Written by: Gene Fitzgerald // Last Updated: Mar 7, 2023
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Buying an electric tankless water heater is only the first step. The unit must also be properly installed in your home.
This job calls for good plumbing and electrical skills, and might better be done by a licensed professional (even required in some areas).
However, if you prefer to install your new water heater DIY-style, be prepared to spend a couple of hours in order to finish the whole setup.
Want to learn all the details? The following guide explains how to install an electric tankless water heater step by step.
Key Takeaways
Before getting started, check if your home can handle the amp draw of an electric tankless water heater. Ask your electrician or check your electrical breaker box
How to Install:
What are the requirements to install an electric tankless water heater?
Not every home is suited for a whole house electric tankless water heater. This is because the amp draw of such a system is simply too high. For example:
The Stiebel Eltron Tempra 36 Plus requires 3 separate dedicated 50A double pole breakers and a recommended main service of at least 300A. To put this into perspective, the average home has a total capacity of 200A.
This could mean that you have to upgrade your old electrical service panel with bigger wires and bigger breakers, or you have to run a completely new one entailing a couple of thousand dollars worth of electrical work.
FYI: The Stiebel Eltron Tempra 36 Plus can provide 5.45 gallons per minute at 59 °F feed water and 105 °F output water temperature.
Stiebel Eltron Tempra 36 Plus – Available on amazon.com
The Tempra 24 Plus which is somewhat smaller still requires 2x 50A double pole breakers and 150A main service.
A point-of-use (POU) electric tankless water heater should not be a problem in terms of amperage requirements. Also, while most require 240V power, some very small POU units can run on 120V.
How to determine the current size of your home’s electrical service? Check the electrical breaker box that can usually be found outside the house. You could also look for a label in your electrical panel. Another option would be to ask your electrician.
Most electric tankless water heaters can work at a pressure range between 30 and 150 psi. If the incoming water pressure is above 150 psi a pressure reducing valve must be installed upstream of the heater.
As a homeowner you are usually allowed to install a water heater yourself. However, in most states you must still pull a permit to have it inspected for safety. This also goes for replacing an old water heater.
A plumbing inspector will come to your place and look at the installation to make sure that the work was done properly.
The first step is to find an appropriate wall to mount the water heater to. For a whole house water heater, it makes sense to place it close to where most hot water is being used. This will allow you to get warm or hot water faster when you open an outlet (doesn’t matter if you use a recirculation pump; more info below). At the same time, you have to have access to the main cold water line.
For point of use systems, you want to place them as close to the point of usage as possible so the water reaches the outlet in a timely manner.
The good news is that electric water heaters don’t need venting. And because we don’t have a storage tank we can choose a location where a tank-based unit may not fit – think small bathroom or even under sinks.
Just keep in mind that most electric tankless water heaters must be installed vertically with the power and water supply connections pointing downward. Also, there must be minimum clearance for servicing.
Generally speaking, you should avoid locations where
Equally problematic are excessive moisture and humidity.
Failure to comply with this will likely void your product warranty.
Tools and supplies you need to successfully install your new electric tankless water heater may include the following:
You haven’t purchased a system yet? Definitely check out our electric tankless water heaters reviews to find the best one! You can learn how to properly size an electric tankless water heater here.
In addition you might need tools and supplies for soldering.
Before you get started, please note that this step-by-step installation guide is only meant as an example. The required steps to set up your specific water heater may vary. Thus, make sure that you read the entire product manual.
What’s more, improper installation will likely void the warranty, may decrease system lifespan, and could result in serious personal injury or death. So if you don’t know what you are doing, do yourself a favor and hire a licensed electrician and plumber to do the install for you. The job is too dangerous and not worth the risk just to save a few hundred bucks.
On a side note, with some manufacturers their systems must be installed by a licensed contractor or else the warranty will void automatically.
And lastly, if you have any questions regarding the installation call tech support.
Disclaimer: It is recommended that this job is done by a licensed professional. Furthermore, the installation must comply with all national, state and local electrical and plumbing codes.
Prefer video? You might find this helpful:
Lastly, some additional comments:
You can learn more about how much electric tankless water heaters cost here.
Low-hanging hot water pipes coming from the water heater should be insulated to protect children from burns.
Even with a tankless a.k.a. instantaneous water heater, you won’t have instant hot water whenever you open the kitchen faucet or another outlet. This is because the hot water sitting in the pipes will eventually cool down if you don’t use it.
Fortunately, there is a solution to this: A recirculation pump. A recirculation pump circulates the cooled-off water back to the heater to heat it once more. This has a couple of advantages:
How does a recirculation pump work? Most use a sensor to measure water temperature near the heater or at a certain fixture. The pump activates as soon as the water temp has dropped below a certain threshold.
How can the water circle back? There are two options:
Now, you might be thinking: “A recirculation pump in combination with a tankless water heater would cause a huge waste of energy due to frequent pumping and re-heating.” And you were right, if you wouldn’t make use of some type of smart control.
A smart control – this can be a timer, a button, a motion sensor, a remote… – ensures that the pump activates at certain times of the day only, let’s say right before you wake up in the morning.
Laing Recirculation Pump with Timer & Thermostat – Available on amazon.com
Another aspect to consider is pump volume. Too small of a pump with too little flow would fail to activate the water heater.
If you are interested to learn more, you can check out this pump that has a built-in timer + thermostat or this model that can be fired up with the help of a remote.
If you have any questions about how to install a tankless electric water heater please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
Information provided on BOS is for educational purposes only. The products and services we review may not be right for your individual circumstances.
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I am wanting to install for the shower only, do I wire it on the same line as the (electric jets) tub?
ReplySorry Catrina, it’s not possible to provide a useful answer without further details.
ReplyYour information is very helpful. Thank you for writing this!
Reply