hi has anyone had this problem before or any ideas what it could be its a glowworm swiftflow 125 electronic and basicaly when heating is off hot water works fine but when heating is on and you turn the hot tap on the water is red hot about 65c (has scalded someone) then it cools of to normal i know on these boilers there no plate heat exchanger and it runs through the normal heat exchanger but the customer has only just started getting this problem ive checked burner pressure flow rate checked the themisters checked all filters these are all fine spoke to glowworm tech and they have no ideas