Ariston Genus 27BFFI leaking

[Boilermania]

My Ariston Genus 27BFFI combi boiler leaks for a while every time after I have taken a shower. If I take the front off it seems that the leak is coming from a very large nut on a pipe coming out near the top of a large cylindrical vessel on the right hand side of the boiler. I have tried unsuccesfully to tighten the nut as it is extremely inaccesible and very large.

I have had one plumber round who reckoned he had fixed it, but he hadn`t - the leak returns every time I take a shower. The central heating works fine and doesn`t affect the leak.

Can anyone PLEASE help

 

[Simmo1]

Tightening the nut will not help if a washer has perished or is damaged. I would guess from your description that the boiler leaks whenever you demand hot water from any source for a significant period - not just the shower.
Get a bona fide boiler engineer to identify the exact location of the leak as water will run and may not be coming from where you initially think. Wherever its coming from will require draining the boiler to remove the part and replace the part/washer(s). Your description sounds like the expansion vessel but it's possible there is a leak somewhere on the DHW circuit. It's hard to say without seeing it. This work can be quite tricky and will require a certain level of expertise.

 

[ChrisR]

Sounds like the automatic air vent to me. Try doing up the small black plastic valve cap. But it needs replacing.

Went to one of these recently with parts to repair 3 leaks I'd seen earlier, but on closer inspection (having taken the pressure up to 2.5 bar) I found another 4 leaks, so went home again. It'll turn into a 2-3 hour job I expect.
Mostly from the connection valves but also the DV and block on the right. ..

 

[DP]

Chris I think the man is refering to the top cylinder union.

It can be done, but the insulation is in the way.

Also, check the white vessel is intact. Boiler design kills this vessel.