Loss of pressure in unvented pressurised system All aspects of plumbing questions and answers, help, tips and information

[campbep]

I keep losing the pressure in my water system and have had to top up the water to restore the pressure each day for the last three days. Does anyone have any suggestions as to what the problem might be or how I can remedy it. Thanks

[roger196]

Please confirm this is a combi boiler. Apart from checking there are no leaks from the radiator or the pipes leading to them, is the filing loop left connected?

[campbep]

It's not a combi boiler. We have rads upstairs and wet underfloor downstairs. Oil fired boiler. Filling loop is not left connected. Any other info you may need? No visible leaks from the rads but as for the underfloor?

[roger196]

Have you checked the pressure relief valve is not stuck partly open? Look outside to see if it is dripping.
Is it possible to isolate the underfloor pipes, whilst checking the pressure in the rads upstairs. Otherwise you need to isolate the boiler from the pipes and check each in turn. This can be risky if you are not sure what you are doing. If you are in any doubt, call in a professional. Otherwise proceed at your own risk. If the problem is within the boiler, the most likely is a leak between the two sides of the heat exchanger.

Not being present nor having detailed knowledge of your system, advice can only be given in general terms. Plan carefully in advance each step of the investigation, especially what to do if things go wrong. If you are in any doubt, call in a professional. Otherwise proceed at your own risk.

[bobplum]

silly question but if there was aleak in the underfloor heating would you notice it ie depending on floor coverings?