Pre Winter Test - luke warm downstairs Radiators

[mike2016]

Hi,

I just finished a test of the heating system as the Radiators have been off all Summer. I'm trying to get to the bottom of why some downstairs rads don't heat up properly. Not a new issue but it's just niggling me currently. There are two larger rads with old TRVs and two other rads without. None of these heat too well. Upstairs is fine.

I took my Flir camera out and had a look. I can see 57 degrees at the inlet of each but it doesn't appear to be heating up the rad as much as it should. The first rad pics below downstairs1 has no TRV, valve fully open, the others two downstairs2 & downstairs3 are the larger rads with TRV's.  I've bled all the rads, no better. Is it sludge or something? 

Thanks! 

 

 

 

 

 

 

Edited August 27, 2018 by mike2016
Annotated Pictures