to cut a long story short my radiators came on when the hot water should of come on. i think the problem is the diverter valve as it seems to be stuck in one position . I tried to push it the other way but it seems to be stuck. do i have to buy the complete unit or can i replace the mechansim on top of the valve itself? if i have to replace the whole unit do i drain the whole system rads and storage cylinder?
Cheers in advance