Yeah, it drops when the heating is off, and goes up again when it's on.
When the heating is off the gauge is right down at virtually nothing - I fill it about once a week to get the pressure up to about 2 bars when the heating is on.
Question: should the gauge be showing running pressure or 'boiler off' pressure? I.e - should I charge the boiler up so that it shows 2 bars when it's not running?
A few months ago there were some drips coming from the actual boiler but that has stopped since so this doesn't seem to be the problem.
I'm pretty sure the the rads were installed with the boiler about 15 years ago.
Black 330d E90 LCI M Sport Saloon Auto. Privacy Glass, Cream Leather, 6FL, I-Drive/Nav/Bluetooth, Alpine hifi upgrade.