Help & Diagnosis

    Why your boiler keeps losing pressure (and how to fix it)

    If you're topping up your boiler pressure more than once a month, something is wrong. The two usual culprits are a hidden leak somewhere in the system or a failed expansion vessel inside the boiler.

    Common causes

    1. Hidden radiator or pipework leak

    Often under floorboards. Check radiator valves, the airing cupboard and the boiler itself for damp patches.

    2. Expansion vessel failure

    The internal vessel loses its air charge over time. A pressure-recharge can buy time but eventually needs replacing.

    3. Failed pressure relief valve

    Look for water dripping from the overflow pipe outside. A PRV that's letting by needs replacing.

    4. Auto air vent leaking

    A common boiler-internal cause. Quick fix for an engineer.

    Try these first

    • Check every radiator valve for damp patches.
    • Check the external PRV pipe (usually visible on an outside wall).
    • Note how often you're topping up — that's useful info for the engineer.

    Still stuck?

    We diagnose pressure-loss faults across Dereham, Norwich, Swaffham, Fakenham and the rest of Norfolk most days.

    Call 07508 207 799