oh my God
I followed your instructions! I turned on the boiler at the electric switch (mayb I shouldnt have done this bit??)the light came on, I found the valve you said and I turned it on, I heard the gushing noise and I turned off the valve when the needle got to 1. Panicked when the needle continued to rise to well over 3.5! switched off the boiler, I had visions of the house blowing up!! screamed for my husband!! then When i thought the needle would go over four there was this almighty hissing noise and water started spitting out at the bottom of the boiler and at the vent outside the house!!
We called an emergency number who reassured us the boiler wasnt going to blow up( at this stage I was going to start evacuating the neighbours)
he said the water was being released to reduce the pressure and said it prob would do this for an hour or so. He said the water should not be coming from inside the boiler so its very possible we have a leak which is why its stopped working and why the pressure was getting low. (our boiler is tucked away in a cubboard in the utility and I havnt noticed any water there before, there could be some (there is plenty now!!) We are going to get someone out tomorrow!!It is still releasing water even now!!