Hep20 15mm exit from behind plasterboard advice

[Donkey Table]

Hi All
Im using Hep2o 15mm for the first time. I would like to exit behind the radiator at the midpoint. Whats the best exit back box fitting to use?

Single gang metal electrical back box is too small. The Hep back box appears only for 10mm pipe.

Open to suggestions. I want to fit the radiator later.

Thanks in advance.

 

[ShaunCorbs]

2g back box and 2x elbows and 2x street elbows

 

[Donkey Table]

2g back box and 2x elbows and 2x street elbows

Job done, thanks Shaun.

Ill leave out the bit where Ive had to refit 10mm with 15mm in order I may be able to use a heat pump if forced into it.