Cold Rad

[Briggsman]

Hi Forum, can anyone help. I have one cold rad in an upstairs bedroom. today I had another look at it, as its now coming into winter. I was going to try and remove some water from the it to see if it would dislodge any sludge (already added a treatment with no joy). This time though i opened the bleed screw to let some water out, and to test if it was blocked. Water came out and the two pipes (normally cold) going to the valve heated up. When i closed the bleed screw the pipes went cold again. The rad is the type that has one valve with the two pipes coming from it. Any help would be most welcome. Thanks

 

[pauls]

the pin in the trv could be stuck down. unscrew the top of the trv and gently tap the brass pin with a hammer till it pops back up.

 

[Winston]

Dont hit with a hammer use a pair of long nose pliers to see if you are able to pull up the pin. If however it is sludged up you need to get it out of the system.

 

[Briggsman]

Hi Pauls, the rad only has the old grey on/off valve. I did try tapping it before without any joy. any other ideas are most welcome. Thanks

 

[GreenArmy]

Close all rads except the cold one. Does it then get hot? If so return to other rads and just crack open valves until rads gets hot.
Basically balance the system.
If this dont work then you probably do have a sludged up rad.

 

[Plouasne]

This sounds like a micro bore system, 1 rad valve with 2 pipes to the valve

The problem could be the insert ( to send the water down the rad) has dropped of, and the flow of water is short circuiting, or that its sludged up

 

[Briggsman]

Thanks everyone for your help. I think its the micro bore system, when I removed the rad valve, I noticed the two rad internal pipes came out with the valve. Is this normal ?. They took a bit of persuading to go back in.

should have added, rads still cold

 

[migoplumber]

has the radiator ever been hot, the twin pipe rad valves have a screw or alan key 'by pass' in the body.

if you have hot water in both pipes, then as ploussane says the insert is faulty, or the washers in the bypass screw.

 

[Briggsman]

Hi Migoplumber, the rad was hot last year but then became cooler than the others in the house untill it didnt heat up at all. We had a new combi boiler fitted a 3 months ago but the rad stayed the same (cold). This morning i've noticed another rad upstairs is not as hot as it was, but the pipes going to it are, so I imagine this will be sludge.

 

[stevetheplumber]

sludge tends to start down stairs raather than on top flor rads can you turn off flow and return seperatly?

 

[migoplumber]

adjust the bypass screw to the total opposite of what it is now, either all in or all out.

 

[Briggsman]

Hi Shaun, Tried your idea but still no joy. i may try and take rad off the wall again. Steve, tried your suggestion also, but sadly with the same result. I'm wondering if the pump on the new boiler is powerful enough? its a Vokera Compact 29 HE. Supplying 8 rads four downstairs four upstairs. Have any of you had dealings with these?

 

[stevetheplumber]

Hi Shaun, Tried your idea but still no joy. i may try and take rad off the wall again. Steve, tried your suggestion also, but sadly with the same result. I'm wondering if the pump on the new boiler is powerful enough? its a Vokera Compact 29 HE. Supplying 8 rads four downstairs four upstairs. Have any of you had dealings with these?

its not going to be abything to do with the pump in the combi

If you can turn off flow and return seperatly you could try venting with each turned of in turn to make sure both pipes are clear with a combi your going to need some one else to open and shut the filling loop


think you need to get the rad of and flush it out with a hose checking that the distributor tube in the bottom is also clear

 

[Briggsman]

Thanks Steve, I'll give it a try