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[Sloppy_Snood]

While most know that plumbing with short radius copper elbows can cause significant pressure drops and frictional losses in plumbing designs, I did not know what is more advantageous (in terms of flow, frictional loss, pressure drops) from what I see as the remaining options to turn 90 degrees: two 45s OR a long radius copper 90.

Which is "better?"  Two 45s or a long radius copper 90?

All I could find in the Engineering Toolbox was basically equivalent length figures for individual fitting types.  Is this also meaning better flow with less equivalent pipe lengths per fitting? 

LINK:  http://www.engineeringtoolbox.com/resistance-equivalent-length-d_192.html

[mlappin]

Long radius ninety means one less joint to solder.

I usually like to say away from street fittings, more restriction especially in steel or cast fittings.

[Sloppy_Snood]

Long radius ninety means one less joint to solder.

Point taken on the reduction of soldered joints with the long radius copper 90s. 

That said, from a purely "better flow" perspective, slightly less "disruption" in the long radius copper elbow?  (Engineering Toolbox shows only a very slight difference)

More thoughts out there plumbing pros?

[willieG]

copper can be tight and neat and it gives off more heat than the pex. if you don't mind leaking heat where your pipes run

when my 1 inch pex enters the home I go straight into a 1 inch copper header and then down to 3/4 copper for my hot water tank and furnace exchanger  and then to 1/2 inch pex for floor heat (one loop) and 1/2 inch pex to a small exchanger in my fireplace

what leaks off the copper keeps the furnace room warm and dry

[slimjim]

45's are typically much cheaper but
have more resistance
look like crap
more labor installing
more chance of a leak

Long radius 90's win every time!