Guys. Fitted Vitodens 100 six years ago. Last 2 days rads struggling to get hot. Boiler flow temp quickly up to 70 deg from cold and flow immediately off boiler same, but circulation to rads very slow. Am I right in thinking step motor cartridge (div valve) is stuck in mid position. Hot water ok when there is a demand. Removed cartridge today and it was sat midway !
Any help appreciated.
Any help appreciated.
