Sludge!

[Cold Scott]

My radiators have cold patches in them (bottom and centre is a couple) and one does not work atall. I think it could be sludge - what is the best way to get rid of it - I tried leaving the system flushing (drainin with a house and filling at the same time)...Help winter is approaching

 

[simond]

You have two alternatives:

1. Take off every radiator individually and carefully - then take outside and hose out vigorously.
2. Get the system Powerflushed.

Option 1 reminds me of the famous song;

Take me home, where the buffalo roam
And I will show you a house with a very messy carpet.

 

[ChrisRoberts]

Poweflush.
Taking rads off is so last century.
Plus doesn't clean pipework or debris in boiler.

 

[ChrisR]

Cheaper option works pretty well, but a hose doesn't clear the vertical channels in the rad. If you take rad outside and 1/3rd to 1/2 fill it with water, and invert it a few times (hands over the holes), empty and repeat, turning over the other way if it's a double, until the water comes out clear, you will clear your cold spots.

 

[Nige F]

cold sores are more difficult