Slight leak from capillary air vent

[Jon24]

Hi, I was just wondering if anyone would be able to help. In the airing cupboard there is a section of pipe that tee's off from a pipe that links the diverter valve and hot water tank. On top of this pipe there is a capillary air vent.

The cap on this has started to leak very slightly down the sides rather than from the tiny hole. I was just wondering if changing the cap would stop the leak? I assume the seal has gone? Its done it before but sorted it self out, I assume the limescale sealed it.

 

[seco services]

Change the cap as you say the rubber seal has failed.

 

[Jon24]

Thanks, I assume they all have the same thread? Would be able to get one from B&Q then, i.e this: http://www.diy.com/nav/fix/plumbing...vent/PlumbSure-EndFeed-Air-Vent-15mm-11478160

 

[Charnwood]

I'm glad you linked to that page because I spotted something on there that made me guffaw:
http://www.diy.com/nav/fix/plumbing...bSure-Air-Vent-3-2mm-and-Bush-12-7mm-11477786
Now how does that fit in?

And why do B&Q have to such tw**ty sizes?!?!

 

[TicklyT]

It sounds like B&Q have decided to 'metricate' 1/2" BSP, and sent one of their goons out with a vernier caliper to do it!

I suppose 1/2" is near enough 12.7mm, even if 1/2"BSP actually has a major diameter of 20.955mm

Is that 12.7mm the same size as some of their other 1/2"BSP fittings listed as 19mm (the minor diameter of 1/2"BSP)?

Now I know why there's a blanking plug opposite the bleed valve on a rad - you remove that and use a long rad. key to open the valve.....