A pressure gauge that keeps dropping below 1 bar is telling you something. Here's what we check first on Sussex call-outs.
If you're topping the filling loop up every few weeks, water is escaping somewhere. Pressure doesn't vanish on its own, it either leaks out of the pipework or is pushed out through the pressure relief valve.
The three most common causes we find are a leaking radiator valve or towel rail joint, a failed expansion vessel inside the boiler, and a passing pressure relief valve that dumps water out through the discharge pipe outside.
Start by checking every radiator valve and the pipework under floorboards near the boiler for damp patches or staining. Then look for the small copper pipe leaving the boiler and exiting through an outside wall, if that's dripping, the valve or vessel is the likely culprit.
An expansion vessel can often be re-pressurised rather than replaced, which is a far cheaper visit. If yours has failed completely we can fit an external vessel instead of stripping the boiler down.
Whatever the cause, don't keep repressurising indefinitely. Repeated top-ups introduce fresh oxygenated water into the system, which accelerates corrosion and sludge build-up in your radiators.
