my vaillant 837e stops heating water and central heating once or twice a day,when it does this fault code f24 displays itself i then press the igniter and everything works fine for a while but later and once again the same f24 fault code comes up.On reading the manual f24 indicates air in the system so i bled it,or air in the pump so switched it to the second speed everything was ok for a while the it reverted back to f24 again.Am i looking at buying a new pump or pump head at least and if so which grundfos do i buy because i can't find any reference to the part number for the pump on the web anywhere.

shaun, March 2008

Turning the pump speed down will not help, did you try bleeding the pump?

Maily the common place to get the air lock is in the heatexchanger, not simple to remove, takes a bit of messing.

Make sure the cap on the auto-bleed vent in the boiler is open (for a while) turn the screw on the front of the pump most way open to get air out of pump (you'll get a little bleed of water there too so have a small towel in place not to get water on any of the electrics in the boiler.

Make sure your system water pressure is correct, bleed all rads and try remove all air anywhere you find.

T, March 2008