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How To Unclog a Drain Valve: 7 Ways to Get the Water Flowing

 
 

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When your water heater won't drain, the most likely cause is a clogged drain valve. This is  generally the result of excessive sediment build-up within the tank. When water is heated, the minerals in the water separate and settle to the bottom of the water heater. If the tank is not drained routinely, the sediment will not only reduce the efficiency of the unit, but it can also clog the drain valve and trap the water within the water heater.

The severity of your clog can vary from a minor inconvenience to a major issue. Left unattended, it will ultimately result in the need to purchase a new water heater since the sediment will break down the inside of your tank and create an unrepairable leak.

7 Methods to Unclog a Drain Valve


Determine if Your Drain Valve is Clogged

The first step is to determine if your drain valve is actually clogged. Follow these steps:

  • Turn OFF the fuel source to your water heater (Electric: Turn off the circuit breaker / Gas: Turn the on/off control knob to off).
  • Connect a garden hose to the drain valve, and OPEN the valve.
  • OPEN a hot water faucet inside your house (leave open) to eliminate the negative pressure within the tank.
  • If the water drains and turns clear, your valve is not clogged.
  • If the water trickles or does not drain at all, the valve is clogged.
 
 

Caution: There's a good chance that the water in the tank is hot. If this is the case, you should take safety precautions to prevent being burned. Always wear work gloves and safety goggles when attempting to drain a water heater. Also, the water should be cooled before draining. Here are several ways to cool the water inside the tank:

  • Disconnect the gas or electric supply to the water heater and allow it to sit for up to 24 hours.
  • If your water heater is not completely clogged, drain whatever water you can from the drain valve and leave the water inlet valve open. This will allow cold water to enter your tank and dilute the hot water. The fuel source (gas or electric) should be turned off.
  • If your water heater is completely clogged, you can open the hot water faucets in the kitchen or bathroom to draw hot water from the tank. Leave the cold water inlet valve open to dilute the temperature of the hot water. The fuel source (gas or electric) should be turned off to prevent the water from reheating.

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How to Unclog a Water Heater Drain Valve

There are a number of different ways to drain a clogged water heater tank, and of course, the severity of the clog plays a big role in determining which method works. We recommend starting with the easiest and working your way down the list.

Remember, the water in the tank is most likely HOT, so to prevent burns, follow the safety recommendations outlined above.

Before starting, turn the power source to your water heater OFF. Electric water heaters: Turn off the circuit breaker - Gas water heaters: Turn the on/off control knob to off).

Pocket watch an chain

Wait

The first method to try if your drain valve is clogged is to simply wait. Sometimes the weight from the water within the tank will clear the clog on it's own. Here's what to do:

  • Leave the drain valve open with the hose attached.
  • Close the hot water faucet inside the house.
  • Wait for an hour or so to see if the tank starts to drain. 

Wire Coat Hanger

If waiting didn't unclog your drain valve, the next thing to try is the wire coat hanger method.

  • Close the drain valve and remove the hose.
  • It's a good idea to place a small bucket or a few towels under the drain valve.
  • Use a stiff wire, such as a wire coat hanger.
  • Open the drain valve and insert the wire through the valve opening into the tank.
  • Move the wire in a circular motion to attempt to loosen the debris.
  • If you are successful, the water will begin to flow out of the tank.
  • Once you have a good flow of water, you can turn the valve off and attach a hose so the tank can finish draining.
  • The valve may clog again before your tank has completely drained, but you can simply repeat the process.

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Hose Stomp

If your drain valve still won't drain, try stomping on the hose.

  • With the hose attached to the drain valve, step firmly onto the hose about 2-feet away from your water heater.
  • If the source of the clog is from sediment, an air bubble will be forced back into the tank and unclog the valve.
  • Don't be suprised if the drain valve clogs again while you're draining the tank. Simply keep repeating the process until the tank is completely drained.

Back Flush

If none of the above methods worked, it's time to try back flushing your water heater. Here's how:

  • Use a wash machine fill hose. These hoses have a female connection on both ends.
  • CLOSE the drain valve and connect one end of the wash machine hose to the valve. Attach the other end of the hose to a nearby washtub faucet (they are frequently threaded) or a garden hose (and attach the garden hose to an outside faucet).
  • Turn ON the water to the faucet.
  • OPEN the water heater's drain valve and allow the water to flow into the tank for 10 to 15 seconds.
  • The water from the hose should push the sediment away from the valve and clear the clog.
  • Turn OFF the water at the faucet and CLOSE the drain valve. Disconnect the hose from the faucet (leave the hose connected to the drain valve or replace the hose with a garden hose).
  • OPEN the water heater drain valve and drain the tank.
  • If the water still won't drain, your clog may be too sever or your valve is defective and you'll need to replace your drain valve.

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Replace the Drain Valve

If backflushing didn't work, then it's time to replace your drain valve. If done correctly, it IS possible to change the drain valve while your tank is full of water. Here's how:

  • Purchase a replacement drain valve (perferably brass).
  • Use teflon tape on the threads of the replacement drain valve.
  • Double check that ALL faucets in your house are CLOSED. This will create a vacuum in your water heater and prevent the water from "pouring" out.
  • Place a bucket and towels under the drain valve.
  • Use an adjustable wrench to loosen the drain valve.
  • Slowly unscrew the drain valve. Be prepared for some water to pour out of your tank.
  • Even if your tank is clogged, you will most likely have some water escape. However, if the issue is a faulty drain valve, you most certainly will have water.
  • Immediately insert the new drain valve. This should only take a few seconds.
  • Connect a garden hose to the new drain valve and drain your tank.
  • We recommend, that if you're going to go through the effort of changing your drain valve, you should consider replacing it with a ball valve (see below). You'll never need to worry about your drain valve clogging again.

 

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Replace the Drain Valve with a Ball Valve

A ball valve is much larger than a standard drain valve. By replacing your drain valve with a ball valve you'll not only unclog your tank, but you'll also prevent sediment from clogging it in the future. Here's how to replace your drain valve with a ball valve:

  • Purchase a brass 3/4" Ball Valve and two 3/4" dielectric nipples. (The nipples are coated with plastic to prevent rust). Each nipple will attach to one side of the ball valve.
  • Use teflon tape on the thread of the nipples that screw into the the ball valve.
  • Keep in mind that the handle of the ball valve should open AWAY from the tank. Use the teflon tape on the second side of one of the nipples (only 3 of the 4 threads on the two nipples will be lined with teflon tape).
  • Double check that ALL faucets in the house are CLOSED. This will create a vacuum in your water heater and prevent the water from "pouring" out.
  • Place a bucket and towels under the drain valve.
  • Using an adjustable wrench, loosen the drain valve.
  • Slowly unscrew the drain valve. Be prepared for some water to pour out of your tank.
  • Even if your tank is clogged, you'll most likely have some water escape. If the issue is a faulty drain valve, you most certainly will have water.
  • Immediately insert the new ball valve. This should only take a few seconds.
  • Connect a garden hose and drain your tank.
  • Once your tank has drained, you should either replace the ball valve with a regular drain valve or remove the handle for safety. The handle could inadvertently be opened and drain your tank. This could cause water damage and/or serious burns.

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Move Your Tank Outside

If you're planning on replacing your water heater and don't want to spend the time on the above methods to unclog your drain valve, moving your tank outside to drain is the best move for you. Here's what you need to do:

  • Disconnect the plumbing.
  • Disconnect the power source.
  • Use a hand truck to roll your water heater outside.
  • Carefully lay your water heater on it's side and to allow the water to drain from the top of the tank.

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