Boiler Pressure Puzzle

[Valkary999]

I have a Vaillant EcoTEC Plus 937 Power Store system.

It was installed in May as part of a house rebuild (detached 4 bed house, 1 bathroom, 1 Ensuite, 1 cloakroom). Since the heating has been used (October onwards), the boiler loses pressure and needs daily refilling (pressure drops from 2.0 bar to 0.5bar in <24 hours so that heating and HW cutout).

The obvious culprit is/was a leak, but nothing has shown up over past 3 months, which given the amount being lost, I'm assuming something should have shown itself by now? (wood floors downstairs are still level and dry, and ceilings still intact upstairs!)

Within a week of the problem starting, the system couldn't be refilled (water flowed straight out), and Vaillant replaced the heat exchanger under warranty - I'm assuming this is just coincidence!?

The PRV has been checked (was OK). Also boiler has been checked by Vaillant and given a clean bill of health. I did isolate the boiler overnight, with no pressure loss. When system/pipework was reconnected, pressure did drop, but can't understand why the leak is not apparent? Any idea how much water is being lost?

Can air be getting in somewhere to cause the problem - If so, how do I test for this or identify it?

All help appreciated!!

 

[gas4you]

If the pressure remained constant when you isolated the boiler, it has to be a leak on the system.

It could be leaking under the wooden floor somewhere but finding a way down through the floor rather than up through the wood.

Was it just a new boiler you had fitted, or an entire new heating system and pipe work?

 

[Valkary999]

It was a complete system (new boiler, new pipework etc). I do think it's a leak in the pipes, but given how much is being lost (1-2 pints a day was suggested by the Vaillant engineer?) I'm surprised it isn't creating a knock on effect on either flooring or ceilings - Is that really possible?

Also if there is a leak in the pipework that is not making itself obvious, what methods can I use to isolate the area of the problem - I don't really want to rip out flooring etc on spec, until I'm sure I know where the issue is. The builders plumbers are at a loss.......!