Some of My radiators aren’t getting hot (others are) just like warm. When I bled them the water is clear. Could they still be gunked up and have clear water.

Got some x400 but now wondering if a waste of time.

If they were working before then check your circulation pump and motorised valve to make sure they are functioning properly. Your pump might be running but not working effectively which is why some rads are getting warm and others aren’t. I had an issue with my pump last winter and as the pump was making a noise I assumed it was working fine, but upon closer inspection I realised it was not working very well. I swapped out the pump and all was well again.

Also if you bleed the rads the water that comes out of the bleed screw will always be clear…the sludge sinks to the bottom of the rad. Have you got a magnetic filter? If not it is a good idea to get one anyway. Brilliant things. When I got one fitted the first couple of services the sludge it captured was unbelievable…I’m amazed my system was working at all. After the first two or three services the water in the system is crystal clear and the magnetic filter comes out pretty clean every year. Probably why my pump packed in…pumping all that sludge around for years can’t have done it any good.

I assume they worked at some point(!) but it’s a new house (to me) but old radiators. I can hear the pump running and it does make more or less noise if I change the speed setting. I’ll give the valve manual switch thing a waggle and then give the x400 a go before replacing stuff. Ultimate plan is to replace all the rads but not necessarily the pipe work so would be good to know it works so as to know what needs doing.

are they warm at the top or bottom or both?

i bet its a combination of things, sludge, pump and balancing. Where on the circuit are the rads – front middle or end? If there is sludge at the bottom, the water could just as easily be by passing as the balncing then favours the other rads. If it’s an old system its always worth removing the rads (really not as hard is might seem) and pouring the crap out and blast a hose through. Of course inhibitor will be needed after..

Try turning off all of the ones that do work to see if heat gets to the ones that currently dont.

If yes, you need to balance all of the radiators.

Is the pipe before the radiator hot? Might just be a sticky stat?

Have you checked the valves are fully open?

Try turning off all of the ones that do work to see if heat gets to the ones that currently dont.

If yes, you need to balance all of the radiators.

This, and if they have TRV’s take the head off and see if the pin moves – youtube shows a few good videos on this if you dont know how.

In term of removing did take one off and seemed to be largely clear but obviously doesn’t mean the others are. Although it does seem to work a bit better now so must have helped somehow. In terms of removing them, there’s quite a lot and some of them are pretty big rads (9ftx2ft doubles) so lower effort preferred!

Not sure top / bottom will check tonight, I think for some it’s oneside of the double is luke warm and other barely warm.

Only a couple have TRVs and they seem to heat the others are single entry jobbies (argrrghgh)

It’s cold bottoms – the rads that is. So something has settled in the bottom I assume. Will stick some x400 and see what happens.

if its cold at the bottom then its not getting the flow.

youll need to balance your rads.

If you doing a flush while your doing it go around and turn everything off and then do one rad at a time. Maybe even take it off the wall.

I wouldn’t go careering in trying to fix stuff before you know what is wrong. You’ll just end up introducing more problems if you’re not careful. Some thoughtful exploratory work will save a lot of problems down the road. The chances are your rads are balanced in a ‘no sludge’ system. Re-balancing to take into account restrictions due to sludge is not fixing your problem.

Maybe just take one affected rad off the wall initially and empty it to see if a load of sludge comes out then you’ll know sludge is the problem. If it is i’d favour the approach of going to each rad in turn and emptying out the collected sludge then chuck in the chemicals…remove what sludge you can altogether then treat what you can’t remove.

If no sludge or a usual level of sludge then lock open your motorised valves and see they are opening correctly.