Why is my boiler losing pressure?

What the pressure reading means

Many sealed central-heating systems show pressure on a gauge or display. The correct range depends on the boiler and system, so use the manufacturer's instructions rather than a generic target. The reading may rise as the system heats and fall as it cools.

A one-off change after radiator bleeding can be different from repeated pressure loss. Frequent topping up is not a lasting fix and can hide a leak or underlying fault. Keep a note of cold readings and how often they change.

Safe checks around the home

1. 1Check the boiler display and manual for the correct cold pressure and any fault code.
2. 2Look for dampness or drips around accessible radiator valves, pipe joints and the boiler exterior. Do not remove covers or touch hot components.
3. 3Notice whether pressure falls when the heating is off as well as when it runs, and record the pattern for the engineer.
4. 4If you see water near electrics, keep clear and turn off electricity at the consumer unit only if safely accessible from a dry area.

Possible causes and next steps

A leaking radiator valve, pipe joint or concealed heating pipe may let water escape. A recently bled radiator can also lower pressure. Repeated rises when hot followed by low pressure when cold may point to a component problem that needs diagnosis.

Boilers contain gas and electrical components. Do not open the casing, adjust internal parts or attempt repairs. Any gas work must be carried out by a Gas Safe registered engineer. TraceFix can investigate accessible plumbing leaks in Birmingham and London and explain when a heating specialist is needed.