I'm hoping for your safety and your family, AND future homeowner's that you are attemping to do this natural gas run SAFELY with soft copper - - - regardless of how much sheet rock needs removed! Sounds like this would be first time you ever attempted copper run and didn't know about plating over dangerous locations where soft copper could be punctured later.
If you clicked the linked I posted above you'd see they show how to run copper gas line safely.
I've worked with copper more than an average home owner, even Silver Solder Gas copper line before! (Only with one of my Pro's over my shoulder watching the process after practicing it first)
I understand you would not run copper if you life depended on it, however the links above also show it as an industry standard. I would rather trust known sources of truth than someone posting on a forum. So please take the time and post a link to a known source of truth that backs up your information. Now if you can do that, I'll change my direction.
Only thing that makes sense is you got Free or cheap roll of copper tubing, as
you say that other products cost too much, and "Pro's told you to use copper . . . and you have 2 Pro's at your disposal who can help." Street price for 1/2" of copper coil that would cover 45 ft run that you say you need is $105 for 60 ft roll at HD:
http://www.homedepot.com/h_d1/N-5yc...gId=-1&keyword=1/2"+soft+copper&storeId=10051
Plus my main question was on how to make a 90 degree bend, not how to run or size the copper. (It's more like a 38' run)
I got the 60' roll from Menards for $65, 1/2 copper. on sale and it had a dent I will be cutting off.
Plus my neighbor has the same heater and ran a 45' 1/2" line and it works great. 45K Mr Heater
Why ask GJ in general if "you have 2 copper Pro's at your disposal" . . .?? Why not provide some pictures so better help could have been provided??
My Pro's have time for me on the phone, not to come over and help. Relatives (pipe-fitters) that don't live close at this time of the year.
Not sure what a basic picture of a wall will help... but it looks like this room. Think the back wall of 2x6's and the ceiling of 2x12's
The Heater copper gas line will be ran just like the copper gas line of the dryer, up from the basement of a split 2 level, but into the ceiling and then out to the attached garage.
Compare to 1/2" black pipe steel: $9 stick for vertical in wall, few bucks for elbows, and say $40 for long 40 ft run out to the meter (ie contractor grade 21 ft sticks of black pipe would minimize connections) - - - thus, I'm guessing total materials on black pipe steel would be say $60 total.
Almost what I paid for the copper. Plus the copper is much easier to run as I don't have to make a bunch of 90 degree angles and thus take down less Sheetrock and reduce my labor time. I can use a long bit and drill on the middle of the 2x12's to angle the run across the ceiling.
The GJers in MN or MI brought up SAFETY concerns for your planned copper run, especially if you don't have propane torch to make bends easier . . . or actually hire one of your "copper Pro contacts" as they'll know tricks of the trade in working with copper. I don't have any problem with copper in non-critical spaces when properly installed. Good luck and Be Safe.
As this is copper gas line, I'm do not think it's safe to use a torch and re-anneal it. Thus my original question on how to make the 90* turn.