Hi. The pressure has but up on my boiler, now in the red. I have had to bleed a radiator to drop the pressure. There is no air in the highest rad. This only happens when the heating comes on. It looks like the system if filling up when the heating switches on!
It's a valiant ecotec. Only three years old!!

Michael, January 2011

can only be one thing expansion vessel either low on pressure or bag has gone

swifty, January 2011