Replacing a Water Heater
8 Fast and Easy Steps
(updated 2017)

Replacing a water heater powered by the electricity is a very simple DIY home project. This mini guide will provide you with basics not only to replace but install any electric model. The electric water heaters are simple devices and if you are skillful, have some HVAC knowledge, have the right tools, and with the help of this guide, you don't have to call an expensive plumber or professional to repair or replace a unit or any of its parts - you can do it.

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.

What we suggest here is not to start replacing a water heater immediately, but to double check all other options you have.

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

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

Most of today's electric hot water heaters can last over 10 years with the 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 at all, 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 difficult job is handling the heavy tank. For this job get someone to help you, and for moving use a dolly cart.

Replacing electric water heaters instructions are made for people like you and we will lead you through 8 easy steps how to do it correctly. If you are the owner of the gas model, see 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 trying to substitute 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 are usually operating at 240 Volts. For this home project, you need basic plumbing skills and tools.

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

No hot water?
Get help now!
Finding the right contractor is fast, easy and free!

Get Free Plumbing Quotes!

Step 1. Drain the water from the storage tank

Before any work has been done 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 hot water out and cool down the tank's hot water.

Find the main water valve that supplies water to your home and turns it OFF. You can do the same thing on the shut-off 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.

Step 2. Disconnect the electrical wires

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

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

If there is no power proceed to the next step, to disconnect 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 is using a rigid galvanized pipe, simply open unions close to the unit, using the set of adjustable wrenches.

If using a copper solid 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 a help to choose the right electric water heater, there are some good 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.

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 the 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 source of the heat, 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.

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

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

Step 7. Connect water heater with 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, and 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 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.

emergency plumber
› Replacing a water heater

Today on Sale!


water heaters