Air lock in heating circuit?

[Robert Tyrrell]

I swapped out a radiator for a guy last week and now two radiators that are next to each other and running off the same pipework are only getting warm not hot while the radiator on the other side of the room stays stone cold. I've checked the system pressure at the boiler and made sure that it's at least 1 bar, bled the rads several times - nothing.
Anyone got any ideas what could be causing it? It's a combi btw and the system uses 10mm plastic pipe with pushfit joints.

 

[Paulus]

Try turning off all other rads except the ones that aren't getting up to temperature. This usually clears any airlocks.

 

[petertheplumber]

Robert, you didn't say if they were bleeding air out ok. If there is no air in them, it isn't an air lock it just balancing them all. You should know how to do that I would assume.

 

[patrick36]

Hi Rob I have had radiators like that. If you think you have got all the air out then they will work. I have found it can take 2-4 days on some heating systems. I always tell the customer it needs to be on for long periods at a time. If they do not work then and you go back, you can usually find air in system then after it has moved.

 

[Robert Tyrrell]

Try turning off all other rads except the ones that aren't getting up to temperature. This usually clears any airlocks.

Thanks for the advice - I was being a bit of a numpty really as I do know this stuff, just having the Monday morning thing I guess
I actually stuck the hose on the drain off, switched the heating on and then opened up the drain off. Some water came out followed by very loud gurgle noise and the rad started to get hot.

I just have a problem with the one rad that's been 'Linked' into the existing rad pipework via t-joints; it won't get hot, merely warm. Tried balancing the return on the first rad to force the flow through the second rad but it still gets warm rather than hot. Oh well, the guy is happy for now, just annoys me when I can't work out what's wrong.

 

[petertheplumber]

Glad you got it sorted we all have the odd off day were they brain cells don't cooperate. most rad problems seem to be balancing once valve probs have been eliminated.