How To Install A Tankless Water Heater?

To install a tankless water heater, follow these steps: disconnect the old unit, mount the new heater to the wall, connect the water and gas lines, and plug in the electrical supply. This efficient and space-saving option provides instant hot water without the need for a storage tank.

Tankless water heaters are becoming increasingly popular due to their energy efficiency and long lifespan. By understanding the installation process, homeowners can save money on energy bills and enjoy a continuous supply of hot water.

How To Install A Tankless Water Heater?


Preparing For Installation

Tankless water heaters are a popular option for homeowners looking to upgrade their water heating system. Unlike traditional water heaters that store and constantly heat large volumes of water, tankless water heaters provide hot water on demand, resulting in energy savings and increased efficiency.

If you’re contemplating installing a tankless water heater in your home, there are a few things you need to consider before getting started. In this section, we’ll walk you through the steps of preparing for installation, including evaluating space availability and requirements, as well as determining the appropriate size and capacity for your household.

Evaluating The Space Availability And Requirements

Before you begin the installation process, it’s crucial to assess the space available in your home for a tankless water heater. Here are the key points to consider:

  • Location: Decide where you want to install the tankless water heater. It should be in close proximity to the gas, water, and electrical connections to minimize installation costs and ensure efficient operation.
  • Ventilation: Tankless water heaters require proper ventilation to remove exhaust gases. Ensure that you have enough space for venting, either through a direct venting system or a flue pipe.
  • Clearance: Check the manufacturer’s guidelines for clearances around the water heater. Tankless units usually require specific clearances from combustible materials to maintain safety standards.
  • Water supply: Evaluate the existing water supply lines in your home. You may need to install additional plumbing, such as dedicated hot and cold water lines, to accommodate the tankless water heater.

Determining The Appropriate Size And Capacity For Your Household

To ensure that your tankless water heater can meet the hot water demands of your household, it’s necessary to determine the appropriate size and capacity. Consider the following:

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  • Flow rate: Calculate your maximum hot water demand, which depends on the number of fixtures or appliances that will be using hot water simultaneously. Determine the required flow rate to accommodate all the hot water needs.
  • Temperature rise: Measure the difference between the desired hot water temperature and the temperature of the incoming cold water. This will help you determine the necessary heating capacity of the tankless water heater.
  • Gpm rating: Tankless water heaters are rated in gallons per minute (gpm) for the amount of hot water they can deliver. Select a unit with a gpm rating that meets or exceeds your maximum hot water demand.

By evaluating the space availability and requirements in your home and determining the appropriate size and capacity for your household, you’ll be well-prepared for the installation of a tankless water heater. In the next section, we’ll delve into the installation process itself, providing you with a step-by-step guide to ensure a successful installation.

Step-By-Step Installation Process

Ensuring All Necessary Tools And Materials Are Ready

Before beginning the tankless water heater installation process, it is crucial to gather all the necessary tools and materials. Here are the key points to remember:

  • Make sure you have the appropriate tools on hand, such as a wrench, pipe cutter, tape measure, drill, and screwdriver.
  • Check if you have the required materials, including the tankless water heater unit, venting components, gas or electrical supply connectors, water lines, and any additional accessories specified by the manufacturer.

Shutting Off The Water Supply And Disconnecting The Old Water Heater

To safely install a tankless water heater, you must first shut off the water supply and remove the old unit. Follow these steps:

  • Locate the main water shut-off valve and turn it off to stop the flow of water into the property.
  • Drain the old water heater by attaching a hose to the drain valve and directing the water to a suitable location.
  • Disconnect the water lines and electrical or gas connections from the old unit, ensuring you follow the appropriate safety measures.

Mounting The Tankless Water Heater And Connecting It To The Gas Line Or Electrical Supply

Proper mounting and connection are crucial to the tankless water heater’s functionality. Here’s what you should do:

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  • Determine the best location to install the tankless water heater, considering factors such as ventilation requirements, easy access, and proximity to the water and gas or electrical supply lines.
  • Attach the mounting brackets securely to the wall, ensuring they are level and stable.
  • Carefully mount the tankless water heater by following the manufacturer’s instructions.
  • Connect the unit to the gas line using approved connectors and fittings or wire it to the electrical supply adhering to the appropriate codes.

Installing The Necessary Venting System

A tankless water heater requires a venting system to expel combustion gases safely. Here’s what you need to know:

  • Choose the appropriate venting system based on the type of tankless water heater and the available installation space. It can be either direct vent, power vent, or indoor/outdoor models.
  • Follow the manufacturer’s specifications and guidelines for installing the venting system.
  • Ensure the vent pipes are correctly connected and securely fastened, allowing for proper airflow and exhaust.

Connecting The Water Lines And Ensuring Proper Connections

Properly connecting the water lines is essential for efficient and reliable operation of the tankless water heater. Pay attention to these points:

  • Determine the appropriate water supply pipes and connections based on the manufacturer’s recommendations and local plumbing codes.
  • Use the necessary fittings, valves, and adapters as required, ensuring a leak-free connection between the water lines and the tankless water heater.
  • Consider using flexible connectors or hoses to allow for easier installation and future maintenance if applicable.

Checking For Any Leaks And Performing A Pressure Test

After connecting the water lines, it is crucial to check for any leaks and perform a pressure test to ensure the system’s integrity. Follow these guidelines:

  • Slowly turn on the water supply and carefully inspect all connections for leaks. If any leaks are detected, tighten the fittings appropriately or replace faulty components.
  • Perform a pressure test by temporarily closing the water heater’s isolation valves and slowly increasing the water pressure to the manufacturer’s recommended level. Monitor the system for any signs of leaks or pressure drop, which may indicate an issue that needs to be addressed.
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Tuning And Adjusting The Water Temperature Settings

To optimize the tankless water heater’s performance, it is important to tune and adjust the water temperature settings. Keep these points in mind:

  • Consult the manufacturer’s instructions for accessing and adjusting the unit’s temperature controls.
  • Set the desired water temperature based on your preferences and local regulations.
  • Take note of any additional settings or features provided by the manufacturer to enhance efficiency or customize your hot water experience.

Activating And Testing The Tankless Water Heater

Once all installations and adjustments are complete, it’s time to activate and test the tankless water heater before regular use. Follow these steps:

  • Turn on the water supply and ensure there are no leaks or abnormalities in the system.
  • Gradually increase the hot water demand, allowing the tankless water heater to respond and provide the expected flow of hot water.
  • Monitor the system’s performance, paying attention to factors like water temperature, response time, and any signs of irregularities or malfunctions.

By following this step-by-step installation process, you can successfully install a tankless water heater and enjoy the benefits of energy-efficient and on-demand hot water. Remember to consult the manufacturer’s instructions and seek professional assistance if needed during any stage of the installation process.


Installing a tankless water heater is a practical investment that offers numerous benefits. Not only does it provide instant hot water on demand, but it also saves on energy costs and takes up less space than traditional water heaters. By following a few simple steps, you can successfully install a tankless water heater in your home.

Begin by shutting off the power and water supply, then remove the old water heater and prepare the installation area. Install the vent pipe, connect the water lines, and mount the new tankless water heater securely. Once everything is connected, turn on the power and water supply, and test the unit for any potential leaks.

Lastly, adjust the settings and enjoy your energy-efficient, space-saving tankless water heater. With a little know-how and attention to detail, you can easily complete this diy project and reap the long-term rewards.


I am a mechanical engineer and love doing research on different home and outdoor heating options. When I am not working, I love spending time with my family and friends. I also enjoy blogging about my findings and helping others to find the best heating options for their needs.