Sludge In Radiators

[dinger71uk]

sorry for reposting this

I moved into the house in august and the system is a ariston a27 combi, shortly after moving in noticed the bottom half of three of the radiators were cold but top half boiling hot. I also had the filling loop and a gasket replaced as water was leaking very slightly needing the pressure to be topped every week or so, meaning there was prob no inhibitor in the system and by all accounts the guy before was a bit of a miser.

1.) Got a powerflush done using x800 by local plumber still not warming up and not much sludge removed.
2.) Asked him to remove one of the troubled radiator to see if there was any black sludge in system.
3.) Found sludge in radiator so took hose pipe and large mallet and hit radiator for several minutes until water ran clear.
4.) repated three other rads that seemed to be a problem
5.) hesating back on and have spent a few weeks trying to balance the system but three rads down stairs still cool on the bottom.

Another gas engineer has suggested replacing them. Any thoughts from the experts.

Cheers

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[Boilerman2]

New radiators would not be overly expensive so probalby worth changing them fit a magnetic system filter on the heating return as well

was your flush a "Powerflush" or just a "soft" flush using X800?? I would have thought a properly excecuted Powerflush would have removed most of the system debris! - "soft" flushing is not always effective

 

[dcawkwell]

Close the radiator valves on all the radiators except one of the problem radiators. Open the valves on the problem radiator fully.

Switch on and see what happens.

A few hours of the central heating pump pounding water through it might sort it.

 

[dinger71uk]

just closed off all rads apaprt from on of the problem ones see how that goes for an hour or so

 

[dinger71uk]

one radiators is very toasty at the mo, ill see what its like now all the others have been put back on

 

[jackthom]

Top of radiator hot and bottom cold isn't always due to sludge in the radiator.

After running heating for a while check that both pipes connected to the radiator are hot. If one is cold it's a flow problem, possibly sludge in the pipework or system in need of balancing.

 

[dormermike]

I've recently found that the bottom of the rad being cold was actually due to air - probably in or near the return pipe. The only way I could shift it was by taking a few litres out of the drain valve from the rad, and it coughed and spluttered as air came out and yet no air was produced at the bleed screw.

 

[dinger71uk]

there are five rads that come off the same pipework and two are ok, the other three are the problem ones. Im now wondering if there is a blockage, although when i turned off all the rads apart from one of the troblesome ones it did get very hot usually the lockshield end is fairly cool.

 

[dcawkwell]

there are five rads that come off the same pipework and two are ok, the other three are the problem ones. Im now wondering if there is a blockage, although when i turned off all the rads apart from one of the troblesome ones it did get very hot usually the lockshield end is fairly cool.

What is the size of the pipework feeding the 5 radiators.
If only 15 mm it isn't up to the job.

 

[jackthom]

if you can get a good flow through each radiator while the others are off that's a promising start.

It's possible the system only needs balancing now but if that proves very difficult there are cleaning additives which might help flush out any remaining gunge in the pipes.

As dcawkwell says the design of the system could be at fault.

 

[dinger71uk]

from memory its 22mm then 15mm branches off it to the rads, will need to lift a few floorboards to see.

 

[dinger71uk]

two of the five tee off a 22mm pipe the 22mm pipe then disappeas out of sight until i can lift the foorboards. the other three are a good size 1600*700 double panel a 1400*700 single and a double 1000*700.