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How to Install a Tankless Water Heater: A Step-by-step Guide

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  • Post last modified:August 27, 2023

If you’re considering a tankless water heater for your home, it’s important to know how to install it properly for optimal performance. With this step-by-step guide, you can confidently tackle the installation process and enjoy the many benefits of a tankless water heater.

Before you start the installation process, it’s important to gather all the necessary tools and materials, assess your home’s needs, and understand the cost associated with the installation. Additionally, safety considerations must be taken into account to ensure a safe installation process.

In this guide, we will break down the tankless water heater installation process into easy-to-follow steps and provide tips to help you achieve a successful installation. From assessing your home’s needs to testing and troubleshooting after installation, we’ve got you covered.

Key Takeaways:

  • Proper installation is key to achieving optimal performance from your tankless water heater.
  • Gathering necessary tools and materials, assessing your home’s needs, and understanding the cost associated with installation are important steps to take before beginning the installation process.
  • Safety should be a top priority during the installation process.

Understanding Tankless Water Heaters

As a professional journalist, I understand the importance of providing readers with accurate information. That’s why it’s essential to understand what a tankless water heater is and how it differs from traditional water heaters.

A tankless water heater, also known as an on-demand water heater, heats water only when it’s needed. Unlike traditional water heaters that keep a constant supply of heated water in a tank, tankless water heaters have no storage tank and instead, heat water through a heat exchanger as it flows through the unit.

The tankless water heater installation process is different from installing a traditional water heater, and there are a few benefits to consider.

  • Energy Efficiency: Because tankless water heaters heat water only when needed, they’re more energy-efficient than traditional water heaters, which means lower utility bills.
  • Space-Saving: Tankless water heaters are smaller in size compared to traditional water heaters, which saves space in your home. They can be installed in small spaces such as closets, attics, or even outside.
  • Longevity: Tankless water heaters have a longer lifespan than traditional water heaters, which means fewer replacements and cost savings in the long run.

Now that we understand the basics of tankless water heaters let’s move on to assessing your home’s needs in the following section.

tankless water heater installation process

Assessing Your Home’s Needs

Before installing a tankless water heater, it is important to assess your home’s needs to determine the right model that will work efficiently and effectively. Consider factors such as the size of your home, the number of bathrooms and fixtures, and your typical water usage to determine the right size and capacity.

Additionally, you should consider the required electrical and gas specifications needed to install the unit. Large tankless water heaters may require additional electrical circuitry or gas lines to be installed, so it’s essential to check your home’s electrical and gas system requirements before purchasing a unit.

Also, make sure to determine the appropriate location for the unit. Most tankless water heaters are mounted on the wall, so it’s essential to ensure that there is enough space and proper ventilation for the unit to operate safely. Keep in mind that some models may require outdoor installation and may not be suitable for certain climates or environments.

Overall, assessing your home’s needs and requirements is crucial to ensure that the installation process goes smoothly and to prevent any damage or safety hazards.

tankless water heater installation requirements

Gathering the Necessary Tools and Materials

Before beginning the installation process, it is important to gather all the necessary tools and materials. This will ensure a smooth and efficient installation. Here is a checklist of items you will need:

  • Tankless water heater unit
  • Gas line (if applicable)
  • Exhaust pipe and fittings
  • Water supply lines and fittings
  • Plumbing tape
  • Adjustable wrench
  • Pipe cutter or hacksaw
  • Drill and drill bits
  • Screwdriver set
  • Level
  • Measuring tape
  • Wire cutters/strippers
  • Electric voltage tester

Having all the required tools and materials in advance will make the installation process smooth and easy. Failing to have the necessary tools and materials may lead to delays and inconveniences. Prepare yourself in advance with everything you need, so you don’t have to run back and forth to the hardware store or take unnecessary breaks.

tankless water heater installation checklist

Make sure you have everything you need before beginning the installation process to ensure a smooth and efficient installation.

Preparing for Installation

Before installing your tankless water heater, it’s important to make sure you have all the necessary tools and materials. Here’s a checklist to help you prepare:

  • Adjustable wrenches
  • Pipe cutter or hacksaw
  • Screwdrivers
  • Teflon tape
  • Gas leak detector
  • Electric drill and bits
  • Level
  • Tankless water heater unit
  • Water and gas lines (if applicable)
  • Vent pipe and fittings
  • Flashing
  • Wall thimble
  • Stainless steel hose connectors

Once you have everything you need, it’s time to begin preparing for the installation process. The first step is to shut off the utilities to your existing water heater. This may involve turning off the gas or electricity and shutting off the water supply. You should also take the time to drain the existing water heater if applicable.

Next, you’ll want to remove your old water heater unit. This typically involves disconnecting the water and gas lines, as well as removing any mounting hardware or brackets. It’s important to follow the manufacturer’s instructions for removing your specific unit to avoid damaging your home or the unit itself.

Once you’ve removed the old unit, it’s time to begin installing your new tankless water heater. Make sure to carefully follow the manufacturer’s instructions to ensure a safe and successful installation.

tankless water heater installation process

Note: Always make sure to turn off the utilities and follow the manufacturer’s instructions for a safe and successful installation.

Installing the Tankless Water Heater

With all the necessary preparations out of the way, it’s now time to install the tankless water heater. Follow these step-by-step instructions for a successful installation:

  1. Mount the unit: Choose a location for the unit that is close to the main water line and electrical or gas supply. Use the mounting template provided by the manufacturer to secure the unit to the wall or other surface. The unit should be level to ensure proper operation.
  2. Connect the water lines: Install isolation valves on the cold water inlet and hot water outlet. Connect the valves to the unit using appropriate plumbing fittings. Be sure to use Teflon tape or thread sealant on the threads to prevent leaks.
  3. Connect the gas and electrical lines: If your tankless water heater is powered by gas, install a gas shut-off valve and connect the gas supply line to the unit. If it’s electric, connect the unit to the electrical panel using appropriate wiring and breakers. Follow the instructions provided by the manufacturer to ensure proper connection and grounding.
  4. Ensure proper ventilation: Tankless water heaters require proper ventilation to function safely and efficiently. Install a vent pipe to the outside, following local codes and regulations. Use appropriate materials and fittings, and ensure that the pipe is properly sized and sloped.
  5. Test the unit: Turn on the unit and let it run for several minutes to ensure proper operation. Check for leaks and ensure that hot water is flowing from the taps. Adjust the temperature setting according to the manufacturer’s instructions.
  6. Finalize the installation: Secure all connections and install any covers or panels provided by the manufacturer. Clean up the work area and dispose of any debris or old parts.

Remember that these are general instructions and the specific steps may vary depending on the unit and installation requirements. Always follow the manufacturer’s instructions and local codes and regulations to ensure a safe and proper installation.

tankless water heater installation process

Testing and Troubleshooting

After completing the installation of your tankless water heater, it is important to test the unit thoroughly before use. This will help identify any issues or leaks that may need to be addressed. Here are the steps to follow:

  1. Check for leaks: Visually inspect the unit and connections for any leaks. Turn on the hot water and check for leaks again. If you notice any leaks, turn off the water supply and gas (if applicable) and tighten the connections or contact a professional plumber.
  2. Adjust temperature settings: Follow the manufacturer’s instructions to adjust the temperature settings to your liking.
  3. Test the unit: Turn on the hot water and check the flow and temperature. Make sure the unit is not making any strange noises or emitting any foul odors. If you notice any issues, consult the troubleshooting guide in the user manual or contact the manufacturer for assistance.
  4. Address common issues: Some common issues that may arise after installation include air in the pipes, insufficient water flow, and error codes. Refer to the user manual for information on how to address these issues or contact the manufacturer for assistance.

It is important to address any issues or concerns before regular use of your tankless water heater. This will ensure that the unit operates efficiently and safely for years to come.

tankless water heater installation testing

Safety Considerations

When it comes to installing a tankless water heater, safety should always be a top priority. Following these tips will help ensure a safe installation process:

  • Make sure the unit meets all local and state codes and regulations.
  • Ensure that the installation area has proper ventilation to prevent the buildup of carbon monoxide.
  • Turn off the electrical and gas supply before beginning the installation process.
  • Use caution when handling pipes and connections to prevent burns and other injuries.
  • If the installation requires electrical work, turn off power to the area and seek the assistance of a licensed electrician if needed.
  • For gas installations, use a licensed gas fitter to make gas and venting connections.
  • Never attempt to modify a gas line yourself or use flexible gas connectors where they are not allowed by code.

By following these guidelines, you can ensure that your tankless water heater is installed safely and properly.

tankless water heater installation requirements

Post-Installation Maintenance

Once your tankless water heater has been successfully installed, it’s important to perform regular maintenance to ensure it continues to run efficiently.

Tip: Set a reminder on your calendar to check your water heater every six months to a year.

The following are some tips on how to maintain your tankless water heater:

Task Frequency
Check for leaks Monthly
Clean the air intake filter Monthly
Descale the unit Annually
Schedule professional maintenance checks Annually

Tip: Consult your owner’s manual for specific maintenance instructions.

Checking for leaks should be done monthly to prevent water damage. Inspect all connections and make sure they’re tight. If you notice any leaks, contact a professional plumber for repairs.

Cleaning the air intake filter is also crucial to the unit’s performance. A dirty filter can lead to a decrease in efficiency. To clean the filter, simply remove it and rinse it with water. Let it dry completely before replacing it.

Descaling the unit is necessary if you have hard water. Over time, mineral buildup can lead to decreased efficiency and even damage the unit. Descaling involves flushing the unit with a descaling solution. It’s important to follow the instructions in your owner’s manual to avoid damaging the unit.

Finally, scheduling professional maintenance checks can help catch any potential issues before they become larger, more expensive problems. A professional plumber can also ensure your unit is running at peak efficiency and make any necessary adjustments.

tankless water heater installation tips

Understanding the Cost of Installation

When considering the installation of a tankless water heater, it is important to understand the associated costs. While the initial cost of a tankless water heater may be higher than that of a traditional water heater, the long-term savings may outweigh the upfront expense.

The average cost of a tankless water heater installation ranges from $1,500 to $3,500. This includes the cost of the unit, installation fees, and any necessary modifications to your home’s electrical or plumbing systems. However, the cost may vary depending on the size and type of the unit and the complexity of the installation.

One major benefit of a tankless water heater is its energy efficiency. These units are designed to only heat water when it is needed, rather than continuously heating a large tank of water. This can result in significant savings on your monthly energy bills.

tankless water heater installation cost

It is important to note that while a tankless water heater may provide long-term savings, it may not always be the most cost-effective option for every household. It is important to assess your individual needs and budget before making a decision.

Additionally, it is important to consider any potential additional expenses that may arise during the installation process, such as the need for new ventilation systems or gas lines. It is recommended to obtain multiple quotes from licensed professionals before proceeding with the installation.


Installing a tankless water heater can seem like a daunting task, but with this step-by-step guide, it can be a manageable DIY project. By following the instructions and tips outlined in this article, you can successfully install a tankless water heater and enjoy the benefits it provides.

Remember to assess your home’s needs, gather the necessary tools and materials, and take safety considerations into account. Be sure to complete post-installation maintenance tasks to keep your unit in tip-top shape and save money on energy bills in the long run.

By understanding the cost factors associated with tankless water heater installation, you can make an informed decision on whether it’s the right choice for you. I hope this article has given you the knowledge and confidence to tackle this DIY project and enjoy the benefits of a tankless water heater.

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