How To Replace A Residential Hot Water Heater


When we realize that we need a new water heater, it's usually at an inopportune moment. A long weekend with relatives over, the middle of a blizzard when a serviceman is nowhere to be found. Or in the middle of the night so we wake up to a cold shower.

Learning how to change a water heater can remove some of the fear that the unknown can lend to the situation. Changing a water heater is not a very complicated job and can be accomplished in most cases in a couple hours. Performing this job yourself can save hundreds of dollars on the installation.

Certain states and areas have plumbing codes that require this to be done by a licensed plumber so make sure you check the codes where you live to stay out of trouble.

Consider safety first at all times. This is an appliance that can hurt you. It is filled with water thatParts and tools won't scald you but it will hurt. It has either electricity running through it or gas connected to it or it's burning fuel oil. All of which take a bit of know how to work on safely.

It is recommended to let the heater cool and shut off power at the panel. Turn off gas at a positive shutoff and oil tanks should be mechanically isolated before servicing an oil fired unit. If you are unfamiliar with any of these types of apparatus then you should stop right here and hire a qualified serviceman.

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Draining Your Water Heater

Pump It Out Fast

Once we have found that a new water heater is needed we must locate a shutoff that will stop the flow of water into the tank. This is usually right at the heater on the cold pipe in. There are times however when the installer will neglect to add this valve. In this case sometimes the house main water must be shut down for the repair.

Make sure you have your replacement tank on hand as well as any fittings you may need to install the new tank. Tools should be ready and within reach. A dolly to move the tanks around is recommended. You will need a good garden hose and if you have a water transfer pump it can be hooked to the water heater drain and a hose connected to it to carry the water outside. After the water is shut off drain the tank with a hose.

After the tank is empty we are ready to disconnect the piping for the various elements. I usually start with the fuel on gas and oil heaters by disconnecting the lines that supply the fuel. Electrical units have been shut down in the electric panel and now I remove the wires at the heater.

Next I remove any flue piping from the unit. Place it all aside as we'll be using this to reinstall the new tank. Last but not least we must disconnect the water in and the water out lines. These lines are usually made from copper pipe and fittings but can be plastic as well. Get to know the type of pipe you have and the fittings it will take to hook up the new tank.

Pipe and fittings are available at the local hardware store as well as home improvement stores. Parts can also be bought on line at and other retailers and they'll ship them right to your house.

After everything is all apart we can remove the heater and place the new one in the spot. Connect the hard piped copper lines first. This may be done with soldered pipe and fittings or compression fittings with nuts and Ferrel's that are tightened with wrenches and squeeze the pipe for a water seal. However your tank is hooked up it's the water lines that should be done first. This way the tank can be filled and tested for leaks before you hook up everything else.

Next connect the fuel lines back to the new heater. or attach the wiring in the case of an electric water heater. Your final connections will be to replace any flue piping back into the chimney or whatever vent your unit uses.

After the piping is all back together, we can start the unit and check for leaks. The job is done and a bunch of money has been saved. One last part of this job will be to vent any air out at the faucets to keep water from spraying everywhere. Open faucets slowly until a solid stream of water is achieved.

Set the temperature on the water heater control to mid range and then give it a day or two, so you'll know where it must go from there. It is recommended to run the heater on the lowest setting that will give you enough hot water. This will maximize the life of the unit.


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