Possible sludge in radiator

[chiller15]

The radiator in my living room has been faulty since I bought the property two years ago. It's warm-hot at the top and cold at the bottom, which is the opposite of the common 'it needs bleeding' issue. I have bled it anyway, just to be sure. I'm suspecting that it has 'sludge', a build up of gunk at the bottom of the radiator.

This is the last radiator in the system and the feed pipe to it is scolding hot, however the return pipe is luke warm at best. All other radiators are working perfectly. The common fix for sludge in a radiator is to remove it and blast it out with a power washer or clean/flush the entire system. Both of which appear to be more expensive than just replacing the radiator

My question is; Do you think replacing the radiator would fix the issue? I wouldn't be doing this myself, I'd be getting someone in to do it. I don't really want to spend the money, only for it not to fix it.

 

[Gasguru]

Unlikely to be sludge it's very rare. More likely just a straightforward balancing issue.

 

[chiller15]

Hm, cheers for that. Would flushing the system sort something like that?

 

[Gasguru]

No...balancing is all about getting a sufficient flow to each radiator to ensure the temperature drop across each rad is similar.
It is done by opening up all the thermostatic valves (or manual wheelhead valves) and adjusting the lockshield valves as appropriate.
Read the FAQs.

 

[CBW]

Unlikely to be sludge it's very rare.

Why is it rare? I thought it was still common?

 

[Gasguru]

Claiming sludge in a customers radiator and quoting for powerflushing is the biggest racket going on in the heating industry (in fact powerflushing could do more harm than good).

That is the sole reason why the public have a perception that cool radiators must be sludged up.

Genuine sludge can only be deduced if the rad flow and return pipework temperatures were within say 20 degrees AND the lower middle section of radiator was significantly cooler after some time to stabalise.

The vast majority of so called sludge issues on here is due to poor balancing...evident by a large difference in flow and return temperatures.

Of course you can get a slight buildup of debris across the rad valve seatings especially if the lockshield's only open say an 1/8 turn or a TRV with very small ports (Danfoss) but that is not the same as sludge.

 

[chiller15]

Genuine sludge can only be deduced if the rad flow and return pipework temperatures were within say 20 degrees AND the lower middle section of radiator was significantly cooler after some time to stabalise.

That does sound like my situation though, there is a massive temperature difference between the hot top and cold bottom, as well as the feed pipe it almost too hot to touch and the return pipe is luke warm at best.

 

[CBW]

That does sound like my situation though, there is a massive temperature difference between the hot top and cold bottom, as well as the feed pipe it almost too hot to touch and the return pipe is luke warm at best.

I would try balancing it first though.

 

[durhamplumber]

Unlikely to be sludge it's very rare. More likely just a straightforward balancing issue.

Agreed...Found loads of sludge once or twice in 15years of domestic heating.

 

[dilalio]

Even if it is sludge, simplest approach for the OP is to first shut all other rads and focus flow on this problem rad... This can get the waterways flowing through the rad and disperse any build up that may go back in to suspension and be distributed around the system.
Or just take the thing off and run a hose through it in the garden... Simple job if you're physically able.