BoilerTroubleshooting2026-02-26
Boiler Noisy When Hot Water Runs
Noise during hot-water use often means scale in the heat exchanger or low flow.
If your combi gets noisy only when you run hot water, scale is the likely cause.
Common causes
Scale in the plate heat exchanger causes localized boiling and noise when hot water flows; low flow can add to it.
What to do
Descaling the heat exchanger usually resolves the noise; a water softener slows future build-up in hard-water homes.
Key takeaways
- Noise on hot water = scale
- Descaling usually fixes it
- A softener slows build-up
- Don't ignore worsening noise
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