Blocked central heating radiators

[Graeme130650]

Hi,
I have gradually over the years noticed my radiators either going cold all over or going cold at the bottom.I have started taking them off the wall & attempting to clean them out but the water runs clear very quickly and the radiator still feels very heavy when empty.I have also found the supply pipes blocked with a black residue which I have cleared with welding wire & an air compressor!!My question is how do I clear the residue out of the rads.I have filled one with water & blocked the outlets then banged it up & down but it doesn't shift.For info I have put 3 lots of system flush & it still wont flow properly.
Would caustic soda shift it?
My pipes are 10mm micro bores & we have a Vaillent combi boiler.
So there you go.Any advice would be appreciated.
Thanks for reading this cry for help
Graeme

 

[JohnD]

I have put 3 lots of system flush

what chemical have you used so far?

have you been using an inhibitor?

when was the boiler fitted? and the radiators?

how often do you have to bleed the rads?

is it leaking?

did you take the rads off and hose them through?

 

[bengasman]

Chances are your micorobore pipes are blocked. Not an easy job. You probably will need aggressive chemicals to do it which can do more harm than good if you use them the wrong way. I'd get a pro in.

 

[Agile]

Good idea! I always like a pro on the job!

 

[Graeme130650]

Hi John,
I bought the chemicals at Wickes.The boiler was fitted in November 1993.I have taken 1 radiator off & replaced it with a new one (which works).I tried to remove the sludge but it just wont budge.The rads only needed bleeding around twice a year before these problems.I don't have any leaks.I have bought some 10mm pipe & unions to replace the blocked ones downstairs but I don't fancy lifting the upstairs carpets & floor boards or refitting them really.I have bought some Sentinel flusher to have one last go at the easy way.There is no inhibitor in the system at the moment but I have some to put in when I have cleared it.
Thanks for your interest
Graeme
PS I have drained the whole system every time I put in new flush.

 

[YELLERBELLY]

Sounds like the channels in the rads are completely blocked,no amount of chemical is going to shift it.New rads i'm afraid.

 

[bengasman]

This is funny. Out of all the people that responded, the op responds to a householder who has never fitted a boiler properly in his life. Then he gets some wickes crap and wonders why it doesn't work.

 

[Graeme130650]

Hi Ben,
Not sure if you are having a poke at me or not Ben but hey lifes' too short.I have sorted out the problem anyway.The main issue was that the 10mm micro bores were blocked or almost blocked.I lifted the floor boards & cut through the blocked pipes making sure I had isolated the blockage & then put in a length of new 10mm pipe to the main feed pipe,result.All the rads were cleaned & refitted
at the same time.All the rads are now scorchio so I have had to turn the boiler down which is good.So not so daft after all!!!
Best regards
Graeme

 

[Agile]

On a typical pressed steel single panel rad the bottom channel can be cleared by poking it with a rod. But nothing will reach the vertical channels if they are blocked. Hitting with a rubber faced mallet will help but rarely clears a totally blocked channel.

Most pros would use proper branded chemicals and not own brands from places like Wickes!

Tony