A one-off pressure change and a reading that falls repeatedly are different situations. Persistent loss can point to a leak, discharge or component problem that needs proper investigation.
Observe the pattern
Write down the pressure when the system is cold and how quickly it changes. Look only for visible water around radiators, exposed pipework and the boiler without removing panels.
- How often pressure needs attention
- Whether it rises sharply when heating runs
- Any visible drips or damp areas
- Recent radiator bleeding or system work
- Any fault code shown at low pressure
Avoid repeated topping-up
If the manufacturer’s user instructions explain safe repressurising, a householder may be able to restore pressure once. Repeatedly adding water can mask the cause and is not a repair.
Request an investigation
An appropriately qualified engineer can assess the full sealed system and explain the repair options. Mention any leak immediately and keep away from affected electrics.
Important: This guide provides general information. Do not remove a boiler casing or attempt gas work. Follow the manufacturer’s instructions and use an appropriately qualified Gas Safe registered engineer for gas work.