I have a Potterton Promax HE system with 3 rads downstairs and 4 upstairs.
The bathroom and bottom of stairs are the first to get hot when the heating is on.
For a while now I have noticed that there seems to be a lot of air in the system - there is an air/water noise through the pump when it kicks in for a few minutes and the boiler seems a little louder at this first stage too (guess the air going through it's pump).
I have tried bleeding them, and the radiator at the bottom of the stairs always has an amount of air in every couple of days. None of the others have any air in when bled.
There are no obvious leaks in the system and everything is running fine - perfect heat (too hot if anything). One of the upstairs rads is turned off with the rad valve, all other rads are on full.
There have been many problems with the system in the past - 3-port valve heads replaced 3 times, several boiler repairs (nothing to do with water or pump). Also the 3-port valve body was changed recently as it was leaking - the radiator at the bottom of the stairs was removed to drain the system for this.
Like I say though, there are no leaks obvious anywhere and everything seems fine, so can't figure out why there would be air in it.
Could anything in particular be causing it, and what can be done about it?
The bathroom and bottom of stairs are the first to get hot when the heating is on.
For a while now I have noticed that there seems to be a lot of air in the system - there is an air/water noise through the pump when it kicks in for a few minutes and the boiler seems a little louder at this first stage too (guess the air going through it's pump).
I have tried bleeding them, and the radiator at the bottom of the stairs always has an amount of air in every couple of days. None of the others have any air in when bled.
There are no obvious leaks in the system and everything is running fine - perfect heat (too hot if anything). One of the upstairs rads is turned off with the rad valve, all other rads are on full.
There have been many problems with the system in the past - 3-port valve heads replaced 3 times, several boiler repairs (nothing to do with water or pump). Also the 3-port valve body was changed recently as it was leaking - the radiator at the bottom of the stairs was removed to drain the system for this.
Like I say though, there are no leaks obvious anywhere and everything seems fine, so can't figure out why there would be air in it.
Could anything in particular be causing it, and what can be done about it?