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Plumbing

Losing pressure daily, no leaks and not the expansion vessel.

Anonymous user 23/02/2024 - 2.59 PM

We have a 12 month old Vaillant system boiler that for the past week has been losing pressure (1.4 - 0.4) over the course of about 8 hours. We have checked the expansion vessel and that it sound. We have isolated different routes for the pipes and apparently that has not yielded any clues. There are no obvious leaks (staining or water anywhere) and we have checked pipes and rads everywhere. We have also checked the outlet pipe and there is no sign of anything being let out. Does anyone have any idea what this could be or what we should do now? We have isolated the boiler and the pressure stabilised so I'm assuming it's not our brand new boiler.

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2 Answers

Anonymous user

You say that your boiler is quite new did it replace a open vented heating system.which many open vented systems operated at a lower pressure the increase pressure of a system boiler does cause leaks .Which your leaks may be below floor level .which is difficult to find .One could try to increase the boiler pressure to nearly maximum pressure just under 3bar providing the mains water pressure can reach that,Do this after the boiler has been running then go round looking at all radiators, valves and pipework.Including the pressure release valve pipe which should be external Also look at the ceilings for staining.You also may have drain cocks on the outer walls of your building so check them if you have them.if all fails their is a leak sealant that can be put in to system which may hold the pressure.However it best to find the cause and rectify Ps you may have an automatic air vent letting by that may not be be accessable ie loft, old cylinder cupboard, top of boiler Dave Gas engineer /plumber

Answered27 October 2015

Anonymous user

You say that you have isolated the boiler & the pressure stabaliased ? Also you say that it is a brand new boiler ? How new ? If it has only just been fitted, and chemicals were introduced to clean the system, then they may not have been flushed out fully . The new appliance will contain an automatic air vent, which if gas / air passes, will drop the system pressure , this is normal ! Please provide more information on how new the installation is. Adrian Southsea plumbing

Answered27 October 2015