Replace that Plastic Water Line on Your Humidifier!

Here’s a little project you may want to look into. It’s very inexpensive, fairly easy to do, and could save you a lot of money and headaches down the road. I learned the hard way. Saving a couple of dollars led to a very expensive and unexpected service call.

Check the water supply line on your furnace’s humidifier. If you’re not sure where it is, look at your water heater. There are two copper pipes connected to the top of it. There will be a thin water line fastened to one of those copper pipes, and it will lead to the humidifier, which is usually attached to one of the ducts near the furnace.

It’s possible that the thin line may not be near the water heater. You need to look along the water pipes for a valve with a smaller water line coming out of it leading to the humidifier.

Now examine that small water line. Is it bronze and made of copper, just like the main pipes connected to the water heater? If so, you may as well stop reading. Well, wait a second. Give it a quick once-over to make sure it’s not leaking. Then you can stop reading. You’re all set.

However, if that thin tube is another color and made of plastic, you should definitely replace it with copper, and here’s why. Those cheap plastic lines can break easily, and they usually do at the worst possible time. When they fail, anything can happen, from a flooded furnace room to an out-of-commission furnace or water heater, or any combination.

As I said, I learned the hard way. On a frigid night in January, the house began getting far too cold. Upon checking the furnace, I discovered the plastic humidifier tube had burst, spewing water everywhere. It was a mess, but that wasn’t the only problem.

Water from the broken line had sprayed onto an electrical box on the furnace, knocking out the furnace completely. Needless to say, obtaining emergency furnace repair at 11:00 on a Saturday night with the temperature below zero is not a bargain. As it turns out the technician had a replacement part with him and was able to get the furnace running. I parted with some dollars, but I had little choice. That’s not the time for comparison shopping, and my knowledge of how furnaces operate is limited at best.

This could have all been prevented by using copper instead of plastic for the humidifier’s water supply. Here’s how to go about replacing the plastic one.

First, there is a valve (usually a saddle valve) where the plastic line connects to the copper pipe above your water heater. Turn that valve clockwise to shut off the water. Then grab a wrench and disconnect the plastic line by loosening its nut and then pulling the line out from the valve. Remove it slowly, as a slight amount of water may come out, so be ready for it. If you get a steady spray, though, you either have a defective valve or turned it the wrong way to shut it off. If you need to replace the valve, search for “saddle valve” on the internet, and you’ll find many good articles on it. Yes, it’s time for a groan; another unexpected event during a repair. But look at the bright side. At least you discovered the faulty valve before it caused any more serious problems.

Remove the plastic tube from the humidifier. Straighten it all out, measure its length, and take a piece of it to the hardware or home improvement store. Seek out a salesperson in the plumbing department.

Ask for some flexible copper tubing the same length and thickness as the plastic one. They will cut the tubing for you. If you have a tubing cutter at home, you might want to buy a slightly longer piece, since you can cut it for a more precise fit if you wish. You’ll also need two new compression fittings to attach the new copper tubing. They’re easy to install – all you do is slide the nut on the end of the tubing, and then the little ring after it. The person assisting you at the store should be able to show you how.

When you’re ready to install the new tubing, follow roughly the same path the plastic line took. But don’t attach either end just yet, or you can risk kinking it. You’ll probably have to bend the tube gradually as you go, but do so with extreme caution. Even though it’s flexible and bends easily, don’t make any sharp bends. Make gradual curves instead. If you bend it too far it will kink, and once that happens, forget it. It’s not worth the risk. It may not leak right away, but you’re asking for trouble. Get another copper line.

Once you get the line bent to fit, slide the nut and ring onto each end. Make sure the nut goes on first, so the ring is inside it. Connect the line to the valve above the water heater. Insert the tubing as far as it will go. Then slide the ring and nut up to the valve, screw the nut into the valve, and tighten it. Do the same at the humidifier end.

After it’s securely tightened, turn the water back on at the valve and check for leaks. Leaks are usually caused by a kink in the line, an improper connection, or a loose connection. Any leaks must be taken care of immediately.

That’s it. Your new copper replacement water line should give you years of worry-free service.

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