How to Install an Electric Water Heater

In an electric water heater, a heating element heats the water. This is different from a gas-fired water heater, in which a gas-fired burner heats the water. The heating element is controlled by a thermostat located on the outside of the hot water heater.
To replace a failing electric hot water heater or install a new one, you need a dedicated electric wire and a cold-water supply line.

Safety Tip: Before installation, turn off the water. Make sure power to the water heater is turned off at the main circuit breaker. Remove any fuses.

• When figuring out how to install an electric water heater, check the old tank's labels for size and energy specifications before buying a new one. Water heaters manufactured after 2015 meet new energy code requirements. They require electric water heaters with a tank to have more insulation in them. Newer water heaters have gotten bigger in width and height compared to models built prior to 2015 of the same capacity from the same manufacturer.
• Measure the area where the old water heater fits. If your current water heater was manufactured before 2015, check the new model's specs to ensure it will fit in the current space.
• For greater energy efficiency, consider a tankless electric water heater, which heats water on-demand rather than storing it in a tank. With a point-of-use electric water heater, water is heated closer to the sink, tub or appliance where it will be used, which helps eliminate waste. They can be placed in a bathroom or kitchen. But you should consult a plumber when installing a hot water heater of this type.
• Many communities have specific requirements in their local plumbing codes for residential water heaters. When installing a water heater, make sure it will comply with installation code requirements for your location and type of water heater.

When installing an electric water heater, certain tools are required. These include:

• Adjustable pipe or socket wrenches
• Pipe and tubing cutter
• Pipe-fitting brush
• Wire cutter
• Screwdriver
• Non-contact voltage tester
• Carpenter’s level
• Soldering iron

You will also need the following materials when installing a water heater:

• Electric water heater
• Thermal expansion tank
• Flexible water supply connectors
• Copper piping and plumbing fittings, including elbow joints
• Pipe adapters
• Valves, including drain, temperature and pressure relief (rated for your heater)
• Plumber’s (thread seal) tape
• Wire connectors
• Solder
• Emery cloth
• Shims
• Hand truck
• Pencil
• Garden hose
• Safety glasses and other personal protective equipment (PPE)
• Paper towel, old rags or towels
• Buckets or water heater drain pans

• Before installing a hot water heater, turn off the breaker that controls the water heater. Use a non-contact voltage tester to ensure that power is off to the water heater.
• Turn on the nearest hot water faucet and allow it to run until the water runs cool. This will allow you to safely drain the unit without worrying about hot water. Keep this faucet open as it will allow the tank to drain faster.
• Once the water runs cool, turn off the water supply to the water heater at the closest shut-off valve.
• Attach a garden hose to the drain valve and empty the tank either into buckets, a floor drain, a sink in the basement or an appropriate place outside. If you choose to drain the tank while the water in it is still hot, use extreme caution when doing so.

Next, you’ll need to detach the electric supply and water lines from the old water heater.

• After confirming that the electric supply is off, disconnect the wire from the thermostat on the water heater using a screwdriver.
• If your existing electric water heater setup is already equipped with dielectric unions at the top of the tank, disconnect the cold water supply and hot water supply at the union using two adjustable wrenches or pipe wrenches. If the piping has been soldered into place, use a tubing cutter to cut the pipe. Clean the pipe with Emery cloth before cutting the pipe. This will make it easier to prep for the solder connection later.
• Using an adjustable wrench or pipe wrench, remove the overflow pipe and pressure release valve from the old hot water heater. You will reinstall it on the new unit.
• Remove the old water heater. Older water heaters fill with sediment over time, so prepare for it to be heavier than a new one. You may need a helper and an appliance dolly.
• Dispose of your old water heater. Check with your local sanitation or recycling company for information on how to discard it in accordance with local ordinance. When using a professional installer, make sure they remove the old water heater as part of their service.
• Clean the floor where the old water heater stood.

Now you’re ready to begin installing an electric water heater with a tank. If replacing an old model or installing a hot water heater from scratch, ensure that it will have at least 6 inches of clearance on all sides for adequate ventilation.

• Align the water heater to ensure easy access to the thermostat controls. Follow the manufacturer’s guidelines and local code requirements to ensure the location meets minimal clearances for combustible materials.
• Use a carpenter’s level and plastic shims to level the water heater as needed.
• Now install the pressure relieve valve (also called a T & P valve). If your new hot water heater did not come with one, install a new one. Don’t reuse the one from your old tank.
• Wrap the threads several times with Teflon tape, then thread the valve onto the tank.
• Using an adjustable wrench or pipe wrench, continue tightening the valve until it points directly to the floor.
• Next, thread the copper discharge pipe from the old water heater onto the new relief valve using Teflon tape on the threads.

Tip: Stand the water heater in a drain pan that will catch water and run a line to a nearby floor drain in case it ever leaks.

Next, attach the heat trap fittings and water line connections. Heat trap fittings improve your water heater’s efficiency by not allowing any hot water to leave the tank, or cold water to enter it when it’s not in use. Connect the plumbing supply lines to the water heater according to manufacturer’s instructions and local code requirements. Solid copper pipe or flexible copper supply lines are common.

• Wrap the water heater heat trap fitting pipe threads using Teflon tape. Many of these fittings are directional, so find the arrows that show the correct direction for installation. If installed wrong, water will not flow properly or at all.
• Attach the blue-coded fitting to the cold-water inlet with the arrow facing into the water heater.
• Attach the red fitting to the hot water outlet with the arrow pointing away from the water heater.
• Tighten using a pipe wrench or adjustable pliers.
• Measure and cut the water line connections to length as needed.
• When sweating the remaining copper sections, it’s best to dry-fit everything first. Sweat any threaded copper fitting first, then let them cool before installing them onto the heat trap fittings. Once you have the pieces in place, pull the parts apart and clean the inside of each joint and the end of each section of pipe. Use Emery cloth and/or a pipe fitting brush to do this.
• Apply flux to the fittings and pipe, assemble, and then solder using a propane torch.
• Reconnect the water line.

Tip: If you must have soldered fittings, we recommend professional installation. You can also opt to use water heater supply lines in lieu of making sweat connections. Some of these options contain push-to-connect fittings or compression fittings.

Once the connections are made, fill the hot water heater.

• Open the shut-off valve on the cold-water supply to allow water into the tank.
• Open one or more faucets on the home’s highest floor and run the water until it flows steadily from the faucets. A steady flow of water indicates that the tank is full.
• If the water pressure has changed, remove the aerator on the faucets and remove any sediment that may have entered the line.
• When completely filled, close the faucets and check for leaks around the new connections at the hot water heater.
• To check for leaks, you can run your finger around the fittings, use a paper towel or a dry rag.
• If any water is present, drain the tank and reconnect the fittings.

Now that the tank is full, it’s time to figure out how to wire an electric water heater. You’ll need to connect the electrical wire to the water heater.

You don’t want to do this before the tank is full as this could cause the heating elements to burn out.

• Connect the electrical supply according to the manufacturer’s instructions.
• Be sure to connect the bare copper or ground wire to the ground screw to ensure that the water heater is properly grounded.
• Replace the electrical access plate.
• Remove the thermostat access plate and then pull back any insulation to expose the thermostat.
• Use a screwdriver to change the thermostat temperature setting in 10-degree increments. The recommended temperature is 120-degrees.
• When the electrical connections are made and all access plates are reinstalled, restore power by turning the circuit breaker back on.