i was called to an alpha cb50 today. The pressure had been gradually decreasing and all of a sudden it became faster. I check the prv pipe and it had was not dripping but water was in the pipe and a little wet patch on the floor. So get to the expansion vessel and no charge what so ever. So i pump it to .8bar as I could not find in instructions what pressure to put in it. so i wack heating on it it rises from 1.2bar to 2.5bar. The aav by the pump has all limescale coming down from where it has been leaking. Do you reckon it is too small this vessel and I should tee one into the return?