I have a radiator that gets hot at the top but is cold at the bottom. I’ve got a bloke coming round to have a look and service the boiler at the same time but I’d like to be forewarned about the cold rad before he starts work.

Any ideas what is causing it or could there potentially be a whole list of things?

If all of your other radiators are hot all over then suggest that this one just needs bleeding (removal of air as per hydraulic brakes) and problem will go away. If it is just a bleed its a simple fix and should take him minutes.

If you have a radiator key it is a job you can complete yourself fairly simply. (youtube or google for more detailed explantion)

HTH

Sunday

This rad is hot at the top and cold at the bottom. Wouldn’t air in the system cause it to be the other way round?

When was it last bled?

Hot at the top is odd.. When they need bleeding it’s more usual for them to get hot only at the bottom. Maybe it’s Rad sludge build up at the bottom stopping water cirulation there.

Is it half full of sludge, time to get your marigolds? 😯

It’ll be full of shit.

It’ll be full of shit.

This, one would assume, is a bad and expensive thing to sort then?

You can buy stuff to put in the system.. then you have to drain it I think.

Shut off the valves, drain the rad, dismount & takes it outside, flush it through with a hose pipe.

Very messy

Has someone added the wrong inhibitor to the system?

Shut off the valves, loosen the two joints then lift the rad off its bracket and swivel the top out and down to the floor. Drain it through the bleed screw. CLOSE the bleed screw and then disconnect the rad and carry it outdoors upside down for flushing with a hose. That way you won’t pour black sludge all over your floor.

It is caused by poor circulation either from a build up of ‘sludge’ or a badly balanced system.

Best to take radiator outside with a hose as others have said if sludge. You will probably be sold a power flush which may or may not cure the problem.

I’m not doing it, the blokes who we have used before are when they come to service the boiler.

Over the phone they said it could require balancing or a system flush, one being a lot more expensive than the other, and they would try a balance first.

I just thought I’d throw it to “The STW Hive Mind” to see what it thinks.

I’ve replaced all of the rad’s in my place as part of renovations

I couldn’t believe how much and how thick the black sludge was in the rads, the heating had certainly been neglected for some years before we moved in. The old chap had lived there for 56 years and basicly hadn’t maintained anything

I’d put money on a flush than bleeding/balancing too from the symptoms