Radiator sludge

[MontyMonty]

Good afternoon,

I have a bay window curved radiator. Last winter the bottom third stopped getting hot. I have presumed this is due to a build up of sludge.

I took the radiator off the wall and flushed it through in the garden with a standard hose. A bit of sludge came out but not much. The water running through it came out clear. I sanded it ready for repainting. After putting the hose back on for a final check a lot more sludge has started to come out. I presume the sanding has dislodged it.

So my question is what can I put in the radiator to help dislodge the sludge? Do I have to use some type of fernox type product or can I put something else in (white vinegar, or citric acid etc). I have already biven it a tap with a rubber mallet. Any advice would be welcome.

For info, I do have a magnaclean filter fitted. And I will be topping up the inhibitor when the radiator goes back on.

Thanks

 

[cross thread]

Carry on with the mallet and hose pipe.

 

[MontyMonty]

Thank you. I appreciate your help with this.

I'm still tapping away and more black stuff is coming out. Will keep at it for a while longer.

A supplementary question if I may. Is it best to put in the same inhibitor as I used before. Or does it not matter. I can't remember which one I used last time.

Thanks.

 

[Jackrae]

Clearly your inhibitor was either put in long after your system had started to corrode and sludge up or it was put in at far too low a concentration.
I'd suggest you refit the radiator and dose your system with a sludge cleaner at the correct concentration. Following the appropriate period of hot circulation (it could be several days) and confirmation that all radiators are getting warm over their whole surface, completely drain the system and flush through to remove all sludge. You may have to 'force' the water to take specific routes by sequentially closing off radiators. Once fully flushed clean, refill with water inhibited at the correct dose rate. However, if your system is badly corroded, the cleaning operation may literally be opening a can of worms.

 

[MontyMonty]

Thank you Jackrae. You are indeed correct. It is a very old radiator (40 years plus). It has not been replaced because of the hassle and cost of acquiring a new curved radiator. All the other radiators are much newer and all work well. The magnaclean has been in for about six years.

I have been tapping away with a mallet and the number of black bits seem to be reducing. I will refit it and then see what happens. I will then consider using a sludge cleaner. But presumably if the curved radiator is working normally then it will be best to leave it.

Grateful if someone can advise on the inhibitor.

 

[Madrab]

if you can remove the blanks at the top then have it on end and flush for alternative hole, turn it the other way, do it again, upside down, do it again, keep re-orientating it banging it all the time, fill it then let it drain, repeat until it run clear.

 

[MontyMonty]

Thank you Madrab. Unfortunately don't have any blanks at the top. But I have been turning it upside down etc. I've also kept my thumb over one end as it fills up. Don't know if it helps but it's quite good fun! You can feel the pressure build up and it's surprising how far the water blasts out once you take your thumb away.

Got to the stage now where the water coming out is clear, apart from the occasional smallish black bit. I assume once I reconnect the radiator bits like this will get caught by the magnaclean, and not cause any problems. I will clean oug the magnaclean before it goes back on and put in a bottle of xentinel x100 inhibitor.

I am annoyed with myself for not doing this at the end of winter and not close to the start. We live and learn.

Thank you all once again for your comments.