The drain valve is located near the bottom of the water heater tank. Many water heaters come with drain valves that are prone to leaks or breakage. Plastic cone valves (these have a cone-shaped handle) and plastic faucet valves often drip, freeze and/or clog with sediment. Even after only one use, plastic valves often leak. Also, because the drain valve is made of plastic, the threads on the valve are easy to cross-thread when attaching a garden hose to it.
More durable and cost-effective drain valves are made of brass. A brass hose bib looks similar to the average garden hose bib. A brass ball valve, which uses a lever to open and close the drain, is the most effective drain valve for flushing out a water heater tank. Ball valves have the largest opening found among drain valves; this allows you to flush the inside of the drain valve quickly and cleanly without clogging. And to close a ball valve, you simply move the lever 90° to the off position. With a hose bib, you will need to turn the handle until it is closed like the hose bibs attached on the outside of a house.
You can install a ¾-inch brass gate valve on most residential water heaters. A gate valve has a lever which runs parallel to the drain opening when the valve is open and is turned perpendicular to the drain opening when its closed. The purpose of a gate valve is to easily identify whether or not the valve is open just by looking at it. To do this, along with the new valve, you will need an adapter piece of brass plumbing with anywhere from a ¾ pipe thread to ¾ hose thread.
- Before you do anything, first turn the gas knob to pilot for gas heaters or unplug from the electrical outlet for electric heaters. Then run a tap in the house for at least five minutes; this will force new cold water into the tank, lowering the overall temperature, which will prevent any burns from the hot water in the tank. Once done, turn the cold water inlet near the top of the water heater off. The cold water inlet is the pipe on the right side as you stand facing the water heater. Next, open a hot water tap from any sink inside the house. Once the water stops running, close the hot water tap; this will prevent any air from entering the lines and relieves the pressure. All this preparation will allow you to replace the drain valve without emptying the water heater completely. NOTE: A pint of water or less may come out of the water heater after all of this.
- From this point on, make sure nobody uses any water while you are replacing the drain valve. To remove the old valve, turn the valve counterclockwise while simultaneously pulling it out. Six turns should be sufficient. Now turn the valve clockwise and continue pulling. Once you have removed the old valve, wrap the protruding nipple with Teflon tape. Now simply screw on the new drain valve.
Remember, adding a brass gate valve will allow you to more easily flush the tank and keep it free of sediment. A sediment-free tank produces hot showers.