Faulty water cylinder thermostat?

[Harry Bloomfield]

It’s me the OP I set the boiler to 70 and the hot water cylinder only clicks at around 35 it never clicks at 60

Thanks, but I already knew that and there is an issue with your system. Under 'discussion' is a fully working system - my apologies for your thread being kidnapped!

 

[Hugh Jaleak]

First thing I would be doing is to open the air vent cap on the Primary return on the cylinder, and try to vent the cylinder coil. Given the fact you are saying those pipes are only warm, would suggest there may be an air lock in there, or some other obstruction impeding circulation. The 2 pipes you have indicated as 'Warm' should be red hot if the boiler is circulating correctly, these are feeding the coil inside the cylinder, which in turn heats the hot water.

If that doesn't achieve the desired effect, then I would suggest fitting another air vent cap to the 22m stub on the Primary flow, where the former vent has been capped. Why on earth this wasn't fitted with a vent cap at the time I do not know.