Pressure loss - not sure why

[Robin37]

Hi everyone. I'm hoping someone can help please.

Recently a pipe came off one of our radiators (long story!), water everywhere - but not all the water in the system came out. Pipe fixed, no more leak. Had to top boiler up a couple of time, understandable.

However, we have kept experiencing pressure loss - goes from 1.0 bar to .8 bar over a week, consistently. Pressure gauge is not going high and can't see any water coming out of outlet pipe. Radiators have been bled.

I know the obvious answer is - there's another leak, but, the boiler (Gas combi) had worked perfectly for the entire 18months prior(new install), no pressure loss, nothing - until this recent leak. I've checked all valves for leaks, no patches on ceilings. If it is another leak it's a huge coincidence.

Just wanted to ask for some advice on here before getting someone out, so I have a bit of of knowledge behind me.

Thanks in advance.

 

[mcmoby69]

Aav inside the boiler could be weeping. (if it has one) heat inside the boiler evaporating the drip away before it shows outside the boiler casing.
Absolute guess

 

[Robin37]

Thank you, it's one thing to get an engineer to check out. I'll see what others respond with too

 

[Dan Robinson]

0.2 is nothing. Does it continue to drop below 0.8?

 

[Robin37]

Yes, if we don't top it up it will keep dropping, it doesn't hold at .8.

 

[jeff the gasman]

You've got a leak then.

 

[Robin37]

Thanks for replies. I was so hoping it's not a leak. As if one wasn't bad enough! Might have to be an insurance job to find it I think

 

[simond]

Did the person doing the repair use the boiler prv to drain the system? If so it is probably dribbling out of the pressure relief valve.

 

[Robin37]

No, the system was not drained when original leak occurred. Pipe came off, dumped water everywhere and then stopped (does a vacuum/airlock form somewhere? Not sure of this), pipe re-attached and system re-filled from filling loop

 

[simond]

Youve got a leak then. As Jeff says.....

 

[Robin37]

Thanks for your input everyone, much appreciated. I just wanted to rule everything out before going down the leak route

 

[Robin37]

An update - after much searching, plumber found the leak - was a pinhole from old copper pipe dripping onto main flow pipe which was drying it up - thus no ceiling mark! All fixed now and hopefully that's the end of it.

Thank you for all your help