central heating boiler leacking from relieve valve

ladybreaker

Help please.
I have a Alpha SY24 wich was leacking from the relieve valve.
But every time I was filling the system at cold to 1bar, as soon the water was getting hot the pressure build up to 2.5bar
At some stages the system was loosing its pressure from the relieve valve to 0bar, so I thought to replace the releieve valve to solve the problem.
But it keeps doing the same thing with the new valve.
Is the expantion vessel the problem.
Please advise.

Tom Struble

is it possible the fill valve is not shutting all the way?

metx

check the expansion tank ,if all hot then water log .pressure in tank should be 12psi .drain the tank. that should do it

ladybreaker

The filling loop is removed every time I fill the system.
I will chek the expantion vessel pressure
Thanks to all