Running pipes above boiler - air trap?

[Ehy352]

Hi

We installed a combi boiler in an upper flat by taking the pipes up (above the boiler) and into the loft, and then dropped them back down to the radiators in 3 different rooms (as opposed to the normal method of running the pipes under the floor beneath the boiler which was not possible in this flat).

We now started having F75 fault problems which we think could be caused because of air trapped in the loft pipes. Our thinking is that since there are no radiators above the boiler (in the loft), it is impossible to get rid of any air that rises above the boiler, and gets trapped in the loft pipes above the boiler.

What do you think? does the automatic air vent in the boiler get rid of the air trapped in the pipes above it, or do we have to go up into the loft, and install an automatic air vent there at the highest point to get rid of any air that might get trapped in these loft pipes?

Thanks

 

[Gasmk1]

Yes you need vents in the loft or fit an air separator

 

[Ehy352]

Yes you need vents in the loft or fit an air separator

Thanks for getting back to me. Can we just install two automatic air vents in the loft pipes at the highest points, one on the flow, and one on the return? I assume if we just put one on the flow, it will not get rid of air in the return because it is a separate high point loop, is that correct?

 

[Scott_D]

Yes you need to vent the flow and return.
It could be a manual vent or you could try blasting water through from the filling loop and out of a drain off first

 

[Ehy352]

Yes you need to vent the flow and return.
It could be a manual vent or you could try blasting water through from the filling loop and out of a drain off first

Thanks, we installed a an automatic air vent on the flow and return, and it works now. We were worried however about the pump sucking in air from the return automatic air vent, so once the system was free from air, we shut off the automatic air vents. We can reopen them in the future if needed