Unvented cylinder over pressure

[Madrab]

Yep, just had a look at the MI and the expansion relief valve is 8 bar, it's just that's unusually high. The max you usually get on the control set is 6bar.

I would recommend a service of the cylinder, as @muggles comment. It is important that these cylinders are serviced yearly, same time as the boiler would be the ideal.

 

[AndyPRK]

ive Done that procedure thank you.

Took a bit longer than I expected.
5 minutes maybe of draining

 

[AndyPRK]

That procedure doesn’t tell you when to turn the tap off.

 

[JimCrow]

That procedure doesn’t tell you when to turn the tap off.