Thermona
Chronic Pressure Loss
Boiler frequently loses pressure and needs topping up every few days.
Advertisements
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.
Advertisements
Possible Causes
Small leak in heating circuit radiators or pipework, Leaking Thermona expansion vessel diaphragm, Dripping pressure relief valve, Micro-leaks on boiler hydraulic block
How to Fix / Troubleshooting
Safety: Do not repeatedly overfill the system above the recommended pressure. This can damage components.
- Visual leak check: Inspect all accessible radiators, valves, and visible pipework for damp patches, green staining, or rust marks.
- Check PRV discharge: Look at the pressure relief valve discharge pipe outside. If it is wet or dripping, the PRV may be passing water.
- Expansion vessel test (engineer level): With the system depressurised, measure the air charge in the Thermona expansion vessel. Recharge or replace if the diaphragm has failed.
- System leak test (engineer level): A technician can pressurise the system with air or use leak detection fluid to locate hidden leaks.
Advertisements
Repair Difficulty
Medium
3/5
Required Part
Pressure Relief Valve
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements