i found that with mine , if you over fill the pressure tank you will see the indicator flashing 3.2, 3.3 3.4 and so on when in heating mode, and an hour after cooling down ,all your pressure is gone, try to re fill just above the minimum mark when cold, as the pressure rises during opperating times, the level should be between 0.2 - 3.0 bar , anything above this will result in you constantly topping up and looking for leaks,
pete starks, September 2015