A friend has a Vokera Linea, When he puts hot water tap on, gets some hot water for a few seconds then runs cold. The temp window on front of boiler starts fluctuating different temp settings then goes to a flashing 07. After a time it comes back on but if you use the hot water it does the same thing again. He tells me he has had to turn the reset button on the odd occaision. He has noticed a bubbling sound in the rads now and again and also a slight loss of pressure which he says he has to top up every few weeks. The Floor is yours guys, tell me your thoughts.