# Radiator question



## nutts (May 8, 2002)

Some of my radiators are cold in the middle / bottom (see pictorial representation)...

Tried bleeding them, but there is no airlock in any of the effected radiators...

Any ideas?


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## coupe-sport (May 7, 2002)

Limescale build up in the centre ? - just seems somewhere where limescale will drop out of the flow and build up.

James


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## l3ett (May 6, 2002)

Dirt/Sludge in the bottom?

Have you removed any recently? Could have had some crap come in via the cold feed i guess??


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## aidb (Mar 19, 2003)

I found this Mark:

http://www.diynot.com/pages/pl/pl033.php


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## garvin (May 7, 2002)

Sounds very much like the radiators are 'sludging' up - a good indication of this (but not foolproof) is if the water that comes out of the bleed valve is heavily discoloured.

You can purchase a de-sludging additive from most well known DIY outlets which you put in the heating system header tank and bleed it down into the system by partial draining. It is left in the system for a few days during which the system needs to be running/heating before the whole system needs to be drained. Finally the system needs to be refilled with the correct amount of corrosion inhibitor.

Some times this is not successful and the offending radiators need to be physically removed and flushed through manually with a hose-pipe.

Alternatively, a heating engineer (that's a plumber by the way ;D) can flush the system through using a reversing pump. They connect this into the system via flexible pipes and then turn all the raidiators off bar one and then flush thorough one way until the water runs 'clear' and then they reverse and flush through the other way until it runs clear again. This flushes one radiator, its associated pipework and the boiler. Each radiator gets the treatment 'in turn' (the boiler gets a good 'going over' as it is flushed each and every time). Finally when all radiators have run clear the system is drained and refilled with fresh water with the correct corrosion inhibitor.

I live in a very hard water area and have this done every seven to ten years. It's not cheap but it keeps the heating system and boiler in tip-top shape.


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## Chip_iTT (Nov 14, 2003)

Yes, had this same problem in the upstairs rads recently after putting new rads in the living/dining rooms. Basically were all sludged up... used the desludging stuff...worked a treat...but beware... if there is any pinhole corrosion blocked by the sludge..... the rads were installed in 1977 and the bathroom one sprung 2 leak in the bottom seam after desludging!


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## nutts (May 8, 2002)

Well the general consensus is sludge then :-/

The radiators are only 8 years old, but I'm guessing that enough sludge can build up over this time...

Registered on the above forum (diynot) and received a suggestion to turn both valves off, remove each radiator and flush them with a hosepipe... :-/

Will probably go for a de-sludge additive and then flush.

I suspected that this maybe the problem and solution... just didn't fancy it ;D ;D

Cheers guys!


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## t7 (Nov 2, 2002)

Realise I am late to the party here - its defn corrosion inhibitor sludge.

One thing to bear in mind is that a diy flush (even at pressure) will still leave a reasonable amount of corrosion product on the inside surfaces of your rads and therefore only remove a certain amount of your problem.

If you are heating a big room replacing the radiator might be the only way to get the system working back the way it was designed.

L


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## nutts (May 8, 2002)

Thanks Lady 

But atm the heating performance of the radiator is crap, so will have to go with the flush additive and a flush I think... Can't afford to replace every radiator :-/



> Realise I am late to the party here - its defn corrosion inhibitor sludge.
> 
> One thing to bear in mind is that a diy flush (even at pressure) will still leave a reasonable amount of corrosion product on the inside surfaces of your rads and therefore only remove a certain amount of your problem.
> 
> ...


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## Sim (Mar 7, 2003)

Could this not just be that the system needs balancing?


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## t7 (Nov 2, 2002)

You prob will see an improvement just by flushing and draining and new inhibitor...However there will be a lot of sludge in the rest of your system so your flushed rad will prob fill up again over time.

Even if you replaced all the radiators youd get sludge transfer from your pipework into the rads.... :

In the long term your options are:
1) remove the sludge as fast as it forms by regular flushing and draining
2) use bigger rads than you need so you can live with the sludge 
3) do what we do in the oil business and buy stainless steel heat exchange equipment 

L


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## nutts (May 8, 2002)

I'm intending on flushing all radiators...

and I don't anticipate living here for much longer anyway.


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## Jac-in-a-Box (Nov 9, 2002)

Had the same thing before Christmas, tried these antisludge / flushing products, not very effective.

Cured by removing each offending rad and flushing with hosepipe.
Shut off rad at each end disconnect union at rad and allow water to drain into a container - remove any floor coverings around rad - the water will stain.
When flushing with hosepipe the muck that comes out will also stain patios and driveways.

Connect rads up and refill, drain down system. Do this several times. On final fill up add corrosion inhibitor.
Good hot rads and now a lot quieter!


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## nutts (May 8, 2002)

Presuming this is Dave, 'cos I can't believe Jackie took the Rads off ;D but then again, some chicks on here are pretty groovy  : 8)

Did you take each rad off after each refilling of the system to reflush each radiator more than once.



> Had the same thing before Christmas, tried these antisludge / flushing products, not very effective.
> 
> Cured by removing each offending rad and flushing with hosepipe.
> Shut off rad at each end disconnect union at rad and allow water to drain into a container - remove any floor coverings around rad - the water will stain.
> ...


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## Jac-in-a-Box (Nov 9, 2002)

You're right, it was me , Dave. Also couldn't be more true about Jackie, her only contribution to this evolution was to moan about the cold, the mess and how long I took Â :

Took all the rads off and flushed outside then refitted and re-filled system, run the boiler, vent rads and drain down.
Repeated twice (running the boiler was only to circulate clean water and shift muck out of pipes)

Final drain down , refill with corrosion inhibitor and all should be well.

Make sure you have some PTFE tape to seal unions on rad before final fill

It's dirty, and if your rads are large, knackering work!

Good luck , Dave


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## nutts (May 8, 2002)

;D

Looks like I may do the double flush, but I may use the flush additive first. The rads are typical new ones and not that heavy.

Cheers everyone!

Mark



> You're right, it was me , Dave. Also couldn't be more true about Jackie, her only contribution to this evolution was to moan about the cold, the mess and how long I took Â :
> 
> Took all the rads off and flushed outside then refitted and re-filled system, run the boiler, vent rads and drain down.
> Repeated twice (running the boiler was only to circulate clean water and shift muck out of pipes)
> ...


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