Air locks and water coming from overflow

[dmcglone1983]

Hi, I have in my house two heating systems, one is oil-fired central heating, the other is a back boiler. I've started to notice water coming from the over flow from the small tank up high in the roofspace. (When the oil heating is on) The hot water taps are forever air locking. I have to run the hot taps for a while to clear them, otherwise the water is just dribbling from them. Would anyone know anything about this. (Ps I've no plumbing experience)

 

[GArlington]

It is near impossible to advise on this without knowing the complete setup.
Did someone accidentally plumbed hot water overflow into heating header tank (small) instead of cold water header tank (large)?
Check that the filling float in heating header tank is set correctly, i.e. low enough to provide enough room for water expansion. Check that the header tank itself is big enough.
Your hot water problem may be or not be related to the dripping tank...

 

[Bunker]

Does it happen only when oil heating on or also when hot water on only? (Unless gravity of course). Gents, could this possibly be the infamous 'holey coil'?