Modern air source heat pumps are significantly quieter than older generations. Most domestic units run at around 40-45 decibels measured at close range — roughly the level of a quiet conversation, or a fridge humming in a kitchen.
What affects real-world noise isn't just the unit's rated figure. It's:
- Where the outdoor unit is sited — we avoid placing it directly under bedroom windows or against reflective walls that can amplify sound
- How it's mounted — vibration absorbers and a solid level base stop low-frequency drone from travelling through the wall
- Distance from the nearest neighbour's window — MCS installation standards require a formal noise assessment (MCS 020) before sign-off, and we complete this on every install
- Defrost cycle — in cold damp weather the unit briefly defrosts its coil, which is slightly louder for a short time
Under the MCS 020 standard the unit has to stay below 42 decibels at the nearest neighbour's window. We design every install to meet that and document it as part of the paperwork under JME Green Energy's MCS certification.