Could the radiator still need bleeding?

[madammim]

Hi, ongoing heating issues although getting better!

All rads are now getting piping hot except one - its the one we have always had issues with before but eventually after lots of bleeding it usually heats up and is then fine.

We have taken pints and pints of water from the radiator over several evenings but can still hear a hissing noise although water is coming out well. When we do bleed it, eventually it does get hotter. But when the system switches off and comes on again next day, its only luke warm again.

Could this still be an air issue, despite the many many hours bleeding the damn thing?!

Any advice much appreciated.

Thanks, in advance.

 

[Burnerman]

If the system has had new water introduced to it, it does take a while for the oxygen in that water to dissipate.....however, if your system is dirty, the rust inside produces its own gas - hydrogen.
How long has this been going on, and is the water you bleed out black? Only bleed the air away, nothing more.
John

 

[madammim]

Hi John, thanks for replying. It is fairly clear water that is coming out of the radiator - there is a hissing noise in the background when water is coming out of the rad. We have to keep topping up system when excessively bleeding so yes new water is being introduced. It's just this one rad that is barely warm - although it does warm up more if I bleed a half pint or so of water from it!

 

[Madrab]

Sounds like a blockage in the return from that rad. Bleeding the water out is letting the hot water from the flow fill the rad instead of it circulating through the return?