How to Install an Electric Tankless Water Heater

(Last Updated On: March 31, 2020)

The days of using old bulky water heaters with large tanks are over. Sleek, space-saving tankless water heaters are becoming the norm these days, especially in upscale housing. The reason is pretty obvious, just in the word “tankless”. Installing an electric tankless water heater is a lot less hassle as it doesn’t have a huge tank and it doesn’t use up valuable space in your home.

Just like tank water heaters, a tankless water heater also has two types—electric and gas. Today, we’ll discuss the electric tankless water heater. (For recommendations on the best electric tankless water heaters, check out this article.)We’ll describe its benefits and the installation process in depth. If you’re tired of looking at that old bulky water heater or want to make some extra room, let’s talk about how to upgrade!

Can a layman install a tankless water heater?

To install a tankless water heater, there are quite a few steps, such as mounting the unit and connecting the gas line (obviously not needed with an electric water heater) and water line to it. If you’ve never installed a tankless water heater, but think it’s something you want to try, give this article a read and you can determine whether it’s within your wheelhouse. If you’re questioning your abilities on some of the steps, we would definitely recommend using a professional.

How much does it cost to install an electric tankless water heater?

Installing a tankless water heater can be quite costly if compared to installing an ordinary water heater. The costs are dependent on many factors, such as the region in which you live, how outdated your house plumbing and electrical wiring is, whether you’re installing a high capacity vs. low capacity water heater, etc. A plumber may charge as little as a few hundred dollars up to $3,000 ($50-$150/hr). Additionally, an electrician may be required, which could cost several hundred or thousands of dollars more ($50-$100/hr).

Do I need a permit to install a tankless water heater?

For safety reasons, a permit is required to install a tankless water heater in your home. This inspection ensures the water heater has been installed properly and it won’t create any hazard for the building or the neighbors around your home.

Advantages of Electric Tankless Water Heaters

When compared to conventional water heaters, an electric tankless water heater is pretty superior. Some of the main benefits are as follows:

  • Size: They are tiny compared to tank water heaters. They are simply mounted on a wall, in a garage, or even in a cupboard so they don’t cover up any floor area or take up an entire closet.
  • Appearance: They simply look sleek, cleaner, and more modern. Seeing a tankless water in a home will likely please potential home buyers.
  • Economical: They save a lot of energy because of their higher efficiency. The US department of energy states that conventional water heaters account for up to 30% of average family energy bills. Using an electric tankless water heater reduces this cost by up to 50%.
  • Durability: They are more durable than an ordinary water heater. Tankless water heaters can last 20 years or longer.

Disadvantages of Electric Tankless Water Heaters

There aren’t many, but the main drawback is pretty clear:

  • The most obvious drawback of a tankless water heater is the upfront cost of setting it up. You may need both an electrician to set up good wiring and a plumber to install it and possibly build necessary piping.
  • If you live in a region with hard water, you’ll have to connect a water softener to it which is also an additional cost.

Cost to Service an Electric Tankless Water Heater

One thing to keep in mind is that every water heater needs servicing. In the case of tankless water heaters you will also need to keep it clean and flush out the sediment from it. The average cost of servicing ranges from $100 to $800. You can save this cost if you can flush sediment out of water heater by yourself. To learn how, check out this article.


Steps to Install an Electric Tankless Water Heater

Electric tankless water heaters generally needs a higher voltage power supply, a special stainless steel flue or large diameter exhaust system. Make sure you have them before starting to plug it in.

Use Special Union connectors

To improve the flow of water and stay ready for future maintenance, you should use special union connector sets to connect water pipes or exhaust pipes to your water heater. This makes it easy to maintain in the future.

Turn off the Incoming Water Line

As you’ll need to connect water lines to your tankless heater, you must stop the flow of water before working. Before unplugging the water line from your old water heater and connecting it to your new one, turn off the incoming water line of your house.

Unplug the Heat source of the Old Water Heater

After you turn off the water supply, you need to unplug the heat source of the old water heater so that you don’t burn yourself with hot water. With an electric water heater, need to unplug the heater from the socket and also turn the current off to that area with at your breaker box.

Drain the Old Water Heater

Turn on some of the water faucets around your house to hot and let them run until the water is cool. Before you remove the old water heater you’ll need to drain it completely. These two steps are imperative as you don’t want the weight of the water to make it more difficult to move the water heater and you certainly don’t want to risk water leaking everywhere or hot water scalding you. You can drain it using the drain valve on it connected to a garden hose. Run the garden hose to the outside of the building so the water can run off safely. Make sure the end of the hose is lower than the level of the drain on the heater so the water will flow.

Remove the Old Water Heater

Now, remove the old water heater from the place it was kept. The big tank water heaters can be very heavy, so using a dolly or a friend will help. Empty the space to make room for the new tankless water heater. You probably will want to give the space a good cleaning, too.

Take out the Tankless Heater and Mount it on Wall

Now take out the new tankless electric water heater and mount it on the wall using support. Make sure that you have balanced the weight properly on the support using the support system provided by the company. Use the manual to properly fit it in.

Connect the Cold Water Line

First connect a union connector to the inlet of the water heater and then plug in the pipe of the cold water supply to that connector. Once you’re done, ensure the fitting is perfect and tight so there is no chance of a water leak.

Connect the Hot Water Pipe on the Outlet

Now again connect a union connector to the outlet then connect the pipe that will carry hot water to the house with the union connector of the outlet.

Connect the Exhaust or Flue

Heating the water inside the on-demand tankless water heater will produce a lot of heat and gas inside the heater. You will have to let it out from the system. For that, you will have to connect a flue or exhaust to it. This will take away the gas from it. Add this flue with a pipe that will pass out the gas into air. Connect this pipe that will allow it out of the house

Plug in the Heater

After you have connected all the pipes properly, connect the plug that will provide power to the tankless water heater. You should connect it to a socket that can provide at least 120amps to the water heater.

Give it a Test Run

Now, open the main cold water source and switch on the water heater. Then wait for few minutes and turn on any faucet in your house. Check that is the water hot. If it is hot then your work is done. If not, then recheck the fitting and make sure current is entering the electric water heater.



An electric tankless water heater can be quite an upgrade from an old tank water heater. It will reduce your energy bills, free up space from your home, and look more aesthetically appealing. It heats up water only when you need it, so it’s more environmentally friendly and efficient. The latest water heaters have cool safety features so that if there is a power failure it will automatically turn off the heating process of the water. It may have a high up front cost, but will save you money in the long run and perhaps add a bit to the resale value of your home.


Tankless Reviews was created with the goal of helping people to understand the benefits and practical knowledge related to tankless water heaters. After purchasing my very first tankless heater years back, I realised that other people needed to hear about the incredible money-saving ability of this household item, and wanted to share my lessons with you!