one radiator with sludge!

[jellyjiggles]

All the others are working well. I want to avoid power flushing as we don't have a lot of money and I'm afraid it will burst pipes.

Can I just remove the one radiator and flush it out with a hose?

yes. Drain down the system, put bowls under the ends of the radiator concerned. Disconnect, lift off wall, take outside and flush through. You could also consider replacing it, they aren't that expensive.

(much heavier and messier than that but you get the idea!)

power flushing won't burst pipes but is of limited use.

If you can do basic plumbing, you can do a chemical clean of the whole system using Sentinel X400 or similar. It loosens sludge and sediment so you can drain and rinse it out. You need access to the drain cock and to the feed and expansion tank in the loft if there is one (if not, it is less easy).

The chemical for the clean and for the final fill are about £15 each and it will probably take you less that two half-days, a few weeks apart.

Hosing out is very effective for sludgy radiators.

How do you know it is sludged? Is it cold in the middle, top, bottom, or all over?

As pj says what are the symptoms and who said sludge?

So we've taken radiator off, flushed out. It was clean. Radiator in question is cold at bottom (middle) never gets very hot. Outlet pipe is much colder. Inlet pipe is very hot.

We had the system chemically treated 9 months ago. This is a new problem. I've bleed all radiators.

turn all the others off. Does this one heat up?

Yes but still not as hot as the others get.

When I say yes. The middle bottom doesn't. It just gets warmer because of the metal heating up. It's about a four foot long, 3 foot high single radiator.

how hot do the sides and the return pipe get, with all the others turned off?

Inlet is very hot. Side of inlet gets warm-hot ( not as hot as inlet or other radiators), outlet side lukewarm including outlet pipe.

It has improved with thermostat off, after flushing radiator and bleeding other radiators. There wasn't much air in the system tbh

So I've bled radiators again and yet more air has come out. I've turned off all radiators except the one in question and it's finally getting very hot . First time so we've obviously sorted out some of the problem.

Now how do I get all radiators to work well together?

You need to balance them so that water flows through all of them at about the same rate, rather than mostly flowing through the easiest path and missing out the more difficult ones.

There is a very long and tedious post I wrote about radiator balancing, if you search Property & DIY; Balance; PigletJohn, it will come up.

If the water that came out of the bleed screws has turned black, it may be that you disturbed some accumulated sediment. Consider fitting a system filter which will trap circulating particles before they can accumulate into a blockage. It will cost about £100 plus fitting and is very worthwhile on an old or open-vented system. If the water is brown, you have a more worrying problem.

Thankfully the water is clean! I'll find the post. Thanks