TrevorP wrote on Oct 31st, 2016, 11:41am:Few months back had new boiler and tank fitted, as weather fine did not require heating until now, but find the pressure constantly dropping, as much as 0.6bar per day.
I have checked all rad valves, boiler safety, vent, and any signs anywhere for a leak, but found none.
Am now suspecting an under floor leak, but the downstairs flooring is an asphalt screed, so my problem is finding it, has anyone any ideas? as I cannot see any damp patches yet.
Also have found that the pipework to radiators in the asphalt is not lagged, is asphalt corrosive to copper, as concrete?
Any advise appreciated.
TP
Lastly, apply lateral thinking.
Ok you don't say whether you used the boiler to heat the tank or not, but lets assume you did and the pressure was constant blah blah etc.
Now the problem I have, is it's the same water heating the tank as the radiators so whats changed. ? nothing, so what have you done to get the radiators hot. 0.5 bar is probably a bottle of water depending on the size of the system, nothing more than a weep on a rad valve or nut.
You should be checking every nut, fitting, pipe insight when the system is cold, it is also common for a leak to be internal to the boiler or something the rgi has done as new work.
Don't waste time and money chasing shadows, isolate the boiler, if the pressure hols over night open the valves and see whether it drops instantly.
Is the cylinder new, the coil could be pinholed or damaged and the water is going into the storage tank. Is the stored water hot/warm if not used overnight.
Lots of easily checkable jobs before you even think to look ander the floors.