Boiler Pressure FAQs
Why is my boiler pressure too low or too high? How to repressurise your boiler safely.
5 questions answered by our Gas Safe engineers
What pressure should my boiler be at?
Most boilers should sit at 1–1.5 bar when cold. When the heating is running it may rise to 1.5–2 bar — this is normal.
Why has my boiler pressure dropped?
Boiler pressure can drop due to a small water leak in the system, a faulty pressure relief valve, or from bleeding radiators. If it keeps dropping, call a Gas Safe engineer.
How do I repressurise my boiler?
Locate the filling loop (usually under the boiler — a braided hose with valves). Open both valves slowly until the pressure gauge reads 1.5 bar, then close the valves. If you're unsure, contact us.
What happens if boiler pressure is too high?
If pressure exceeds 2.5–3 bar, the pressure relief valve will release water outside. This is a safety feature. Bleed a radiator to reduce the pressure or call an engineer.
Why does my boiler keep losing pressure?
Recurring pressure loss indicates a leak or a failing component. Common culprits are the pressure relief valve, radiator valves, or a pinhole in the pipework. Have an engineer investigate.
Still have a question?
Our Gas Safe engineers are happy to answer any boiler questions. Call or message us.
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