Radiator only heating at the bottom

napapa

Hey,
Having some issues with one of my bedroom radiators. First of all I replaced an old radiator, which I thought was damaged as it was only heating the bottom. I replaced with new rad and new valve fittings but same issue....tried open rad valve at top to remove air but i got no hiss, in fact I could remove the valve completely and nothing happened. I was expecting black dirty water but nothing no pressure at all! dumb founded.....all the other rads are fine

Any constructive advice appreciated,
Cheers.

Sparkpea

is it a sealed system or open vented? if sealed check the pressure, if open vented check theres water in the tank in the loft.

if its open, then the cold feed is likely blocked

heinbloed

There seems to not enough water in the radiator.

Before going further: is it a ('pressurised') closed central heating system or is it a ('non-pressurised') open system? And is there a circulation pump or is it a gravity based circulation?

napapa

I'm not 100% sure about this but I'm guessing its open vented, tank in the attic. I've an oil burner on the ground floor providing hot water. Only moved into house so getting to know the ins and outs as I'm doing it up!

heinbloed

Well, next step:
Turn the heating on as you're used to do. All radiator valves open.
Get into the attic and see if the central heating ('hopper-')tank is filled, if there is any water in it.
If it is dry we have the culprit.

napapa

sounds like a Saturday morning job ! I'll keep ya posted.
Cheers for the heads up.