Radiator: Hot at the bottom, cold at the top..

shady_creek

Help! One of my bedroom radiators is lovely and hot right across the bottom and upto about half way - but the top half of the radiator is cold.

I have tried bleeding it several time over the past few days [each time about 10-15 seconds of air escapes] but sadly this hasn't solved the problem.

Any ideas?

Reluctant_spender

When you bleed it does it solve the problem albeit for a short period of time.

shady_creek

No. Doesn't seem to make any difference.

bushy30

Are you trying to do this when the heating system is 'running' ?

If so make sure it's switched off !

Also do you know is it a gravity fed or pressurised system?

If gravity fed, your header tank could be dry, or the feed pipe could be blocked.

If pressurised (I suspect it isn't) then you need more pressure in the system.

Cheers

Bushy

shady_creek

It's run from a gas combi so I'm assuming it is pressurized. There isn't a header tank.

bushy30

OK with a combi system you should have about 1 bar of pressure in the system, enough for the water to expell any air, have you checked the system pressure? should have a gauge on the front of the boiler.

Cheers

Bushy

jonesMUFCforever

I think (I'm no expert!) that 1 bar pressure is too low - mine runs on about 1.3 to 1.5 bar/

bushy30

Most combi boilers will work down to 0.5bar, having a safe working range between 0.5 to 2 bar, again most will have a safety valve that will discharge excess pressure at 3 bar.