Hi
I am sure one of you guys will know the answer to this. I have a relativly new Boiler installed in an old Microbore system. The boiler is oil fired. When the new boiler was installed I had an extension added but the plumber used 15mm traditional plumbing. All was well. Recently I have added several new radiators to the microbore part of the installation (very proud) along with the TRV's. Of course I have drained down and up (twice in fact). Both now and after the previous drain down I am gettting a bubbling noise from the hot water cylinder area towards the radiator in our bedroom every time the system fires up. It is getting worse. I have drained all the radiators and there is never any air. I tried draining the vent next to the hot water cylinder (the pump is in the same location btw) but nothing at all came out (water or air). So now I am stumped.
Any help anyone please
Thanks!
JP
