My bleeding radiator- any advice?

[davecon1]

Hi there

Can anyone shed some light on why I would need to bleed one radiator in particular every week.

It's a towell rail style radiator and I've noticed that the top rail is rarely hot. After bleeding it's piping hot but then a couple of weeks later it's cool at the top again.

Also I've noticed that a couple of rads in different parts of the house tend to hiss. They continue to do so until I turn the valve and then it stops for a while only to start up. I had heard that can be due to excess pressure but that wouldn't explain why it only applied to 2 rads and not all of them.

I wonder if the problem is connect- any advice on either issue?

 

[gas4you]

What system is it on? Open vent or sealed?

 

[bengasman]

probably corrosion

 

[davecon1]

What system is it on? Open vent or sealed?

It's a sealed system. I don't think it's corrosion as the radiators are quite new. One is a couple of years old and the other is about 6 months.

 

[gas_man_gaz]

could be small leak or hydrogen, is there any inhibitor in the sys?