Sealed System Install - Take 2

[diamondgas]

Pressure loss is a water leak! You have one somewhere my friend! If the expansion vessel is fully charged and nothing is visible you could try leak sealer. Injected into the system it solidifies on contact with air and , supposedly, seals the leak! Only other possible issue could be a wild card blockage to the expansion vessel! mho!

 

[tamz]

Check the boiler as gasman says. It could be getting through the condensate pipe.
Pressurise it and isolate the boiler for a while. If the pressure remains steady or drops then you know for definite if the leak is from the boiler or system.

 

[cr0ft]

Thanks for all the feedback so far. Heat exchanger leaking through the condensate pipe isn't something I'd considered. As the leak equates to 1 litre a day or so it would be noticeable by now if it was inside the building. The IR camera would have picked something up too.

Will isolate the boiler and check it separately tomorrow. Going to be a fun day. I don't think the AAVs would cause system pressure to continuously drop - the system would need to be losing so much air it's silly to cause the pressure drops I'm seeing. If it's sucking air in the pressure would increase surely?

Thanks to all for help so far, I'm truly stuck tbh.

 

[Billy Bob Bob]

a failed heat exchanger would cause this kind of drop as would a big leak is there a clear trap on this boiler?

 

[tamz]

I'm truly stuck tbh.

If it is on the system somewhere there is always this
Leak Sealer | Liquids | Central Heating | Sentinel central heating products
It works.

 

[franky]

Here Tamz I was on to Vaillant last month and they said not to put the stuff near a combi as it blocks up the plate to plate heat exchanger don't know if this is true as I've never heard of it.
Heres a number for you I used them once to detect a leak its covered by house insurance but if its not its £750 charge. They drain the system pump it full of some sort of gas and it shows up on there sniffers its a last resort 01480442327 there nation wide I think there called munsters or polygon I'm not sure. Also thats there london price I'm sure there different elsewhere

 

[tamz]

The waterways on giannoni's (hex) are very small and are already prone to blockage but i can't see how a microscopic film would effect them too much Any excuse as usual!

 

[cr0ft]

Thanks for the link Tamz, may yet be useful to me. I've already tried 2x bottles of Fernox Leak Sealer. This worked for a few days and then the leak started again. I'm not too keen to pour any more in to be fair.

I went to the job this afternoon and checked the heat exchanger. It's a clear condensate trap and there are no signs of anything leaking through the trap - even with the pressure up to 2.5 bar. It goes straight out the wall and down to an outside drain anyway though, no sign of it leaking there either.

I've isolated the boiler for 4 hours and we will at least be able to narrow it down to the boiler (don't think it is) or the pipework and go from there.

 

[cr0ft]

Ok, went back and the boiler has lost 0.2 bars of pressure in the 4 hour period. Given that I topped the system up from 1.5 bars to 2.5 bars before I isolated the boiler, could this loss just be down to air in the new water or is it likely to be a leak inside the boiler somewhere? I'm starting to think it's a leak from the central heating pipework to the hot water pipework, could that be possible?

There is no visible leak from the condensate trap or PRV as I said before. There's also no water in the base of the boiler but yet it's loosing pressure.

 

[diamondgas]

Ok, went back and the boiler has lost 0.2 bars of pressure in the 4 hour period. Given that I topped the system up from 1.5 bars to 2.5 bars before I isolated the boiler, could this loss just be down to air in the new water or is it likely to be a leak inside the boiler somewhere? I'm starting to think it's a leak from the central heating pipework to the hot water pipework, could that be possible?

There is no visible leak from the condensate trap or PRV as I said before. There's also no water in the base of the boiler but yet it's loosing pressure.

The only way it'd leak to hot water would be if the pressure C/Heating side was greater than presure cold mains side yeh?

0.2bar with such a small quantity of water could be pretty small!

 

[ratrace]

Here Tamz I was on to Vaillant last month and they said not to put the stuff near a combi as it blocks up the plate to plate heat exchanger don't know if this is true as I've never heard of it.

Bosch said the exact same to me and would instantly invalidate warranty etc. Put me off.