These questions are in context of a DIY solar water heater I am planning (another separate question). The copper pipes in question, are supposed to carry around hot water using thermo-siphon mechanism.
Are there some specific reasons why people recommend bending long copper pipes, instead of cutting them into sections and joining them using U-joints, elbow-joints etc. ?
Also, can such joints be made reliable (as in leak-proof, while withstanding water pressure) without brazing them ?