BoilerTroubleshooting2026-02-26
Hot Water Not Hot Enough: Causes
Lukewarm water often means scale, a stuck diverter valve or a low temperature setting.
Weak or lukewarm hot water from a combi usually traces to scale or a valve.
Common causes
Scale build-up in the plate heat exchanger, a partially stuck diverter valve, or a low temperature setting reduce hot-water performance.
What to do
Raise the setting first; if water stays lukewarm or fluctuates, descaling or a diverter-valve repair is likely needed.
Key takeaways
- Check the temperature setting
- Scale is a common cause — descale
- A stuck diverter valve reduces heat
- Fluctuations point to scale
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