Do Extra Copper Elbows Restrict Water Flow?

I'm replacing the wallboard and tile in my 3/4 bath's shower. The 43 year-old plumbing is 1/2" copper pipe. The hot water supply comes straight up out of the concrete slab, into a Tee, over a foot into a 90 degree elbow and up about 4 feet along a stud into the bottom of the shower valve assembly. Very neat and straight. The problem is that to make it this straight, the original plumber had to run the copper pipe in front of the 2" steel vent pipe between the Tee and the wall stud. The vent pipe is almost flush with the wall studs. Because of this placement, the copper pipe sticks out about a quarter inch beyond the wall studs. I guess they either hollowed out part of the wall board to accomodate the pipe, or they didn't nail the wall board all the way against the studs. The old wallboard is too far gone to tell for sure.
I want to replace the shower valve assembly and the hot water supply pipe to it because of its age and the fact that it's really green. I'd rather run the new copper pipe BEHIND that steel vent pipe so I can nail or screw the new wallboard (durock) flush against the wall studs. The only way I can see doing this is by adding 3 or 4 more 90 or 45 degree elbows to the copper pipe so it will go around the rear of the vent pipe and then up to the shower valve assembly. Or possibly bending a curve into the copper pipe, which I've never tried before.
I know the more connections in a copper line, the more the chance of a leak. But I'm fairly good at sweat soldering. What I want to know is if the extra elbows in the supply line will cause any restriction of the water, vibrations in the pipes or other problems when the shower is turned on.
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See if you can rent a manualpipe bender and bend it around obstructions instead. Are you sure the pipe won't push in a bit when you put up the Duraroc instead of going thru all that trouble?
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snipped-for-privacy@aol.com (Randd01) wrote in message

Nope, the copper pipe is running horizontally and it is right against that vertical 2" diameter steel vent pipe. It won't push in even a millimeter where the vent pipe is, and the vent pipe itself won't move. Bending a curve into the copper pipe might be feasible, though. Does this weaken the pipe and shorten its lifespan?
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Larry wrote:

The amount of pressure/flow loss feeding just the shower will be negligible. 45's are better than 90's.
If you get a length of soft Type "L" copper tubing, you *can* bend it to suit instead of using fittings.
Jim
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On 22 Oct 2003 12:24:03 -0700, snipped-for-privacy@hotmail.com (Larry) wrote: <snip>

Yes, each elbow will restrict the flow somewhat.
In a shower, however, the flow is most likely going to be more restricted by the low flow shower head or shower valve. I doubt 3 or 4 more elbows will matter, unless you have very marginal flow and/or pressure to start with.
Plumb it the way you want it, then test it before you close up the wall, which is a good idea anyway in case you find a leak.
The extra elbows won't cause vibration problems as long as the piping is clamped to the framing properly.
Oh, one more thing. Some of the new shower valves allow you to reverse the hot and cold inlets (for so-called back to back applications) by removing the cartridge, rotating it 180 degrees, and reinstalling.
Sometimes that makes the piping simpler. When I reverse one, I write hot and cold on the appropriate pipes with permanent marker to save some headscratching for someone in the future.
HTH,
Paul Franklin
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