I have a customer who is a bit of a pain to say the least, his most recent complaint was that the new timer I fitted is losing 2 minutes of time over a month (the clock is a little bit slow). Basically I fitted a new boiler for him a few months ago, and there seems to be quite a bit of air collecting in the bathroom radiatior and it needs bleeding on a weekly basis. It has a combined feed and vent, I have never seen problems with this set up pulling in air. I added double the amount of inhibitors required for the size of system aswell. I am struggling to work out where the air is coming from.