combi worcester dripping

[young plum]

Hi not sure if my pic has posted but the problem is my combi keeps losing pressure other a couple of days.
After looking everywhere i have found the drip it is underneath the combi on the return pipe right at the top where the 22mm pipe meets a big fitting(don't no what it is called) but it has a service valve fitted in the middle and this is where it is dripping from..
Do i need another one or can i insert something to stop the leak
what is this fitting called

Thanks

 

[young plum]

 

[Softus]

Judging by the amount of PTFE tape all over everything the installation wasn't carried out by someone who knew what they were doing.

You need to replace the leaking valve. You should be able to order the relevant part from your local boiler parts supplier, e.g. Parts Center.

 

[young plum]

thanks what am i asking for it is the part where you put the screwdriver in to turn water on or off

 

[Softus]

Isolating valve.