Identifying name of valve on radiator which is leaking

[newhomeowner2]

We have a low pressure problem on our combi boiler and I have identified a small leak (one drop per two mins or so) from the top left sticky-outy bit of the bedroom radiator (the side opposite to the bleed valve). Can anyone tell me what this is called? It looks the same as the bleed value on the other side but it doesn't have a slit to turn a screw driver in it. It's flat and octogan shaped.
Can tighten this valve(?) myself to stop the leak and therefore get the boiler pressure back to normal?

 

[seco services]

http://www.towelradiator.co.uk/scripts/prodView.asp?idproduct=124

 

[bab]

just sounds like the chrome plug is leaking. unless very old it should just have a rubber o ring seal so if you tighten it a little it should stop unless the o ring is damaged. if it is u can use ptfe tape to create a washer instead but will need to remove the plug to do so. u will need to isolate the rad at each end with the valves 1st though and let pressure off at the air vent.

 

[newhomeowner2]

thanks! This nut shaped blanking plug looks like something I should be able to have a go tightening to stop the leak - is my theory correct?

 

[seco services]

yes unless it's loose the o ring is faulty

 

[newhomeowner2]

thanks Bab! I haven't got a tool wide enough but will try this weekend with father in laws! When you say I need to isolate the radiator at each end with the valves - does this mean turning them off at each bottom value?
Also is there any way to stop the leak in the meantime i.e by turning the valves off as it still leaks even if I turn the theromstat off on it.
My main aim is to stop the leak in order to get the boiler pressure back up to normal!

 

[newhomeowner2]

are radiator spanners one standard size? we don't have one. can I use another tool instead or will I have to buy one? seems a waste for such infrequent use?

 

[Bahco]

are radiator spanners one standard size? we don't have one. can I use another tool instead or will I have to buy one? seems a waste for such infrequent use?

£2.50

 

[bab]

turning off both ends should stop it unless the stat is old. BUT if the room gets cold it may open up a little. what make of trv is it as some need the lokin pins altering to allow shut off.( dont reckon u'll ave the trv cap that replces the head when rad removed ) if isolated the drip will stop but only when enough has dripped out to let the pressure down to atmospheric.