Leaking dual fuel towel rail

[mike222]

Hi, hoping someone can help. We have a dual fuel towel rail, i.e. connected to the central heating, but with an electric element in one of the "legs". The bottom of the other leg is leaking around what I assume is a blanking plug. This plug has a large hex socket, and I've tried tightening it up a little, but it is still leaking sometimes during the day. It seems to leak when the radiator is cold, so I guess it seals itself when it expands with the heat.

Do I just shut off the valves, drain the radiator and wrap some PTFE tape around the thread, or is there something I've missed?

Attached are photos of the right-hand "leg", which is leaking, the left-hand "leg", which has the electric element, and the underside of the leaking plug.

Also the lockshield valve seems to leak when it's closed or fully open, but seems ok when it is open a few turns. I noticed this when I switched from electric heating (when both valves were shut off) to the central heating.

Any help would be appreciated.

 

[Ric2013]

Are you positive that the plug is leaking? There would appear to be some some limescale on the underside of the adjacent compression joint which might suggest that the water is running down from the joint onto the plug when cold and evaporating at the compression nut when hot, thus leaving a limescale deposit. Hard to tell from a photo, but worth a check.

 

[mike222]

Are you positive that the plug is leaking? There would appear to be some some limescale on the underside of the adjacent compression joint which might suggest that the water is running down from the joint onto the plug when cold and evaporating at the compression nut when hot, thus leaving a limescale deposit. Hard to tell from a photo, but worth a check.

Thanks for the suggestion. I've now checked the compression joint, but it's not leaking. The apparent limescale seems to be just an untidy joint. The leak is around the plug, and it seems to happen only when the radiator is cold.

 

[Ben-gee]

One point to note - when using the electric to heat the towel rail, don’t close the rad valves as you’ll have no room for expansion and this may well have caused your leak (eg past an oring).
On an electric only towel rail the fluid only fills about 90% of the rail, to allow for expansion. When dual fuel it will be 100% full.

 

[mike222]

One point to note - when using the electric to heat the towel rail, don’t close the rad valves as you’ll have no room for expansion and this may well have caused your leak (eg past an oring).
On an electric only towel rail the fluid only fills about 90% of the rail, to allow for expansion. When dual fuel it will be 100% full.

Thanks - that's interesting. I did close the valves when I switched to electric for the summer but I opened the bleed valve slightly to allow for expansion, following instructions I found on several websites. If you keep the valves open when using electric don't you end up with the heated water flowing out into the pipes?

If it did cause the leak, how do I fix it?

Thanks