BoilerTroubleshooting2026-02-26
Low Hot-Water Pressure from a Combi
Weak hot-water pressure can be scale, a partially closed valve or low incoming mains.
Low hot-water flow from a combi traces to scale, valves or your mains supply.
Common causes
Scale in the heat exchanger, a partially closed isolation valve, a clogged inlet filter, or low incoming mains pressure reduce flow.
What to do
Clean the inlet filter and aerators and confirm valves are open; descaling addresses scale-related flow loss.
Key takeaways
- Clean the inlet filter and taps
- Confirm isolation valves are open
- Scale reduces hot-water flow
- Mains pressure can be a factor
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