Hoval
Chronic Pressure Loss
Boiler frequently loses pressure and needs topping up every few days
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Leaking system pipework or radiators, Faulty expansion vessel (loss of air charge), Leaking pressure relief valve (PRV), Micro-leak inside Hoval boiler heat exchanger
How to Fix / Troubleshooting
Safety: Do not repeatedly overfill above the recommended pressure. This can damage the system.
- Check PRV discharge: Inspect the pressure relief valve discharge pipe outside. If it drips when the boiler heats up, the PRV is passing and may need replacement.
- Expansion vessel test: With the system cold and pressure at zero (drain if necessary), measure the air charge at the expansion vessel Schrader valve. It should match Hoval's specification (often around 0.8–1.0 bar). Repressurise with a pump if low, or replace the vessel if water comes out of the valve.
- Inspect for leaks: Look for damp patches under radiators, valves, and visible pipe runs. Repair any leaks found.
- If no external leaks are visible and pressure still drops, a technician should test for an internal heat exchanger leak.
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Repair Difficulty
Medium
3/5
Required Part
Expansion Vessel
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