Sd30e pressure rising and falling. Still got problems .

[picasso]

All you need to do is make sure the boiler has no water in it as you repressurise the ev so that your not trying to pressurise the whole system, leave the drain cock open until the water stops then pressurise the ev (leave the drain open all the time)until your ready to refill the boiler.

 

[jimbobaroo2]

All you need to do is make sure the boiler has no water in it as you repressurise the ev so that your not trying to pressurise the whole system, leave the drain cock open until the water stops then pressurise the ev (leave the drain open all the time)until your ready to refill the boiler.

Thanks picasso.
Will try again later and let you know.

 

[boulevardier]

I may be stating the bleedin' obvious, but have you checked that the radiators are all properly bled? I had similar problems with boiler pressure all over the shop, which baffled me and a British Gas engineer - until it occurred to us to check that. When you're deeply immersed in technicalities of boiler pressure shooting up and down, release valves operating, etc, it's easy to forget something simple. My problem started with a leaking expansion vessel, but the bizarre pressure problems came afterwards. If there is air in the system, it will expand at a much greater rate than the water when heated up, so it fires the pressure relief valves, and so much water is ejected that the boiler looks (and is) unpressurised when it cools down again. So, it then looks as though fixing the expansion vessel hasn't cured anything. Sorry if I'm insulting your intelligence, but it did happen to me (and to that BG engineer!).