One bad apple

Hi
Hope someone can help. I have one rad in loft which although used to work no longer heats up. It used to work last winter but I frequently had to get the air out of it for it to warm up properly. When taking the air out water used to come out too.

Now a little bit of air comes out but no water and the rad stays cold except at the very bottom near the water inlet where it is warm especially if I give it a kick or two it warms up at the bottom briefly and then back to cold. The other side pipe with the thermostat stays cold.

I have a valiant combi system and the rest of radiators work fine. Any help appreciated.

Just remember a radiator has two valves, if one is closed or partially blocked it will stop the flow of water and not heat up. Your TRV may be stuck closed. If no water comes out when bleeding, then it could be blocked bleed valve or both radiator valves closed or blocked.
It would not take that long to close valves and remove radiator for cleaning and dismantling bleed valve.
As this is in the loft you could partially drain the system and remove the valves for examination or replacement. Remember to take note of the pressure in the system and when filling make sure the pressure is as previous.
Before replacing radiator I would bleed off any air at the valves, but this will cause the pressure to drop and will need bringing back to the desired pressure.
Take note though! I'm not a Plumber.

Having you been topping up the pressure when you've been bleeding? Highly doubt you have a blockage but you probably have a leak somewhere.

Thanks for the advice..no I have not been topping off pressure when releasing air from the loft radiator.The needle is just barely over one when I checked but I wasnt sure how to increase it..

Someone suggested I put some more water in the boiler whilst simulataneously releasing air from teh top radiator.. That's 3 flights of steps between loft and boiler

It may be that your system pressure needs to be set higher than 1.0 bar to take account of the height of the top rad above the boiler. What is that height in metres?

If it's around 10 metres you will need to maintain system pressure at 1.5 bar. 1.0 bar = 10 metres head = a column of water 10 metres high. So at the top of your system the pressure could be 0 or even sub-atmospheric which would cause air to be sucked in!

Also check Balancing in the Sticky section.