SLUDGE!! ....................

[suzyd]

Sludge ... what exactly is it and how and why does it enter a central htg system?

How do you def. know your system has it?

Is sludge remover x400 any good?

any good tips to remove it from your system and to keep it out?

 

[JohnD]

(1) it is mostly the products of corrosion, where your steel radiators are "rusting" away (it is not exactly brown rust, unless you have a lot of air in the system, but that will do). It is mostly black iron oxide. Because you have at least two metals in your system (usually copper pipes and iron in the steel radiators) you will get corrosion even if it does not contain air.

(2) A system which is old, or vented (has a feed and expansion tank in the loft), or neglected (has not been kept well-inhibited) will usually have sediment in it.The more of these conditions apply, the worse it will be. Eventually it causes blockages.

You will find you need to vent the radiators because the corrosion releases gas. You may find the water is visibly black. If you take a radiator off for decorating you may find black sludge comes out of it.


(3) yes. Bale out all the mud from the F&E and sponge it clean before you start, and if the system is obviously very dirty, drain it out and give it a fresh-water flush and rinse just to get the loosest stuff out. Draining is more effective if you fit a full-bore 22mm hose valve on a convenient pipe, the water gushes out faster so carries more muck in it. If you put the valve on the Return side of the boiler it will not get so hot and will last longer.

If you have actually got a blockage that no water circulates through, X400 will not remove it as it cannot flow through the blockage,so the pipe will probably have to be cut out to remove the blocked part.

A Powerflush is more effective, but costs hundreds of pounds,while you can do a chemical clean fir £15 plus a few hours of your time.

(4) make sure that air is not getting into the water, e.g. by pumping over or suction side of pump leaking,or a water leak which is constantly being topped up by fresh water
Then, after you have given it a good clean, refill with a good Chemical Inhibitor such as Sentinel X100.If you can do basic plumbing and afford £100, fit a Magnaclean too. It will capture circulating black particles before they are able to accumulate into sludge or hard sediment,and I promise you will be amazed and delighted at how much it traps.

Fernox is another top brand

I am just a householder

 

[Fluffster]

Sludge or Magnetite is created when water, heat ,oxygen and metal mix.
Basically it is liquid rust.
You can tell by draining off and if you see black water or treacle type substance you have it.
Also causes cold spots in rads as it gathers in the middle and the water has to flow over the mound of sludge.

You may need a powerflush depending on the severity of sludge/magnetite you have.

Also a magnet that sticks to copper pipework induactes the presence of magnetite.

Pete

 

[suzyd]

Thanks for your replies so quickly as well. One further question I have is why does pumping over draw air into the system?On top of this after opening the radiator air vents, the upstairs radiators have black liquid escaping but the downstairs ones are clean? How comes? It is strange?!

 

[JohnD]

the water is flowing out of the pipe, passing through the air, and splashing into the tank. While doing this it picks up air bubbles, and absorbs and dissolves air.

Like if you squirt the cold tap into a glass, you will see it contains bubbles.

see 47
//www.diynot.com/forums/viewtopic.php?t=37170&start=0

and others for background

 

[suzyd]

Thanks John again - i feel so silly now asking that question! Lucikly my pump is fine and not pumping over and the system layout seems to be good as it has been fine for the 12 years I have lived at this house!

 

[suzyd]

I am puzzled as to why my upstairs radiators have black water escaping (seems thicker than nomal water, but only a little) and my downstairs radiators are clear when vented! Is this normal?

 

[JohnD]

it might be that your upstairs rads have a faster water flow and it stirs up the sediment? Or maybe they have more air in them? Or maybe they have not been vented much and some material is clinging to the vent pin? Dunno.

 

[suzyd]

ok fair enough.

if i add sludge remover for a week and then some new corrosion inhibitor will this prevent any sludge from enetering the radiators and the system again?

 

[Bahco]

John

A lot of your content on Sludge would make a good FAQ if you have the time.

 

[Onetap]

(1) Because you have at least two metals in your system (usually copper pipes and iron in the steel radiators) you will get corrosion even if it does not contain air.

Not so. Bi-metallic corrosion also requires a suitable electrolyte. The inhibitors make the water alkaline and stop it acting as an electrolyte.

You will find you need to vent the radiators because the corrosion releases gas. .

If it is bi-metallic corrosion, you get hydrogen released at the rad air vents. The electrolysis breaks the water down into oxygen and hydrogen; the oxygen reacts with the steel to produce the black sludge. The hydrogen accumulates at the air-vents or high points.

A power flush probably won't remove all the sludge from a system, even the few that are done properly.

 

[jackecole]

Although soft water (acidic) can be the electroltye, fresh air and water together can also make 2 metals slowly corrode.

The steel rads slowly rust, the rusted metal falls away and the fresh metal underneath is then rusted away further ... leading to problems down the line.

 

[Onetap]

Although soft water (acidic) can be the electroltye, fresh air and water together can also make 2 metals slowly corrode
(ie the steel rads slowly rust, the rusted metal falls away and the fresh metal underneath is then rusted away further ... leading to problems down the line.

It corrodes due to dissolved oxygen, either absorbed from the atmosphere or produced by electrolysis due to bi-metallic/galvanic corrosion.

The galvanic corrosion cell needs 2 dissimilar metals and a suitable electrolyte.

Soft water is usually neutral. Softened water is very slightly alkaline, I believe.