The hum of heat pumps can be very annoying and with the recent push to install them, more and more people are being adversely affected – even when legal noise limits are met. This low frequency noise can be particularly challenging. It is best captured as the tonal quality of the noise. The following is a summary of the recommendations from a recent article in the Building Biology Magazine:
How to reduce the noise of air source heat pumps:
- Low-noise units have a sound level of 55 dB (< 6 kW) and 60 dB (6–12 kW) according to the German Environment Agency.
- Location of outdoor units
Sufficient distance from your own home / your neighbors’ homes, preferably on the side of the house away from bedrooms or other noise-sensitive areas
Installation of outdoor units
Installation surface: Soft surfaces such as gravel, grass, or bark mulch are preferred. Hard surfaces such as concrete, tile, or asphalt produce more noise.
Foundation mounting: Use vibration isolators or rubber anti-vibration mats.
Surrounding surfaces: Cover sound-reflecting walls/components near the unit with sound-absorbing materials. (Does not help against low frequency noise.)
Refrigerant and water line connections: Choose flexible piping. - Additional sound barriers can range from a sound barrier in front of the outdoor unit to a complete sound enclosure with anti-vibration mounts.
- Control settings: Turn down the heat pump at night to minimize noise. For radiant systems, add a buffer tank.
Find out more (in German)
Learn more about measuring the tonal quality of noise