A rusty or cruddy radiator?

[geordief]

Wondering what could be the problem with my radiators.

They are downstairs and so I doubt there would be an airlock.

When I open the bleed valve on the top (with the inlet and outlet valves closed ) there is a good influx of hot water when I open one of the valves.

When I close that valve and open the other ,there is a good influx of cold water (from the other direction now) that comes out of the open bleed valve.

But when I close the bleed valve (maybe not a "valve";it is a small round screw that goes into to top of the radiator) and open both inlet and outlet valves the radiator does not heat up.

Any ideas ? Could there be a blockage in the pipes? A blockage in the radiator even though it accepts water from either direction?

 

[CBW]

Are the pipes to the affected side hot? What type of valves on either side, eg TRV? Could be piped up incorrectly. What type of heating system is it, eg Combi boiler, sealed system or open vent (tanks in loft)?

 

[geordief]

Unless I open up the bleed screw there is zero heat. When I do that the hot water comes through once I have filled up ,say half a bucket.

After I close the bleed screw all the heat (and presumably circulation) disappears.

The boiler I have only feeds these downstairs radiators (well that's a lie;there are two pumps attached to the boiler ;one goes upstairs to the hot water tank and the other pump feeds the downstairs radiators)

The boiler receives its water from a tank about 10/12 feet above it .This water seems to feed into the pipes and not directly into the boiler itself (I assume that is normal)

If the system overheats ,that is where the steam comes out (but it is not doing that at all ;just to show the setup)

The system is seriously ancient but other radiators(the one's we need) are working fine.

At the back of my mind is the need to maybe let sleeping dogs lie (or call in a professional) so as not to disturb the functioning of the radiators we use all the time for the sake of fixing this problem (they did work in the past and it would be a great benefit actually to get them going again)