Mod #91: Water Heater Drain Valve

Mod #91: Water Heater Drain Valve

Submitted on: 12/11/09

     Category: heating, plumbing
Mod Rating: 12345

(38 ratings)

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Mod Description:

Whether you are preparing your RV for winter, sanitizing the fresh water system, or performing maintenance on you RVs water heater, you have undoubtedly been frustrated by the lack of a drain valve on the water heater itself. Every RV water heater has a drain hole and most often a large plug screwed in to that hole. Removing the plug while the water heater is full can result in very wet clothes and water all over the place. To make draining easier, you can add a drain valve that replaces the plug. Draining the water heater becomes as simple as opening the valve, and you don’t get that instant rush of water that soaks your shoes.

Mod Difficulty:

In general, the drain plug on most RV water heaters has what’s called an anode rod. If you have ever drained your water heater, you know what this looks like. It’s a long rod that extends in to the water tank. What the heck is this thing you ask? If your RVs water heater has a steel tank, corrosive elements in normal water can eat away and corrode the tank. Over time, the tank could develop a leak and require replacement. The anode rod is used so the water attacks the rod rather than the tank. So if you replace the drain plug that has an anode rode with a simple drain valve that has no rod, how can you protect your tank?

Well it just so happens that there is a replacement anode rod that also has a drain valve. Yes, I know that’s awesome. So now you can both protect your steel water heater tank and have a simple drain valve for draining your tank much more easily.

If you are not too concerned about you tank corroding over time or have a tank that is porcelain-lined, fiberglass, or one made of aluminum, then there is another way to add a drain valve. You can use a plastic fitting that has threads on one side and a hose barb on the other. Fasten some high temperature hose to the fitting with a clamp and on the other end, fasten a common residential water valve. Voila! Instant water heater drain. You can also fashion a drain valve using other plastics fittings and a flexible braided hose. The possibilities are endless.

While your are modding your water heater tank, it might be a good time to flush and clean it. Over time, sediments from hard water can settle on the bottom and the sides of the tank. This can reduce the performance of the water heater and potentially cause bad taste. And since the water heater drain hole is about an inch above the bottom of the tank, simply draining it will not remove all the sediment.

But don’t fret. There is a simple tool that uses a high pressure water spray to clean the inside of the tank. It attaches to a common garden hose on one end and the other end is a long narrow wand that is placed inside the drain hole of the tank. The spray ensures the sediment is more easily flushed from the tank. Simply move the wand around the inside of the tank until the water flushes clear.

TipWhen choosing a replacement valve or fittings that screw in to the water heater tank drain hole, be aware that some metals are incompatible. For example, if you have an aluminum tank and use a brass fitting, corrosion can develop over time between the two dissimilar metals, making it difficult or impossible to remove the fitting. And plumber’s tape will only slow down the process. A steel tank and a brass valve will get along together as will a plastic or aluminum fitting with a fiberglass or aluminum tank.

ModMyRV recommends these parts for this mod:

Camco 11533 RV Anode Rod with Drain for Aluminum Water Heater
Camco 11703 RV 1/2″ Water Heater Drain Valve
Camco 11653 RV Water Heater Drain Valve Wrench
RV Water Heater Tank Flushing Tool

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3 Comments For This Mod

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  1. glmots

    Don’t forget to shut off the water heater long before your going to remove the plug, and let it cool down or you might get scalded with the hot water coming out of the tank.

  2. ModMyRV

    Good tip glmots! I always turn off the water heater well before draining it. I also turn a hot water faucet on until cold water runs out. This ensures the water heater tank is full of cold water if there isn’t enough time to let the hot water cool enough.

  3. Steve18080

    Also, you can make an extension (out of a male and female 1/2″ thread fitting and short piece of pipe) (or nipple and threaded coupler)….then thread the extension into the drain hole and put the valve on the end, this extends the valve out past the control valve, and keeps water from running down over the side of the trailer, plus you don’t need the tool to reach in…..Just make sure it is just short enough so you can close the lid

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