Boiler doesn't hold pressure after temporarily removing radiator

[Agsy]

So we took a radiator off the wall on the weekend in order to paint the wall. Turned off TRV and lockshield valve, drained the water from the radiator etc. Capped off the TRV but it appears that it still kept leaking through the cap (I guess the valve doesn't close properly, never seen that before). We've done this before with other radiators and never had a problem.

Sorted the wall, put the radiator back, reconnected and filled (bleeding the valve when needed). Pressurised the system and all seemed ok, no apparent leaks. Except now the boiler (Baxi Platinum+ 40) doesn't hold pressure. If we fill it to 1, it'll drain fully in around 4 hours. Can't find evidence of leaks anywhere. The potentially leaky TRV mentioned earlier is fine. No indication of anything coming out the PRV. Seems very coincidental that it happened when removing/replacing the radiator.

Any ideas?

Thanks!

 

[terryplumb]

As the two pipes (going to the radiator that was removed) have been disturbed ,they would be the first thing to check ,including any joints that you can't see ( under floorboards etc).
It doesn't take very much water loss to reduce system pressure from 1 bar to zero.
It is ,of course, quite possible that rad removal is a coincidence and water loss is elsewhere ,but on the balance of probabilities It's far more likely related to that rad or its pipework

 

[Agsy]

Hey, thanks for the quick reply. It was the response I expected but didn't want! The radiator is in the middle of flooring that is difficult to remove! It's in a new extension and the only radiator with flexible plastic piping coming out of the wall, hopefully that makes it easier to check (we can cover any small new holes hidden behind the radiator.

Thanks!