Replacing an Electric Water Heater
Fast and Easy

Replacing an electric water heater is a straightforward DIY home project. This mini-guide will provide you with the basics not only to replace but install any electric model.

Electric water heaters are simple devices that can be easily installed in your home. If you are skillful, have some HVAC knowledge, the right tools, and with the help of this guide, you don't have to call an expensive plumber to repair or replace a unit or any of its parts - you can do it.

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Electric water heater from AO SmithElectric water heater from AO Smith

This article will help you understand electric heaters better, so if the unit fails, you will know how to substitute it with a new and better one, a model that will work efficiently, perform well, last longer and save you money.

If there is no hot water or a water heater is not performing well, no need to start replacing a water heater immediately - first double-check all other options you have.

Instead, you might need to do some repairs; replace a part, fix a leak, or drain and flush to remove the buildup sediments for efficient work.

Depending on the heater's manufacturer, usage of a heater, quality of water, and other factors, the tank's life can be shorter than expected. Moreover, it can surprise you.

Most of today's electric hot water heaters can last over 10 years with regular maintenance, but sooner or later, the unit will either leak because of the rusty tank or malfunctioning tank's elements.

Replacing a water heater unit is not complicated; it requires you to disconnect and hook up water lines and disconnect/connect some electrical wires.

Check out how an electric water heater works and what are the main components. The most challenging job is handling the heavy tank. For this job, get someone to help you, and for moving a heavy load, use a dolly cart.

Instructions about replacing electric water heaters are made for homeowners with basic knowledge about plumbing, gas, and electrical work, and we will lead you through 8 easy steps on how to do it correctly.

If you are the owner of the gas model, see an article how to replace a gas water tank heater in 10 easy steps.

Tools needed

  • Pipe wrench
  • Tongue and groove pliers
  • Hacksaw or pipe cutter
  • Unions, fittings, or flex connectors
  • Teflon tape or joint compound
  • Thin wire
  • Soldering torch
  • Wire brush and sandpaper
  • Appliance dolly
  • Garden hose
  • Level
  • Screwdriver
  • Voltage meter or 240-Volt Neon Test Light

How to replace a water heater in 8 easy steps

Replacing and installing a new electric hot water heater is much simpler than replacing the old gas unit; there is no delicate work on the flue vents and gas line.

Important: Take precautions when working on the electrical devices, as the water heaters usually operate at 240 Volts. For this home project, you need some plumbing skills and tools.

So, the 8-step-by-step guide explains how to:

Step 1. Drain the water from a storage tank

Before you do any work on the electric water heater, make sure to turn OFF the electricity on the electrical breaker.

Open the hot water tap in the bathroom or kitchen above the unit (highest tap unit) and on the tap close to the unit (lowest point).

The goal is to drain the hot water out and cool down the tank's hot water.

Find the main water valve that supplies water to your home and turn it OFF. You can do the same thing on the shutoff valve that supplies water to the heater, usually located nearby the unit.

Take the garden hose and attach it to the heater's drain valve located at the bottom. Open the drain valve and let all the water from the tank out to a floor drain or outside. You can use this guide to get more details on how to drain a water heater.

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Step 2. Disconnect the electrical wires

Double-check if the power is OFF on the electrical panel (visually) and on the thermostat (using the voltmeter).

There is an access panel and thermostat behind the lower part of the electrical water heater. Once you remove the cover, check if there is current running by using a voltage meter or 240-volt neon test light.

If there is no power, proceed to the next step, to unplug the wires.

At the top of the unit, remove the cover that leads to the heater's junction box, find two electrical wires, and disconnect them from the main electrical supply (usually connected with the two-wire nuts). 

You can also check the wires with the multimeter.

Don't forget to mark them accordingly so you will know where exactly to reconnect them when replacing a water heater.

Step 3. Disconnect the plumbing lines

With the unit drained and disconnected from the electrical supply, proceed to the next step and disconnect the unit from the home plumbing.

Make sure to remember or mark where the incoming cold water line and outgoing hot water supply are. If this electric unit uses a rigid galvanized pipe, simply open unions close to the unit, using the set of adjustable wrenches.

If using a solid copper pipe, cut the pipe close to the shutoff valve. Be sure to have the straight cut, and remove all the particles, burrs, and sharp edges. Prepare the copper pipe for soldering.

If you need a plumber to make the changes on the pipes and connect the heater, contact this company.

Step 4. Move the old unit out

Make some room for the new electric hot water heater by moving the old unit out. As said, the unit is heavy, especially if it was affected by the sediment buildup, so use wisely all the help needed, including the dolly cart.

If you need help to choose the right electric water heater, there is some excellent information (a guide actually) about choosing the right tank unit, money-saving tips, reviews of different brands and manufacturers.

Step 5. Position a new heater

If you were happy with the performance of the old unit, hot water production, recovery rate, efficiency, try to match the features when buying a new one. If the characteristics are the same, installation is easy. Bring the new unit in using a dolly cart. Line up the unit to the existing plumbing, with the drain pan underneath - it helps when the unit is leaking.

Keep in mind that the electric water heaters are indoor units and should be sheltered from freezing temperatures.

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Step 6. Connect the electric heater with the water line

First, check the local codes and manufacturer's manual, what type of water line can be used. If it is a solid copper pipe, use it. Solder the pipe and copper fitting to the heater on one side and plumbing on the other. You can also use compression fittings, which makes the work even faster and easier.

If you have to work with the galvanized pipes, use a wrench and union to make the connection.

Plastic pipes and plastic fitting joined with the pipe compound are easier to use and don't require any heat source, just a hacksaw for cutting.

The easiest way is using the flexible copper and stainless steel pipes with the pipe nuts at the end. It is recommended in areas at risk for earthquakes.

To reduce the risk of corrosion when connecting pipes made of two different metals, always use dielectric fittings.

Also, install a new temperature and pressure relief valve (TPR), rated for your model (and pressure) and with the adequate drain pipe.

Step 7. Connect the water heater to the electrical supply

Run the electrical cable through the clamp where the heater's junction box is and connect these two wires to the heater's wire connectors. Attach the ground wire to the ground screw. Tighten the screw on the clamp so it can hold the cable in the right spot.

Step 8. Before you start a water heater

Set the thermostat to the desired temperature; 120 F or 50 C is recommended hot water temperature, press the reset button and put the access cover back.

Turn the water valve ON and open the nearest hot faucet so water can run for some time. This will remove any air pockets left, so it won't be trapped in the tank. When the water flows freely, close the tap.

Replacing a water heater as a simple home project is now completed, and your electrical unit is ready for the test shower.

Note: When replacing any water heater type, always follow the manufacturer's instructions, warnings, local codes, and of course, safety first. Make sure the tank is full of water before turning it ON because the heating element can burn out prematurely (actually in a matter of seconds).

If the project is time-consuming, unsafe, hard to complete, you don't have the right tools, or something gets wrong... hire a professional.

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