Plumbing problems - header tank warm

[hillheadRod]

Hi,

I tried turning my central heating pump from speed 1 to 2 to make the radiators warm up faster. In about 2 days the system was full of air and gurgling terribly. On investigation the header tank water was very warm. I noticed that the expansion pipe outlet was below the water level. It is a vented system so I expected there to be an air gap. Can anyone tell me whether this would explain the air getting into the system and whether it is important to have an air gap between the expansion pipe end and the header tank water level?
Many thanks,
Rod

 

[John506]

Yes you need an air gap, and it should be higher then the overflow pipe inlet.

 

[bengasman]

5 gets you 10 the system is full of carp