01
First, confirm the pattern
Check the pressure only when the system is cool and note how quickly it falls. A gauge that drops every day suggests a different problem from one that changes gradually over several months.
- Photograph the gauge when cold
- Note whether the pressure rises sharply while heating
- Look for visible water around radiators and exposed pipework
02
Common causes
Pressure can be lost through a small system leak, a passing pressure-relief valve, an expansion-vessel problem or internal boiler components. Water marks are not always visible because a small leak may evaporate on a hot surface.
03
Why repeated topping-up is not the cure
Adding fresh water restores pressure temporarily but does not repair the cause. Repeated filling also introduces oxygen into the heating system, which can contribute to internal corrosion and sludge.
04
What an engineer will assess
The correct next step depends on the boiler, pressure behaviour and system condition. An engineer may inspect exposed joints, the discharge pipe, expansion vessel, safety valve and relevant internal components before recommending a repair.
Need a professional assessment?
Send Atlas Gas the appliance details and photographs where useful, or book a suitable routine appointment.