Boiler losing pressure: what to record

A falling pressure reading is a symptom, not a diagnosis. It may involve the heating circuit or the appliance, and a visible radiator leak is only one possible explanation.

Record the pattern

Note the reading when the system is cool and any change you have already noticed while it runs. Use the manufacturer’s normal operating guidance; different systems have different instructions. Do not assume a pressure target from a generic website.

Explain whether the pressure falls over hours or days, whether heating stops, and whether a fault code appears. An accessible photograph of the display can help communicate the reading.

Look only where it is safe

Visible water at a radiator, valve or exposed pipe is useful to report. Do not lift floors, open a boiler case or reach into wet electrical areas to search for a hidden leak.

If you can see a radiator leak, read radiator leak repairs. If water is escaping from the boiler itself, use boiler water-leak precautions.

Repeated topping up is not a repair

Continually restoring pressure without finding the cause can conceal an ongoing problem. Do not keep resetting equipment or operate filling controls you do not understand. Follow the appliance’s user instructions and seek qualified advice.

Book diagnosis, not a guessed component

Call with your postcode, boiler type and the pattern of pressure loss. Mention any recent work, noises or discharge already observed. The engineer should establish the fault before proposing parts.

Gas appliance work requires the right Gas Safe registration and appliance categories. Check the attending engineer’s details before work begins. Hot-water and heating-related emergencies may require different trades or follow-up work depending on the cause.