Downstairs radiators keep going cold.

[dlicenceskydive]

Here is a problem for an experienced central heating expert that no visiting plumber has been able to solve.

We have an Ideal Mexico System boiler (12 years old) serving 11 radiators (9 new recently installed) and the hot water tank of course.

The problem I am experiencing is that with the central heating switched on, periodically some of the radiators (all the downstairs ones ) stop working and start going cold.The upstairs ones continue to remain hot. After a period of time (can be some hours) the downstairs radiators come back on again of their own accord. This problem has been going on for about two years now. Visiting plumbers have changed out 9 of the rads but still the symptoms persist.

Another thing I have noticed is that the header tank water is normally tepid and frequently the water there is so hot you can't put your hand in it. Nothing comes out the overflow. The plumbers who have visited can't give any explanation for this.

Anybody come across these problems before??
and have a solution?

 

[Plumbstar Tom]

are you sure nothing somes out of the over flow?

Which header tank is it? The F & E for the heating or the Cold Water Tank for the Hot water Cylinder?

 

[dlicenceskydive]

The header tank is the small tank in the loft that fills up the central heating system and this tank definitely is not overflowing. The water level is never anywhere near the overflow pipe. It is almost as if the cold water there is being heated by steam from hot water tank expansion pipe which overhangs this tank.