Towel rail cold spots.

[VickyBH]

I had two towel rails fitted about a month ago. Both were working well but recently I noticed a bit of cold spots towards the ends of the bars. I tried adjusting the valves by turning them several times in each direction, but the cold spots have now spread even further. Could someone please help me understand how the valves work to resolve this issue?

The photo shows cold areas in red circle, both manual valves and other areas are still hot.

 

[Murdochcat]

The key issue with designs like this is that there is no flow at the end of the horizontal bars - as you have found out.

How long is the radiator on for ?

 

[JohnD]

Check with a spirit level. Are the horizontals?

 

[VickyBH]

I live in a building where central heating hot water is provided 24/7. So it's been switched on 24/7 for about a month. I will try to borrow a spirit level, but it looks pretty levelled so far.

I called the manufacturer and they say to close the lockshield valve a bit more, does it sound right? I assume the locksheild valve is the one fitted on the return flow pipe?

 

[Madrab]

It's air in the rad that's trapped at the end, see if you can bleed it out. Bloody stupid looking things IMO and such a design faux pas. Why not put a recessed bleed valve at top right hand end ... you know I really hate manufacturers sometimes.

 

[ChrisJP]

With these 4 dead end bars, they'll always be cooler than the two upright bars which have water flow through them. The deadends will get warm by conducted heat from the uprights but will never be hot. I think this is a case of design taking precedence over function.

 

[VickyBH]

If there are airlocks at the deadend of the horizontal bars. Do you think it's possible to get rid of it by connecting a drain hose to bleeding valve, let each of flow and return drain until radiator is hot?

 

[ChrisJP]

I'm not clear what you are proposing but it's possible that the extended bleeding you'd be able to do with a drain hose connected to the bleed valve might dislodge some air.
However, even if the dead end parts of the towel rail are completely full of water, they'll never get as hot as the rest of the radiator because there can be no water flow through them. You'll get some heat conduction through the metal, and a little through the water itself, but I think the dead legs will stay pretty cool whatever you do.
As I said, I think this is a case of design taking precedence over function