How to Wire a Tankless Water Heater in 2022 – Complete Guide

How to Wire a Tankless Water Heater in 2022 is a crucial question as no tankless water heater can operate without electricity. It is because each tankless water heater has an internal PC circuit that controls the unit. You can see a part of it in the form of the display screen on the tankless water heater. Knowing certain things about wiring or having a complete understanding of it can help you diagnose the problems and install the new tankless water heater.

However, it is by no means we encourage you always to do this. Because there are several things, you need to consider that can make or break your investment in a tankless water heater. So, to avoid any problems caused by neglect, make sure to read the entire article. We all know that it costs a considerable sum to install a tankless water heater which most of us want to save. This is when knowing how to wire a tankless water heater might come in handy. But, most tankless water heater manufacturers advise that you hire a licensed professional to do this for you. It is because a professional knows the specifications and functionalities of installing a tankless water heater perfectly.

Before we tell you about the wiring of a tankless water heater, we want to give an overview of a tankless water heater. It is for those interested in a tankless water heater and wants to buy and install it themselves. Tankless water heaters are also known as on-demand water heaters and sometimes also refer to as instant water heaters. Unlike a traditional water heater, they don’t hold water in a tank or heat it regularly. But what they do is that they heat water at the moment whenever you need it. As they only heat for a limited time, hence energy consumption is also limited to that timeframe. This way, you can observe a lot of savings due to energy efficiency.

Furthermore, you need to evaluate some features of tankless water before you decide on which one to buy.  A tankless water heater needs to be assessed on the following features:

What type of fuel does it use ( Natural Gas, Propane, or Electricity)

Indoor or outdoor unit

Initial + installation cost

Energy efficiency or Energy Factor

Flow Rate or Maximum Water Heating Capacity

It is critical to comprehend these elements in order to make informed decisions. Returning to our subject, you should be familiar with the various types of tankless water heaters. It is essential as the procedure of wiring differ for each type to a certain extent.

Tankless water heater types:

Tankless water heaters are classified into two kinds.

Gas operated

Electric operated

Gas operated water heaters:

These units operate on the combustion of natural gas or propane to power the unit. Thus, you need to deal with the harmful gases that arise from the combustion of gases. Hence, such a water heater needs proper vents installed to exhaust these gases outside your house. Vents are not required if such a unit is installed outdoor.

Since gas tankless water heaters are primarily powered by natural gas or propane, that is why they only need limited electricity, which is used to operate the PC circuit or Display screen. Hence, a 120-Volt circuit is sufficient for its operations.

Electric operated water heaters:

An electric tankless water heater uses electricity instead of gas or propane to power its operations. Hence, they do not need a vent to exhaust outside the house. Although, being an electric tankless unit, they have higher requirements for the electrical circuit in your household. Electric water heaters require 240-volt power. In addition, they are best for small households due to their inability to match high demands (providing hot water to 4-5 faucets at the same time).

Wiring an electric tankless water heater is covered in detail in this article. A gas tankless water heater needs further installation of gas pipelines and Vents, etc., which have no relation to the wiring process.

Requirements for wiring a tankless water heater:

These conditions must be met before a tankless water heater can be installed.

Checking Warranty:

Some of the tankless providers have a clause in their warranty for licensed professional installation. In case you install the unit yourselves, it can result in the tankless warranty being void. So, an effort to save money can result in a more significant loss.

Permit/License:

In some states of the US, it is required that you get to have a permit/license before installing these water heaters in your household. In addition, the government departments inspect and check out the criteria fulfillment in terms of requirements, specifications, and working of these water heaters.

Electrical circuit requirement:

It would be best to have a 240 Volt Circuit for mounting a Tankless Water Heater at your home.

Tools Required:

Now, coming onto the point of what tools you require to wire your tankless water heater. The list of the essential tools is here for your convenience.

Drill machine

Drill bits for drill machine

Head screwdriver

Adjustable Crescent wrench

Flathead screwdriver

Needle nose pliers

Measuring tape

Pipe cutters

Pencil

Skill required:

Having some tools does not mean that you can do something like an expert. You need sufficient skills to match the tools to get the work done. For the wiring of a tankless water heater, you need these skills. You must have intermediate level or Advanced level knowledge of electricity and how to handle electric appliances.  Additionally, it would be best if you are a Licensed Electrician or hire an expert to do this for problem-free installations.

How to Wire a Tankless Water Heater:

Some of the things to be mindful of when installing a tankless water heater are:

Always take pictures at each step before you make changes to anything so that you can restore the previous setting if needed.

Ideally, a water heater should be situated close to a source of hot water that you use frequently. You’ll have hot water much faster this way.

Remember to install the tankless electric water heater vertically with the electrical and the water lines facing down.

In addition, it should be at a sufficiently open place where you can do maintenance. Typically, a place where you can access the electrical sockets and the sewer drain.

A general rule of thumb is to avoid places where

Where there is a great chance of liquid splashing on your water heater.

Where a sufficient chance of temperatures dropping to below freezing.

Where there is excessive moisture or excessive humidity.

Removing your Old Water Heater:

Tank water heaters are extremely simple in their installation as well as their replacement by removal. It does need much science or much skills. It becomes even easier if you do so in a sequence manner. To complete the process, simply follow the steps below.

1.  Disconnecting the power:

No matter which electrical appliance you are dealing with, never mess with it when its power is on. You can get shocked and could be life-threatening. So, the first step is to disconnect the power to the appliance.  You can do this by shutting the breakers to break the power flow. Recheck it using a tester or a voltage meter to ensure there is no voltage in the unit.  In case it is a gas water heater, shut off the gas supply.

2. Pressure valve and Drain valve

Release the pressure valve in the tank but be sure to wear your safety equipment when you do so. You should wear your glove and safety glasses as due to high pressure; the hot water may sprinkle on you. Be very careful.  After relieving the pressure in the tank water heater, drain the water in the tank. Also, make sure that water supply valves are closed so that freshwater doesn’t keep on refilling.

3. Remove the junction box cover:

A junction box is usually present on the top of the tank water heater. You can see wires going into a space covered with metal plates. The metal plates can be removed using a screwdriver or with a drill machine. You can get to the wire connection point with the water heater by removing the lid. However, you may need a needle nose plier to disconnect the connections.

4. Unwound the pipes:

Use an adjustable crescent wrench to unwind the pipes connections and remove the tank water heater.

How to Install a Tankless Water Heater:

  1. Location selection and mounting

The first stage in the installation process is to decide where the tankless unit will be installed.  Make certain you’ve considered all of the above-mentioned tankless considerations. Once the site has been selected, mount the unit on the wall. As most tankless water heaters are made to be mounted on the wall, you can easily do it by following the manual. However, the process may differ based on make and model. Tankless water heaters come with screws and anchors that you can drill into the wall, and the tankless unit is mounted on it for support.

2. Bring the pipes (water and gas) to the tankless water heater

Before you do so, make sure that all supply lines are closed before bringing the pipe to the tankless water heater, as new circumcisions need to be made to direct these new pipes from the existing pipelines.

It is also the time of opportunity. As at this moment, you can make a lot of installations that can prolong the lifespan of your tankless water heater. Some of these installations are a must to have, like insulation valves and the pressure relief valve. At the same time, other helpful installations include a reducing valve (which you can install if the water pressure coming to your home exceed 150 psi). And a water softener system (which you can install if your area has hard water. It can help reduce the scale and sediment buildup in the tankless unit).

3. Attaching the pipes

Once pipes have reached the tankless unit, the method of attachment varies based on the pipes you are using. Standard fitting using a wrench or combination of junk and cement is enough. Moreover, make sure to use Teflon tape or plumbers tape between pipes connection points to ensure no leakage. Teflon tape is a great way to seal any gap between the fittings.  One thing to remember is to never solder the pipes permanently. As you may have to un-attach them for maintenance or any other purpose.

4. Wiring the tankless water heater

To access the wiring, you need to remove the front panel of the tankless water heater. You’ll see that the unit contains a substantial amount of cable. Don’t be alarmed; you won’t be dealing with many of them. Every wire inside the unit has already been sorted out.  All you need to do is the wiring connections between the circuit and the tankless unit. This necessitates the consideration of two factors. Which size wire should you use, and how many breakers should be used. You can find the best instructions on how to do this by following your instruction manual with the tankless water heater. While some other things to take note of are:

An installation manual for the unit you have will specify the amount of dedicated circuitry required.

If you require more room in the panel for the circuit breaker, the make and model of the panel may allow you to use a quad circuit breaker.

Assume that your electrical panel allows you to use twin or tandem breakers. In that case, you can replace the existing full-size circuit breakers with twin circuit breakers, which will free up space for a new circuit. This only applies if your electrical panel offers twin or tandem breakers.

Once done, double-check the connections and place the front panel in its place. Open the water supply and allow the water to circulate through the unit, and check for any leakage. Once everything is okay, turn on the power and enjoy the tankless experience.

Estimated time required:

A licensed professional takes around one to five hours to install a tankless water heater. However, a newbie will take much longer to do this. As the time taken varies based on experience and familiarity with work.

Precautions:

You need to ensure that all electrical wire connections with or within the tankless water heater are adequately secured. Similarly, you also need to keep the wirings clean instead of messily joining them. Which can make it difficult to pinpoint which wire is for what when you came across any problems in the future.  

It is best if you follow the proper electrical and plumbing codes and get permission from the authorities. Getting permission from the authorities is essential as you need to know whether your local transformer can support the circuit upgrade. In case it couldn’t support the upgrade and fails to work. The authorities may impose the fee of getting the new transformer on you.

Hence, it is recommended that the homeowners do no work on electrical circuits and panels unless they are licensed electricians.

Frequently Asked Questions

What are the electrical requirements for a tankless water heater?

Electric tankless water is a high-power device that needs a minimum amperage of 120. In comparison, most of the homes have an electrical circuit of 200 AMP. This means that the old electrical circuits cannot meet the requirement of the electric tankless water heater. Hence, you need to upgrade it.

Do tankless water heaters need special wiring?

You need to use 8-gauge wires for your tankless water heater, which are the upgraded form of the wires used in your electrical circuit. The electric wire used for your previous water heater may not cut in supplying sufficient electricity to the tankless unit.

How many wires do you need for a tankless water heater?

The number of wires that a tankless water heater needs depends on its number of heating elements. Similarly, you also need to install 40-50 Amp breakers for each wire to ensure that your tankless unit lasts for the most extended duration.

Conclusion

Knowing how to wire a tankless water heater in 2022 is helpful regardless of whether you want to install the tankless water heater or diagnose any problem faced by the tankless water heater. Saving money is a good policy. But it is not always valid. That’s why you need to check whether your tankless provider allows D-I-Y installation or requires a licensed professional’s installations. Some of the tankless manufacturers add the clause of professional fittings in their warranty. This means that although cheaper, a D-I-Y installation can cost you a much more significant sum in the form of a warranty being void.


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