Step-by-Step Guide: How to Install an Electric Water Heater

Discover how to install an electric water heater with our detailed guide that takes you through every critical step of the process.

From selecting the right location for your new unit to understanding the intricacies of safely removing an old heater, this guide is your go-to resource.

We also tackle the timely question of whether heater installation is a feasible DIY project or if it necessitates the expertise of a professional.

With comprehensive instructions and expert tips, you'll be equipped to make informed decisions, ensuring a successful and safe installation in your home.

How to install an electric water heater: Things to consider

How does an electric water heater work?

Electric water heaterElectric water heater

An electric water heater is a straightforward device used to heat potable water. Cold water from the home's plumbing system enters the storage tank, where it is heated by electric elements.

The cold water enters the tank through an inlet tube (marked with a blue ring), commonly known as a dip tube, and exits through the hot water outlet (marked with a red ring). Inside the tank, one or two electric resistance elements heat the water, which is then delivered to showers or other fixtures at the point of use.

Each heating element is regulated by a thermostat, which activates the element when the water temperature inside the tank falls below the preset level.

Common problems leading to the replacement of an old water heater

If your old electric water heater isn't functioning properly—manifesting issues like insufficient or no hot water, extremely low recovery and efficiency—it's time to consult our troubleshooting guide. This guide is designed to help you diagnose and fix common problems, potentially saving you from an expensive purchase.

Begin by checking the basics: ensure there's no tripped circuit breaker or reset button issue, and verify if the unit is receiving power. However, be mindful that these symptoms might indicate a more serious underlying issue.

Nonetheless, if your old heater is exhibiting more severe problems, such as leaking, rusty water, tank deformation, or persistently low performance even after attempted repairs, it may be prudent to consider investing in a new electric water heater.

Additional considerations for your installation project

If your older heating system didn’t include the expansion tank and pressure relief valve, now is the time to install it.

Expansion tanks are used in closed water heating loops to reduce the water pressure buildup when it gets higher than usual, protecting the heater’s elements.

Pressure relief valves are also recommended in homes where the water pressure inside the plumbing varies. The recommended pressure ranges from 50 to 60 PSI, while everything above 80 PSI requires you to install a valve, therefore avoiding potential problems.

Standard electric water heaters with two heating elements operate on 240V, which requires breakers and a wire gauge set by the manufacturer (usually a 30-amp circuit breaker and 10-2 wire with the ground). Make sure that the correct voltage is supplied to the heater, as stated on the rating plate.

Recommended fuse size chart

Watts 120V 208V 240V
600 10A 5A 5A
750 10A 5A 5A
1000 15A 10A 10A
1250 15A 10A 10A
1500 20A 10A 10A
2000   25A 15A
2500   30A 15A
3000   35A 20A
3500   25A 20A
3800   25A 25A
4000   25A 25A
4500   30A 25A
5000   35A 30A
5500   35A 35A
6000   40A 35A

Note: Always follow the manufacturers’ manual for instructions. Check local building codes and get all the necessary permits.

If you are not sure how to install an electric water heater or have problems during the replacement, contact a professional plumber to help you.

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How to install an electric water heater

Choosing the best location for your electric unit

When installing an electric water heater in a new house, it's crucial to choose the location thoughtfully.

Ideally, the water heater should be situated near the point of use, as well as close to electrical and plumbing connections. It's important to place it in an area where it won't cause damage or pose a risk to people in case of leaks or malfunctions.

It's advisable to avoid storing flammable materials in the same room as the heater for safety reasons.

Although electric heaters are designed for indoor use, they still need protection from freezing in colder environments. This can be achieved using insulation blanket and pipe sleeves.

Ensure that the unit is installed upright on the floor. All controls and the drain valve should be easily accessible for maintenance, repair, and servicing purposes.

Required tools

  • Multimeter (voltage detector)
  • Set of screwdrivers
  • Adjustable wrench
  • Pliers
  • Tubing cutter (if using copper pipes)
  • Torch (if using copper pipes)
  • Soldering flux and solder wire (if using copper pipes)
  • Wires and wire nuts
  • Garden hose
  • Bucket
  • Teflon tape (pipe dope)
  • Earthquake straps (where required)

Detailed step-by-step installation instructions

  • Safety first: Turn OFF the power - Ensure the power is off at the electric panel box.
  • Locate the junction box - Find it on top of the heater.
  • Confirm power disconnection - Use a multimeter to test the wires attached to the heater, ensuring the power is indeed off.
  • Disconnect electrical supply - Carefully remove the conduit from the tank.
  • Pressure and temperature reduction - Open a nearby faucet to alleviate pressure and reduce the temperature of the water inside the tank.
  • Water supply shutdown - Turn off the water supply to the tank using the nearby shut-off valve.
  • Prepare for draining - Find the drain valve at the bottom of the heater.
  • Drain the tank - Connect a garden hose to the drain valve, leading the other end to a floor drain or outside. If draining is difficult, the valve may be clogged with sediment. Refer to our article on sediment removal.
  • Accelerate draining - Open a faucet or the T&P valve to expedite the process.
  • T&P Valve preparation - Locate the T&P valve on the heater's top and remove the discharge pipe.
  • Disconnect water supply pipes - Detach both cold and hot water supply pipes from the top of the unit.
  • Remove the old tank - Carefully use a dolly to transport the old tank away.
  • Install a drain pan or elevate - Place a new drain pan, or set up concrete blocks for elevation, to protect against floods and facilitate future draining.
  • Set the new heater - Position the new water heater in the drain pan or on the platform.
  • Connect the T&P valve discharge pipe - Ensure it allows unobstructed flow to the drain, ending about 6 inches from the floor. Alternatively, use a bucket.
  • Install inlet and outlet pipes - Attach the new cold water inlet (blue ring) and hot water outlet (red ring). For convenience, consider using flexible steel pipes, SharkBite Push-to-Connect fittings, or PEX tubing.
  • Seal connections - Apply Teflon tape on threads where necessary, optionally combined with pipe dope. Use dielectric fittings to prevent corrosion.
  • Reactivate water supply - Turn on the cold water supply.
  • Check for leaks - Open the hot water tap and inspect all connections for any signs of leakage.
  • Fill the tank - Once you observe a steady stream of water, let it run for a few minutes to remove air from the system.
  • Reconnect electrical wiring - Remove the junction box cover and connect the wires using wire nuts.
  • Power On - Turn the power back on at the breaker box.
  • Heating time - Heating the water can take several hours, depending on the heater's specifications.
  • Set desired temperature - Adjust the thermostat to your preferred setting, typically around 120-125°F to prevent scalding. The thermostats are behind the access plates and insulation.
  • Important reminder - Never turn on the heater before the tank is full to avoid dry firing, which can damage the heating element.

Note: A water heater tank must be full of water because if you turn the heater on too early and if the heating element is not submerged into the water, you might get a dry firing which will destroy the component.

Related: How to install a gas water heater


As indicated above, installing an electric water heater is not an overly complex task, particularly for DIY enthusiasts who possess the right tools. However, it does require basic to intermediate knowledge of electrical and plumbing work.

It's important to remember that new electric heaters typically have a lifespan of 10-15 years. Therefore, whether your heater is old or has started to malfunction, it's advisable to attempt a repair first, or at least have a plumber assess it. Only if it's deemed beyond repair should you consider purchasing a new one.

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