Boiler losing pressure - cant establish where water going..

[iem]

Hi the boiler is olsing pressure, about 1.5 every 8 hours. Checked expansion vessel and flow regulater which are all fine. all radiators are topped up and no air in them. Topped up pressure to 1.5 bar last last and closed flow and return valves on boiler to establish if it is boiler or pipework, checked this morning and pressure still 1.5 bar. Have chased all pipes as none are hidden and all ok cant see any leaks.....anyone any idea why pressure is dropping when flow/return valves open.......all signs point to a leak and at this rate it should be noticable but its not!!

 

[tamz]

Look harder. There is definitely a leak.

 

[cjg]

tie loo paper on all pipes to trv and l/s then check them later if flopped you got a leak on that one !!! if not then it may well be on joint, hope that helps

 

[paulnwales]

thatas a big leak, should be visable best to take a good look using eyes and hands hopefully you will see or feel the wet part on the pipework also check the blowoff carefully. good luck

 

[truemanufan]

Maybe pipes leaking under floorboards down stairs? That way there's prob a build of water that can go un noticed rather than a leak from upstairs

 

[WHPES]

Is it possible to try and narrow it down for example capping off some of your loops or a zone if it is zoned and trying it?

 

[pobsdad]

If it's a problem with the expansion vessel,it will only show up when the heatings on.Tie a plastic bag round the prv pipe and run the heating.

 

[ian macca]

if its a condesing boiler,could be leaking internally inside the main hex and going out through the condensate pipe,had this a few times