Vokera Linea Plus-had issues with DHW for some time (fluctuate hot and cold). Arrived home one day to find water running from the overflow in the attic but don't know if this was related to the boiler. Several weeks later the pressure release valve was opening and I called a plumber who shut this off. Anyway - cut to the chase - boiler will work no problem on heating setting and will supply DHW (still runs hot and cold though) while heating is running. If the heating goes off (ie timer setting) the boiler loses pressure and locks out. Am I looking at more than one problem here or are the syptoms related? Many thnx. Steve

