S Plan Pumps over when hot water valve opens

[joncar7]

I have taken the expansion pipe about a meter above the tank but it still pumps over. Tank does not overflow so I have ruled out a faulty coil in the cylinder.
It does not pump over if just the heating is on but does whenever the hot water valve opens.
This doesn't make sense to me.
Any ideas??

 

[Dan Robinson]

Yes. Your feed and vents are in the wrong place.

 

[joncar7]

Dan can you elaborate a bit please? The 22mm vent is taken off the flow just before the 2 motorised valves. I am not sure where the feed is connected in, where should it be? - Jon

 

[Dan Robinson]

And where is the pump? Just before the vent?

 

[joncar7]

Thanks Dan you are right, the pump is just after the boiler