sweating close to thermostatic valve

homeboundJune 1, 2012

I am installing a Rohl shower mixer, etc. w/ 3/4 NPT connections, and two funtions (shower head + handlheld shower) with volume controls.

I will use adaptors to connect to the mixer, but how close after that can I sweat fittings without causing damage? Nearest elbows would be only 10-12" away. Thanks much.

I had started doing it in 1/2 cpvc but decided it's going to cut the flow down too much. Maybe I'll go with 3/4" cpvc instead.

BTW, the supplies to the bathroom are 1/2" copper.


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That's far enough away to not be a big concern. I'd recommend using a hot flame by using acetylene or MAPP gas rather than propane in order to speed up the job and reduce any risk. You can also wrap the mixer with a damp rag.

    Bookmark   June 1, 2012 at 1:20PM
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Thanks you. Good to know for next time. (I ended up using 3/4 cpvc for most of it.)

    Bookmark   June 1, 2012 at 9:25PM
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"I'd recommend using a hot flame by using acetylene or MAPP gas rather than propane in order to speed up the job and reduce any risk"

I would not recommend anyone using either of those torches until you get plenty of experience soldering copper.

Soldering, as defined by the AWS (American Welding Society) is the act of joining two pieces of metal by means of a fill metal that has a liquidous state of 800degF or less.

Brazing is defined as joining two pieces of metal with a fill material that has a liquidous state equal to or greater than 800degF but less than the liquidous state of the metals being joined.

A naturally aspirated torch that has a pre-combustion mix chamber such as a Turbo-Torch or Bernz-o-matic TS 4000 or Ts 7000 burning Propane produces a flame temperature of approximately 2150 - 2300degF and although it technically is a hotter flame, when those torches are used with MAPP gas it only increases the flame temp a mere 50degF. (hardly enough to justify paying 3 times as much for fuel).

In fact, the biggest problems that neophytes encounter when soldering copper is that they get the pipe and fitting too hot and burn the flux, thus leaving burnt flux ash and carbon in the joint, which prevents solder from flowing correctly.

Type SB lead free solder is intended to melt at approximately 550 to 650 degF and the flux will boil at 700degF.

The real key to soldering is first, clean both the pipe & fitting immediately before you install it. Do not be tempted to think its new copper so it don't need cleaning. Copper oxidizes very fast, so if its been more than 4 hours since you cleaned the fitting, odds are the copper has oxidized enough to make soldering difficult. (Clean it again)

Apply flux with a clean flux brush..DO NOT USE YOUR FINGERS. Using your fingers is a terrible habit that will result is to problems, 1. if you get in the habit of applying flux with your finger you can be sure it won't be long before your reworking a hot joint, and without thinking you will apply flux with your finger, resulting in a serious burn on your finger. (Take my word for that one, I made that mistake 20 yrs ago and the tip of my finger still shows where I branded myself).
2.The second problem with using your fingers is you introduce the natural oils from your skin, sweat or dirt onto the cleaned copper surface and that will make soldering difficult if not impossible(Do not touch the cleaned surface of copper with your fingers).

Flux brushes are cheap, when buying flux brushes get a half dozen or more, then if you happen to drop a brush you can toss it away and grab a clean one. Also make sure you keep the new flux brushes in a box or plastic bag in your tool box so they stay clean.

When solder melts it flows towards the heat, so when soldering a fitting apply the heat to the fitting and watch the end of the fitting. The first moment you see the flux bubble out of the joint pull your flame back away and touch your solder to the fitting on the opposite side from where you applied the heat and the solder will instantly melt and run around the joint leaving you a perfect joint.

If you continue heating the fitting and pipe after the solder bubbles you will burn the flux and odds are you will never get a tight joint till you remove the fitting and clean both the pipe & fitting again.

Next time your reworking something and you have old tarnished copper to remove, save it. Then take that old copper to the shop and chuck a piece in the vise and practice cutting, cleaning, fluxing and soldering a new fitting on it. It only takes a dozen or so practice fits and you will soon be soldering like a pro.

In the last 40 years I have amassed a collection of at least 30 different torches, some I bought, some I received as Xmass or Birthday gifts and many that were given to me from different plumbing suppliers wanting me to field test their newest bells and whistles.

Walk in any hardware store and you will find a cute little red or blue tin toolbox that contains a tank of propane, a propane burner/regulator assemble, a spark ignitor, solder, flux, and even a flux brush, everything you need, right? WRONG- Those torches were fine back in the days of 60/40 tin/lead solder, but they are not hot enough for type SB lead free solder and should be avoided at all cost. Then there is the cute little propane torch that has a regulator on the propane tank and a 4ft rubber hose to the torch head, again junk. What good is a 4' hose when standing on the floor and soldering copper overhead in the basement? While on the subject of junk torches, there are a number of cute little one handers that burn butane. In my estimation, butane was only marginally satisfactory in a cigarette lighter and surely not anything I want to try to make a living soldering copper with.

For soldering copper lines in a residential potable water distribution system my all time favorite torch is a Bernz-O-Matic TS 4000, but instead of using the long skinny propane tanks I prefer to use the short stubby tanks that they make for Camping equipment. Its the same fuel, at the same price, but the overall length of the torch is shorter making it much easier to handle in close quarters and the tank is nearly twice as wide so it is much easier to set it down quickly without it falling over, plus in my opinion it balances in your hand better with the short tank.

Bernz-O-Matic makes a TS 3000 pistol grip torch with the trigger start like the TS-4000 but when you pull the trigger it lights the flame and remains lit as long as you keep the trigger pulled (unless you manually lock it on), but as soon as you release the trigger the flame goes out, so you can set it down quickly and not worry about catching something on fire. The TS 3000 is slightly cheaper and it has the trigger start, but it has to be turned off manually, which can be awkward sometimes.

One thing I really like about the TS 4000 is that the tip stays cool. You can actually touch the tip with your finger the moment the flame goes out and it is only mildly warm, not enough to burn your finger or any structural materials it may come in contact with when you set it down.

The TS 4000 is also without question the most economical torch to operate. When your ready to solder you pull the trigger and instantly its lit, and the moment you release the trigger the fire goes out. No excess burn time. Typically I can solder all the joints in an average size 3br 3-1/2bth house with one tank of propane.

The TS 4000 may seem a bit pricey when you first examine it, but when you consider how rugged they are you would think them a bargain. I have one in my toolbox right now that I originally bought in a hardware store in 1986 and it still works fine. I have not even had to replace the peizo ignighter, although all the repair parts for it are available in nearly every hardware or big box home supply.

Now if you are running copper DWV pipe or commercial water lines 1-1/2" or greater, you may want to get a "Turbo-Torch double header or triple header, or an air-acetelene torch, but for anything short of that I doubt your will need anything heavier than a TS-4000 with propane.

    Bookmark   June 2, 2012 at 7:19AM
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Flame temp is not as important as using a large enough torch.

While 1/2 inch is usually not much of a problem on two joint fittings, 3/4 inch lines and Ts often require a larger torch than 1/2 inch 2-joint fittings.

    Bookmark   June 2, 2012 at 9:39AM
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