagnostic proceedure) of the noise:
- at the neighbour,
- close to the units
- inside the adjacent garage
This allowed us to rule out structure-borne noise (a common noise issue for A/C and heat pump installations) and to diagnose that the cause of the noise problem was primarily sound reflections that created an amplified 93Hz pumping frequency due to standing waves.
How was the heat pump noise reduced?
This precise diagnosis coupled with the photos provided, allowed us to devise a simple solution involving low-cost components available in DIY stores (plywood and loft insulation). Once installed, these noise control measures broke up the standing waves and reduced the tone at the neighbour by about 30dB (as shown in this noise signature), eliminating the problem.
This was a fast, low-cost project completed remotely (without any site visits) via the supplied smartphone data.
We have provided a more detailed guide to heat pump noise reduction covering both air-source and ground-source noise control.
