Copper pipe around corner

Hi. I've been sweating copper pipes for many years now with good success. Usually when I'm in a tight space such as near a stud and/or drywall I can just use a fireproof cloth to protect the wood and get the job done. Now for the first time I'd like to pipe between one wall and another with a 90 degree bend..

In my application I have a thermostatic valve with two independent volume control functions on one wall and a third function on the adjacent wall. I know I could route the pipe down to the crawl space beneath the house and then back up again at the other wall but I'd sure like to just pipe the 15" around the corner to the adjacent wall. Anybody done this before? What is the best method? Since this is a custom shower I plan on using 3/4" type L copper pipe to maintain flow rate. If necessary I could go down to the standard 1/2" but would like to avoid that. Studs are standard 2x4s that are doubled up where one wall butts against the other.

Earl

Get the wood wet before soldering. You have to have heat all the way around the fitting, so it needs to be even heat. You might want to solder first, and then slide the fitting over into the notch. It this case I put the heat right on the fittng.

Hi Terry, thanks.

Do you mean to solder one side of the 90 on, let it cool, then clean/flux the other side and put into a hole large enough to fit the bend, with the cleaned/fluxed straight segment inserted afterward?

No sure what you mean by "this case I put the heat right on the fittng." When I solder I always do that anyway. I first heat the inserted pipe about 3" away uniformly around the pipe, then move slowly in, when I get to the flux line I hold for a while, then I move to the fitting and heat that directly. Finally, I slowly move back and forth between the fitting. When everything is suitably hot (flux bubbling) I apply the solder. Is that what you mean? If so, the difficulty is that even with the 90 soldered on, after inserting it in the hole, a large part of the fitting will be surrounded by the wood stud.

Are you suggesting I make the hole much bigger to expose the fitting? I was planning a 1" diameter. I guess 1.5" hole would be no problem. Anything much larger and I'd start to wonder about structural integrity (i.e. code regarding allowable notching size). Can you be a bit more specific? For example, I understand getting the wood wet but is several passes with a mist sprayer sufficient?

thanks,
Earl

You need to do both ends of any fitting at one heating. Most of the heat on the fitting, not on the pipe. In sizes certainly to 1", by the time the fitting is hot, the pipe is also hot! Heat one socket, apply solder, by that time the other socket is almost ready...move the torch over and that one will finish in a jiffy./

I make sure there is plenty of room around the fitting so I can get heat on those sides. You don't want wood touching in this case.

I've been thinking about a future job where I have to do the same thing.

Is there any reason one cannot use a piece of Type L copper tubing to make a bend around such a corner? Without trying it, I don't know if the bend radius is possible.

It's not possible. I solder fittings in corners all the time. Make the notch big enough, and wet things down first.
And I've had some inspectors turn down soft copper inside for very little bends, much less tight bends.

Good to know- thanks.

Course, you could do this in 3/4" or 1" pex, and not put a fitting there at all! Although, the bend radius of larger pex might be a problem. -A pex is the most flexible and has the tightest bend radius. If you use a bend support, you'd be assured of no kinks and an acceptable corner. A sharkbite would work, but is way more expensive than an elbow! No soldering, though! Just make sure you've deburred the ends of the pipe or you you might mess up the o-ring seal.

Hi jimbo,

Thanks. Yes, normally I always do both sides at once. Perhaps I should digress to soldering method here. Is heating the pipe something I've been doing wrong all these years? I thought both the pipe and fitting had to be uniformly hot enough to melt the solder for a good joint. It seems that if I concentrate the heat on the fitting the flux will boil away before the pipe gets hot enough. When I first started (>10 years now) I had some bad experiences with solder boiling away too soon and my neighbor (who happened to be a plumber) told me that the joint wasn't getting hot enough. That's why I now use a lot of flux and start heating the pipe just outside of the fitting before moving in onto the fitting. It would be nice to confirm that concentrating on the fitting will conduct enough heat to the pipe. Perhaps I just wasn't using enough flux when I started and more flux was the solution.

In any case, it seems that the recommended method to get around the corner is to drill a large hole and, after wetting the bore down and assembling the parts, firing the torch (I use Mapp gas with the 'mixer' tip) into the hole toward the fitting. I suppose if I can do this from below the heat will conduct up and get everything hot enough to accept the solder. Do I have that right?

thanks again,
Earl

Generally, once you have the fitting hot enough, the pipe inside is, too. The key is hitting all around the fitting. Copper is a good conductor, so unless you have a big pipe, it will all be fine.

Terry said:

It's not possible. I solder fittings in corners all the time. Make the notch big enough, and wet things down first.
And I've had some inspectors turn down soft copper inside for very little bends, much less tight bends.

Click to expand...

So do you cut a square notch on the edge of the two studs so that everything is exposed on the inside corner of the 90? Will the inspector allow that vs circular holes in the center of the studs? If so, I didn't understand that from the first post. That would certainly make everything a lot easier! Perhaps I was making it more difficult that it is.

Earl

Often it takes as smaller notch to go around the corner with two 45s rather than a 90.