radiator hot at top cold at bottom

[dbroms]

any reason why the radiator is hot at top and cold at bottom?

any tips

[paul]

it's blocked inside.

[mcbrien410]

Paul, I had a radiator where the 'heat line' actually went in a curve from top left down to bottom right. The rad was just full of black iron dust. It was the 'dump' or 'leak' radiator and had not been flushed with the rads on the pumped circuit.

Chris.

[Roger Mills (aka Set Square)]

Is this just one radiator, and is it like this all the time? If so, the bottom part is blocked with sludge. When this happens, the cold part is usually triangular - almost full width at the bottom, getting narrower further up. The only real solution is to remove all the rads, take them outside, and give them a really good wash out with a hosepipe - taking care not to spill any indellible sludge on your carpets! Then make sure that there is plenty of corrosion inhibitor in the system.

On the other hand, if your radiators are warmer at the top than the bottom during periods for which the room stat has turned the system off - or TRVs have turned individual radiators off - this is perfectly normal, and is simply obeying the laws of convection.

[Blair]

The first check you should do is bleed the radiator to get rid of any air which causes this effect Then if there is no air then follow the advice the others have given Blair

[Andrew Gabriel]

If the return pipe from the radiator is cold, then the flow is too low and the system need balancing. If the return pipe from the radiator is hot, then the radiator is full of sludge as mentioned by others.

[Rob Morley]

Gas in the rad makes it hotter at the bottom and cooler at the top.

[Mary Jenkins]

Why are radiators hot at top cold at bottom

[alan_m]

Sludge and rust in the bottom of the radiator.

[The Natural Philosopher]

Because warm water rises.

[Brian Gaff]

At the risk of stating the obvious, hot air rises. Brian

[John J]

Did you miss the bit about the rad being hot at the top?