Air in rads - is it due to pump?

[coombsie11]

Have an open F&E system.

Had a few problems recently with the central heating. - Primarily clanging, whooshing noises.

Thought it was due to the pump - so I replaced the pump.

Next pilot on boiler starting going out - So got someone in who replaced the Thermo-couple, as system was overheating.

This resolved banging and pilot issues, but now get alot of air in rads.

Have turned off pump - bled all rads, bled HW cylinder, bled pump. But air is still an issue. Bleed every other day.

I noticed that the pump is on all of time - even when the heating is off. Is this right? or should it only kick in with the program/timer? Could this be causing my air problem.

PS: when rads are bled they work fine (heatwise)

Thanks for shedding any...

 

[GasAid]

Has the pump been installed the right way round?

Do you bleed with the pump on or off (You should only bleed with the pump off)...?

What setting is the pump's speed currently on and what happens when you reduce the speed; putting a pump that has a 1-3 speed option on 3 will not necessarily mean you get a faster heating house. The speed needs to be set to the size of the system.

What boiler is this on? The pump running all the time could be due to a pump over-run stat or timer that's gone wonky and needs replacing.

Is the header tank full with water and is the open vent pipe constantly rising; except where it diverts into the header tank; and is the clearance between the header tank water level and the tip of the open vent over a 10" distance?