Biasi Riva HE. They built a boiler you cant service.

[Nostrum]

Doh, i'm confused, you are right !

 

[Armitage Shanks]

I tried all AF sizes, whitworth etc. None fit. But your all missing the point. Biasi tech told me " even if a spanner fitted ,it wont undo it because the thread is too large for the torque you can apply through the small brass nut,it just shears ". The nut is part of the casting.
When you see it youll know what I mean.

 

[southcoastboile]

I diagnosed the problem in 2 mins, magnetic proximity switch not energised for DHW. Ok, lets clean the flow switch. Errrrrrrrrrrr, none of my 65 spanners or sockets fit the top nut, to big for 17mm, too small for 18mm. Out of curiosity I call tech, they say" oh ye, its a problem, throw the whole hydralic block away and fit a new one". The DHW gauze filter is in there and should be cleaned as part of a service.
I did actually manage to remove the plunger assembly in the end after much cussing and removing other components to give more space for a pair of stilsons. Whilst I had the part out I also filed the brass nut to fit a 17mm ring spanner, so in future it will be easy to service the filter and plunger.
Well done Biasi, I wont be recomending any of your products any time soon.
Any other engineers had the misfortune to come across this one?

Wait till you try and change a pcb on one! its unbelievable how bad it is to do, thank god for thier technical line.