Does 15mm copper have to reach right to the back of the fitting when soldering?

[Benjy]

I want to solder a 15mm end-feed elbow onto a straight run of pipe to join it up to a radiator. I've cut the existing pipe run just a fraction too short to come straight up to hit the radiator valve, but I'm hoping it could still work...

How important is it that the copper pipe is pushed all the way back into the fitting? Can it be inserted 8-10mm / two-thirds of the way in and still get a good joint?

 

[Scott_D]

Why risk it for the sake of a straight coupler

 

[Vip1969]

A long radius 15mm fitting might work or use Yorkshire which tend to be longer than end feed.

 

[Timmy D]

Use a coupling and male/female elbow. Or m/f 45 and standard 45.