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Soldering the New Moen Valve — Install the New Shower Valve and Trim

Beginner4 hours

Part of project

Shower Fixture Installation & Replacement: A Complete DIY Guide · Step 3 of 5

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In this video

After removing the old valve, clean the ends of the existing copper pipes using sandpaper or a deburring tool. Dry-fit the new Moen Posi-Temp valve with new copper pipes and fittings. Ensure the valve is oriented correctly with the 'UP' marking facing upwards. Apply flux to all cleaned pipe ends and fittings. With fire precautions still in place, use a torch and lead-free solder to connect the new valve to the hot, cold, shower riser, and tub spout pipes. Once all joints are soldered, wipe them with a wet rag to remove excess flux.

Goal: Plumbing Pipes Installation

  • After soldering, immediately wipe the joints with a damp cloth. This cleans off residual flux, which is acidic and can cause corrosion over time.

Used in this video

  • Torch (Tool Type: Plumbing Tools, Power Source: Manual) — Heating the copper pipes and fittings to melt the solder.
  • Sandpaper/Emery Cloth (Tool Type: Hand tools, Power Source: Manual) — Cleaning the copper pipes and fittings to ensure a strong solder joint.
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FAQs

The project difficulty is listed as 'beginner' and estimated at 4 hours. Is this realistic if I've never done plumbing before?

While 'beginner' refers to the skills needed, plumbing can be unpredictable. Allow extra time, especially if you encounter old, stubborn fixtures or need to adapt to existing plumbing. Having the right tools and watching a few video tutorials beforehand will greatly increase your chances of success within the estimated timeframe.

My project lists a soldering torch, but I'm uncomfortable with soldering. Are there alternatives for connecting the new shower valve?

Absolutely! Many modern shower valves are designed for PEX or CPVC connections, which use crimp, push-to-connect (e.g., SharkBite), or solvent weld fittings. These methods are often more beginner-friendly than soldering copper pipes and eliminate the need for a torch, if your existing plumbing can be adapted.

What's the most common reason for leaks after installing new shower fixtures, and how can I prevent them?

Leaking typically occurs due to improperly tightened connections or damaged seals. Always apply plumber's tape (PTFE tape) or pipe dope on all threaded connections before tightening. Hand-tighten first, then use a wrench for another quarter to half turn, being careful not to overtighten and strip threads. Test thoroughly before closing up walls.

I can't find a specific shut-off valve for my shower. What should I do?

If your shower doesn't have dedicated shut-off valves, you'll need to turn off the main water supply to your entire home. Locate your main water shut-off valve, usually in your basement, utility closet, or near the water meter outside. Always confirm the water is off by checking other faucets before proceeding with any disassembly.

Transcript
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Now I am going to use the torch to remove all the old pieces because you want to save the copper pipe, remember don't cut it. Now that we have it like that you have to make sure everything is very clean before you solder because you are going to have only one shot for this. If you don't solder well and it leaks then you might have to cut. So now I just put it together, I measured the pipe cut, put my 90 degree my couplers. Make sure the valve is pointing up, the word up on top. And later on I am going to do my spot divider after I solder. So now I am going to solder all my fittings. You know nothing special. Take good time. So I had to lower my spot divider a couple inches so it looks kind of decent. So now I am done soldering. So after you solder and it cools off just make sure you clean the excess flux because if you leave it it is going to destroy the copper pipe and it is going to look bad and it is going to develop holes in the pipe.

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