Heating works but no hot water: any suggestions?

[Sarrusophone]

Have you found information/image online? I’ve just found some, that appear to have a gap between head and valve, which suggests, it can be removed?

From what I can see, it is held in place primarily by the valve itself. I think it might just be a c-ring that’s keeping me from removing it but it is quite hard to investigate since, inevitably, it has been installed facing away from the cupboard door and there endless pipes in the way...