Central heating pumping over into expansion tank?
Pumping over’ is where water is forced up the ‘open vent’ into the Feed & Expansion tank. Causes can be; – The circulator pump is incorrectly sited – The pump is oversized – There is a restriction in the system The first answer might have the solution, extending the vent pipe can solve this problem if it is due to poor installation design. Also have you had to replace any rads due to corrosion as the if it is due to a blockage this can cause excessive air in the system causing corrosion to of the rads this corrosion can then lead to the blockage becoming worse and so a cycle begins. Any blockage will usually at the point where the cold feed enters back into the system.
