bathroom rad wont bleed unless i shut the valve

[bhm1712]

as in the title, when i want to bleed my bathroom rad, i can open the bleed valve and nothing comes out until i shut the rad off at the valve, then there is almost about 20 seconds of air coming out! all my other rads bleed normally

whats up with it?

 

[Gas2Air]

Have you tried taking the bleed out all the way? Maybe a blockage in the bleed hole. Does water escape? If ok, are you sure it's venting and not sucking air in?

 

[bhm1712]

im pretty sure its venting because after the air comes out water does.

 

[seco services]

im pretty sure its venting because after the air comes out water does.

so how is air then water coming out the bleed valve if you've shut the rad valves ?
if you've shut the valves water can't get into the rad.

 

[bengasman]

let me guess: it is an open vent system?

//www.diynot.com/forums/viewtopic.php?t=6026

 

[bhm1712]

i believe so

i have a Glow-Worm Space saver MK2, Gravity hot water and pumped Central heating, with a Wilo Gold pump. Open vent into the F&E tank in the loft, controlled by a Siemens RWB29 Programmer and Honeywell DT200 room stat. the system has no cylinder stat or motorised valves. There are seperate tappings for the hot water circuit and heating circuit at the boiler.

i have no idea how the rad is working like that, but im telling the truth. the rad will not bleed with the system on or off, unless i shut the rad valve. i can open the bleed valve all the way and take it out and nothing will happen unless i shut that valve. Every time i do shut the valve off and bleed, air does come out followed by water. The rad does get hot with the valve open and cools down with the valve off so i am sure the valve is working ok. I am trying to bleed because this is the only rad which gets a cold spot every 3-4 weeks

 

[swidders]

which valve do you close to get the rad to bleed - both or just one?

 

[bhm1712]

just the flow valve

 

[swidders]

Doesn't really make sense! Try closing turning the other valve down a bit to slow the "through" flow of water? Then try bleeding it with flow valve open.