Dont know if anyone can help but i have a weird issue with my Vokera 80SP boiler. whenever the heating starts up from cold the pressure goes wild for 3 or 4 seconds then settles down. this doesnt happen when running water or after the boiler has been on while, knocks off with the room stat and then starts up again. It only happens when the boiler starts up from cold or has been off for a while. Anyone got any ideas?? its not a problem at the moment but obviously i dont want it to get any worse and be left with no heating, especially as it gone so cold over the last few days