Which coupler do I need

[farside99]

Hopefully a fairly simple question, but I'm getting a bit confused as to what exactly I need.

I need to replace a 2 litre potable expansion vessel on my thermal store.

I've got a new one, but when I unscrewed the old one, the thread on it is 1/2, however the thread on the new one is 3/4.

What sort of connector/coupler can I get that will allow me to screw the new vessel into the connector and then straight into the existing pipe work?

Many thanks,

Peter

 

[picasso]

http://www.sourcingmap.com/34-pt-fe...gn=ukfroogle&gclid=COT-wc7Lh7wCFQrpwgodoW8AAQ

 

[farside99]

Thank you picasso. Much appreciated.