How to avoid overheating rough-in valves.

What is the best way to avoid overheating Hansgrohe Thermostatic shower/tub rough-in valves while sweating the ½†supply lines? These valves only have female threads. My dilemma is how to affix threaded male-to-sweat male fittings to the incoming water supply lines while keeping the valve plumb in the wall cavity. (The piping leading to the showerhead and tub will not pose a problem.) This is new construction in that the wood-framed walls encasing the valves are accessible from both sides. There are 5 valves at stake. I’m remodeling all three bathrooms in our home and really need some good advice.

Reading threads in the Shower and Bath forum (especially thread #1846), I came up with three ideas, but I'm unsure if any are the “best way†to proceed.

The first idea is to first assemble a copper threaded male-to-sweat male, a 90 elbow, and about 15-inches of vertical piping for each supply line. Affix both assemblies to the valve with Teflon tape and adjust the entire assembly, via the amount of tape used, so the fittings are properly tightened yet still lie in the same plane. Last, sweat couplings to affix this assembly to the supply piping lower in the wall cavity.

The second idea is to disassemble each valve, remove the heat-sensitive parts, cover the valve with a damp rag, affix the threaded male fittings, and solder away.

The third idea is to use copper threaded male-to-CPVC slip fittings for the supply lines, continuing with CPVC piping to get out of harm’s way, and then transitioning back to copper at a safe distance.

Please critique these ideas and inform an anxious amateur what would work best. This is my first post. Thank you!

Most valves will allow you to sweat the supply lines right into the valve and not use the threaded fitting at all. Eliminating the threaded fitting means one less point of failure in my opinion. Take a piece of 1/2" copper pipe and see if it fits inside. If you take the cartridge out of the valve, you should be safe.

I soldered my rough in this past weekend. I used 1/2 copper and didnt use threaded unions on my Danze rough in. There was a little play in the fit but nothing that made a difference. I removed all of the valves on it just to be safe. No problems.
Danze recommended not to adjust the thermo control prior to the flow adjustment since it was temp calibrated.
hope this helps

Thanks and more.

Dear Jim and Chris,

Thanks for your prompt reply. Half-inch copper pipe will fit inside the threads. I'll try it.

I'd also like to state what a great service these plumbing forums provide to the general public. Through Terry Love's forums, I've learned a lot of good tips that were never mentioned in any of 3 plumbing books I read. Perhaps needless to say, the advice one receives in most hardware stores (especially the big box retailers) is frequently of questionalbe reliability. By having a host of knowledgable people brainstorm a specific problem, the reader can either go with a consensus or incorporate the best elements of several experts and do so right from the comfort of one's home. It doesn't get any better. I live in a redwood forest in costal Northern California--about 20-miles from the nearest town of any size. I really appreciate forums like this.

One suggestion: Please don't delete past discussions. Many of your earlier threads, especially those involving installation techniques, will prove very helpful to new members.

Sincerely yours,
Carl

inlets

If the inlets are female threads, copper does not go into them. You solder a piece of pipe into a male adapter, then install the adapter into the valve. Finally, connect your piping to that piece of tubing. Do not convert to CPVC and then back to copper.