Central Heating Leak

[10051550]

I have a Danesmoor 15/19 oil fired boiler - the central heating works OK but I've noticed that the pressure reading drops from 1.5 bar to .25 bar following the heating being on for some time - on further inspection I have water on the floor in the garage around the boiler

I suspect either the PRV on the boiler has failed OR the pressure vessel in the airing cupboard has failed is causing the PRV on the boiler to trigger

My questions are ;

1. Is it likely to be the PRV or the Expansion vessel that has failed ?

2. The Expansion vessel is a 12L varem , I notice most suppliers pre-charge to 1 bar but this has 0.5 bar written in the pre-charge box on the label - can you get different pre-charge values and would it matter if I use a 1 bar ?

 

[Whitespirit66]

If the PRV was discharging, it would be coming out of the PRV pipe. Surely you pipe discharges outside, not under the boiler?

Sounds more like a leak from inside the boiler.

 

[10051550]

OK brain now fully engaged

The PRV ( while the manual states internal ) is actually 6 inches above the boiler venting through the garage wall and is dry as a bone.

So the leak must be inside the boiler - but only leaking when heating charges to 1.5 bar , if left at 0.75 it will not leak

Any ideas - could the expansion vessel causing the issue ?

 

[Whitespirit66]

Doesn't sound like exp vessel problem. Could be a weeping seal, that leaks at higher pressure.

If you could whip the boiler's cover off, see where it's coming from, and get the camera out, someone on here could give you an idea of the cause.

 

[10051550]

So here's where I'm up to

Heating pressure dropped overnight - checked pressure vessel ,it's 0.5 bar / 7.5 psi which sounds about right - so I'm excluding this from the troubleshooting


Can't visably see where the leak is coming from except it's at the rear of the boiler as this is where the floor is wet - I've cranked up the pressure back to 1.5 bar and had heating on for 2 hours - no sudden spikes on pressure gauge and no drop in pressure when switched off.

Gonna be tougher than I first thought

The only other strange thing I've noticed is a tinkle-ing sound from the pressure vessel when the pump is on full belt - like a ball bearing bouncing around ?