Unvented heating system losing pressure Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[TahirJogiyat]

Hi Guys

Appreciate some help with my boiler and unvented cylinder system which has been losing pressure fairly rapidly over the last week or so.

To date we have checked the PRV valve, expansion vessel within the boiler and heat exchanger. Yep n addition a visual check of all the pipe work yet still no solution.

Could there be an issue with my unvented system which is causing my boiler to lose pressure? What other checks need to be carried out.

I have lifted a couple of floorboards on the ground floor to see / hear any leaks but still nothing.

Lastly when the engineer initially came he used a couple of bottles of the leak sealant which seemed to solve the issue for a couple of days but as soon as the hot water went on the system started losing pressure and now it loses pressure both with heating and hot water.

Any advice would be much appreciated.

Thanks

[stoneyboy]

Hi tahirjogiyat,
If you have an automatic vent valve is this leaking, it will be located at a high point on your system.
If your unvented cylinder is mains fed you may have to investigate the pressure differential across the heating coil.
Regards S

[plumbbob]

Could be a faulty expansion vessel. Monitor the pressure as the system heats from cold. If the pressure rises by more than a half bar from cold to hot, it is likely the ev.