Kettling Ideal Classic RS80

13 Nov 2004
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United Kingdom
My boiler is kettling, worse during warm-up than when up to temp. I cleaned the system with Sentinal X400 last year. The kettling died away after about 10 days. I flushed the system out afterwards, added X100, but the kettling started again almost immediately! Checked today and I have black sludge in the boiler.
I have another bottle of X400.
Can I add this to the system whilst the X100 is still in there or do I have to flush with water first?
Can I leave the X400 in for longer than 4 weeks to give the system a thorough clean?
Is the Sentinal stuff any good or is Fernox DS-40 better?
Mark. :(
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Perhaps better to try to work out why your system is creating more corrosion products...

Although inhibitors do suppress oxidation, they cannot stop it altogether. Is your system getting air inot it somewhere: eg. pumping-over into F&E tank? microleaks on the suction side of the pump? are you sure that what you identify as 'kettling' really is, and not air passing through the pump and boiler?
Definitely kettling and not air. Does it with bypass wide open or closed. No overflow into tank. Pump is on outlet of the boiler.
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Thoroughly flush crap out of system, rectify why system is sludging up, Put in X200 and X100 and leave it in.
The system is 8 years old. I gave the system a good flushing through 2 weeks ago with boiler off, pump on full, constant drain from the bottom of the boiler for 2 hours in an attempt to flush the crap out. I assume the crap is baked onto the inside of the boiler.
Last year X200 didn't cure it after 6 weeks, X400 silenced it after 10 days so I'm pretty sure it's due to scale from corrosion deposits rather than limescale.
I believe X400 will cure it again, but should I leave it in for the full 4 weeks (or longer) to ensure all the scale has dissolved?
Is X100 as good as Fernox inhibiter?
Will Fernox inhibiter + boiler silencer give better corrosion protection and stop further scale forming in the boiler?
kettling = limescale mainly heat exchanger, virtually impossible to remove.
Reddish water and sludge problems = Air in system, fix leak / poor pipework config., flush and inhibit
Black water and sludge problem = electrlytic corrosion from badly flushed new system, age, poor water quality, no inhibitor. Normally find the air is actually hydrogen, stick a glass over when you bleed it and then light it, if it pops it's hydrogen. Flush and inhibit.
If you want a fighting chance with the sludge you really need a powerflush.
Doesn't cover every case but a general rule.
Will DS-40 make a better job of removing scale than X400?
Will my 8 year old system survive it?

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