Q&A / 

Pex Plumbing Tips

DEAR TIM: Money is very tight in this current economy and I just can’t afford to hire a plumber to install new water supply lines in my home. I’ve seen the pex piping and feel it's the way to go as there are no soldered joints hidden in the walls. Is it hard to install pex plumbing tubing? Can you share some secrets and tips? Am I crazy to think that I can be successful doing this? Dan G., Belle Mead, NJ

DEAR DAN: Not only is money in short supply right now for many, I feel it's going to get worse. This is going to cause many to jump in and do home repairs and remodeling not because they want to, but because they have to. There's lots of opportunity here - to make mistakes and to build confidence. Let's put you in the second group.

Here are two pex plumbing lines feeding into a tub/shower faucet. Note the stiff copper lines that send water to the shower head and the tub spigot. PHOTO CREDIT:  Tim Carter

Here are two pex plumbing lines feeding into a tub/shower faucet. Note the stiff copper lines that send water to the shower head and the tub spigot. PHOTO CREDIT: Tim Carter

First, understand that some cities and towns don't allow unlicensed people to work on the potable water supply systems in their homes. Keep in mind if your home is connected to a municipal water system, water, in certain situations, can flow out of your home and into the water mains outside your home. If you've made connections to the system that allow polluted water to flow into the water pipes outdoors, you can make many sick. It's serious business.

Let's assume you're allowed to do the pex plumbing installation work. I feel, with a little practice, you can be successful doing this major job. There are just a few areas where you'll need some sweet skills to ensure you don't have a leak.

Let's talk first about the many advantages of pex tubing and pex plumbing fittings. As you've already noted, since the pex piping is similar to electrical wiring, there are no joints in the pipe if you decide to install a separate pipe to each fixture from your main mechanical room where the water supply enters your house. That one characteristic of pex is an enormous time saver.

The pex tubing I've worked with, and had the best success with, is a special plastic that has a memory. Don't ask me how they figured it out, but when you stretch the material it fights to go back to it's original shape and size. This property allows the piping and little compression collars to grab tightly onto the knurled surface of the male adapter fittings. This is what creates the leak-free connections between the pex tubing and a manifold or a valve at the end of a run.

To stretch the piping, you need a special tool that has an expanding cone tip. As you crank the tool, this cone expands the plastic. The warmer the pipe is, the easier it is to accomplish this. Cold temperatures cause the plastic to react sluggishly. This means it expands slower and goes back to its original size slower.

These special tools come in both hand powered and a sleek cordless electric tool that's very handy. You'll have to get one of these tools to do the job, so give a serious look at the cordless tool. Once you've completed the job, you can sell the tool online if you desire and get back probably 65 percent of the price you paid for it.

The only place I can see you having problems is installing the two manifolds in your mechanical room. These are usually made from copper and have a shutoff valve at each port where you connect a water line. You'll have to securely attach the manifold to the wall and do some great soldering to connect the manifold to your water supply.

Some plumbers are moving away from the manifolds and installing pex piping like traditional water supply lines. In these cases you do end up with joints hidden behind walls. If you decide to install your system like this, you need to be very conscious of water pressure and friction losses. You'll have to install a 1-inch main trunk line that eventually downsizes to 3/4 inch and then 1/2-inch pipes that supply each fixture.

Be sure you follow all best practices when working with the pex piping. I would absolutely read any and all information that the pipe manufacturer has available. Be sure you don't pinch the pipe. Drill holes that are large enough for the pipe to pass through easily.

You also need to be aware of all the limitations concerning drilling and notching structural framing members. You just can't go start drilling large holes in floor joists. You can't notch floor joists. The building code often contains good illustrations that show you exactly what you're allowed to do without compromising the structural integrity of your home. Check what's on the other side of a wood member before drilling. You could penetrate a wire or a gas line!

Finally, I would highly recommend testing your skills before you advance to putting the pipe and fittings in your home. Create small test joints where you connect a pex pipe or two to actual shutoff valves. Then connect these short test pipes to your existing plumbing system. See if you have any leaks. Be sure you understand how to completely expand the pipe, rotating the tool as you expand the plastic and then quickly install the pipe and compression collar over the male end of the adapters before the pipe returns to it's original size.

Don't hope that you have leak-free joints. Remember, hope is the emotion of last resort. You hope for something when you can't control the outcome. In your case, with practice, you can control everything!

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