Radiator not bleeding

20 Apr 2014
Reaction score
United Kingdom
My radiator is very hot at the bottom but cold at the top. I have removed the bleeding valve - nothing happens! No water or air! I don't think the bleed valve is blocked.
I'm totally confused. Please help!!!!
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if nothing comes out that is because nothing is coming in.
Are both valves turned on? If so that would mean your radiator is blocked
I have the same problem. The (only) two radiators at the top of the house are hot at the bottom & cold at the top. When I open the bleed valve, nothing happens - no air, no water.

Something to do with not enough pressure to fill the radiator? Header tank?

Would also appreciate any help!
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Sounds like the header / expansion tank is empty & the system is not filling with water. Check the ballcock isn't jammed. If the tank is full, check the outlet isn't blocked or similar.
this is not enough pressure in system.

If you have a sealed sytem- red canister in airing cupboard- open the water inlet until u are showing 1 on pressure gauge. Shut water inlet off- it will be like a washing machine valve- and turn it back on- bleed as required but top up to 1 again if needed.

When running should be between 1 and 2.
I also have the same problem with one radiator on the top floor of the house. The inlet and outlet valves are fully open, and the bottom few inches of the radiator get scalding hot after just a few seconds of the water starting to flow. I don't have a sealed system, the header tank in the loft is full, and all other radiators on both floors are piping hot at the top and bottom. There is no system bleed valve that I can find in the loft. Instead, I seem to have an expansion pipe that simply vents back in to the top of the header tank, above the water line.

The radiator in question is a 'half height' radiator, with the result that the bleed valve for every other radiator on the same floor is physically higher from the floor. Because none of these radiators have any air in them, I therefore know that the head of water in every such radiator is higher than for the radiator in question. With a full header tank, I am therefore at a loss why this radiator won't fill, and would appreciate advice, please.

Note that having had the problem, I removed the radiator and flushed it through with a hosepipe to check it isn't blocked. It isn't. I then switched off (closed the inlet valve) every other radiator in the house. This also made no difference.

Many thanks for any help given.
This is driving me nuts!
i am not a plumber or heating engineer.

question, when you flushed the rad did you open the bleed valve?

after refiiting the rad did you bleed it?
Hi. This is Paul, Im a plumber. This sounds very much like you have an air lock in the flow or return circuit pipes before this rad.
Solution. Close of all radiator valves on all radiators that are on that floor and run the heating as usual. After a while the rad will become hot. Bleed as usual then begin to open up the valves you closed on the other rads.
Good luck.
try removing bleed screw and sticking a pin through..have come across ones that were blocked :rolleyes:
try removing bleed screw and sticking a pin through..have come across ones that were blocked :rolleyes:
I've had a similar problem with my system. :(

and thanks to this forum, it all became clear, the air block also.......

It was puzzling me why most of the rads upstairs had cold spots in them, and when I was bleeding each one, by all methods mentioned here, such as turning all other rads off, then concentrating on the worst, and so on, that it didn't clear the air lock, then when I read this, and reading the commissioning handbook, it hit me like a tonne of bricks........ when I read the pressure gauge in the outdoor combi module, it read zero bar (or next to). So I re-pressurized the system, bled the offending rads, and all the rads are now roasting....... :p
Just read these suggestions. Re-pressurised my system, bled the radiators and then re-pressurised again. Bingo! Thanks a lot everybody, it seems to have worked a treat.
Just a quick note to say a big "Thank You" to everyone who chipped in with their advice. I had removed the radiator off of the wall so I could decorate behind it and when I put it back on the wall and connected it up again I could not bleed it until water came out...it was hot at the bottom and cold at the top, classic bleeding symptoms but the water just would not come out! The solution was re-pressurising the system after I read this forum.
My gauge and pressure cannister (I wondered what that thing was for... :) ) are up in the loft though so it took a while to twig. It read 0 Bar so obviously removing the radiator and draining the water out had caused a drop of pressure. Opening the washing machine type tap that connects to the the pressure cannister until it read 1 Bar again has done the trick nicely and I was able to bleed the radiator normally. Thanks again all...!

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