Back to blogs

Your Guide to DIY Tankless Water Heater Installation

Are you tired of running out of hot water mid-shower? Do you want to save energy and reduce your utility bills? If so, it may be time to consider installing a tankless water heater in your home. While this may seem like a daunting task, with our expert guidance, you can confidently tackle this DIY project and enjoy the benefits of a continuous supply of hot water.

Key Takeaways

  • Installing a tankless water heater can provide you with a continuous supply of hot water and can save you money on energy bills.
  • With our comprehensive guide, you can successfully install a tankless water heater as a DIY project.
  • Assessing your water heater needs, gathering necessary tools and materials, and performing proper preparation are crucial steps for a smooth installation process.
  • Proper venting, gas, water, and electrical connections are essential for safe and efficient operation of your tankless water heater.
  • Regular maintenance is necessary to prolong the lifespan and efficiency of your tankless water heater.

Understanding Tankless Water Heaters

When it comes to choosing a water heater, traditional tank water heaters are no longer the only option. Tankless water heaters have gained popularity in recent years, and for good reason. Here are some of the benefits of choosing a tankless water heater:

  • Energy Savings: Tankless water heaters are designed to be more energy-efficient than traditional tank water heaters, as they only heat the water when you need it. This means that you can enjoy hot water on demand while using less energy and saving money on your utility bills.
  • Endless Hot Water: With a tankless water heater, you can enjoy a continuous flow of hot water, as it heats the water as it passes through the unit. This eliminates the need to wait for a tank to fill up and heat the water, ensuring you always have access to hot water when you need it.
  • Space-Saving Design: Tankless water heaters are typically much smaller than traditional tank water heaters, making them a great option for those with limited space. They can be mounted on a wall or installed in a compact location, providing you with more room for storage or other appliances.
  • Long Lasting: Tankless water heaters have a longer lifespan than traditional tank water heaters, as they don't have to work as hard to heat the water. This means that you can enjoy hot water for many years to come, without the need for frequent replacement.

Now that you understand the benefits of a tankless water heater, it's time to consider which model is best for you. Here are some popular models based on customer reviews:

Model Max Flow Rate Fuel Type Price Rheem Performance Platinum 9.5 GPM Natural Gas $1,149 EcoSmart ECO 27 6.5 GPM Electric $499 Takagi T-H3-DV-N 10 GPM Natural Gas $1,234

These models are just a few examples of the wide range of tankless water heaters available. When selecting a model, consider your household's hot water needs, the size of your home, and your budget.

Assessing Your Water Heater Needs

Before installing a tankless water heater, you must assess your current water heater's capacity and determine if a replacement is necessary. This step is crucial because different households have different hot water needs, and choosing the wrong water heater could result in insufficient amounts of hot water or unnecessarily high energy bills.

The first thing to consider is the size of your current water heater. The size of the water heater is measured in gallons, and it is usually indicated on the unit. To determine if a water heater replacement is necessary, you should compare the size of your current water heater with the hot water demand in your household. A household with high hot water demand may require a larger water heater compared to a household with low hot water demand.

If your current water heater is too small for your household's hot water needs, you may need to replace it with a larger one or consider a tankless water heater. Tankless water heaters are available in different sizes and can provide hot water on demand, making them an efficient solution for households with high hot water demand.

On the other hand, if your current water heater is too large for your household's needs, you may also consider a tankless water heater or a smaller conventional water heater. A large water heater may result in higher energy bills due to unnecessary heating of excess water.

Aside from choosing the right size of water heater, you should also consider the age and condition of your current water heater. If your water heater is more than 10 years old and has frequent breakdowns or leaks, it may be time for a replacement.

Ultimately, determining your water heater needs is an essential step in ensuring that your household has a constant supply of hot water while maintaining energy efficiency and reasonable costs.

Gathering the Necessary Tools and Materials

Before starting a DIY water heater installation project, it's essential to have all the necessary tools and materials on hand. We've compiled a comprehensive checklist to ensure that you have everything you need:

Tools Materials Adjustable wrench Tankless water heater Pipe cutter Gas pipe (if applicable) Plumber's tape Water pressure gauge Screwdriver set PVC pipe (if applicable) Drill and bits Water filters (if applicable) Level Compression fittings Gas leak detector solution Flux Torch Sandpaper

All of these tools and materials can be purchased at most home improvement stores or online retailers. Having all of these items on hand before beginning the installation can save you time and frustration during the process.

If you don't have experience with DIY projects or don't have access to the necessary tools, it's important to hire a professional plumber to install your tankless water heater. Attempting to install the unit without the proper tools or experience can lead to expensive repairs or even pose a safety risk.

With these tools and materials at your disposal, you will be well-equipped to take on your tankless water heater installation with confidence.

Preparing for Installation

Proper preparation is crucial for a successful tankless water heater installation. Before beginning, turn off the water supply and gas or electricity to the existing water heater. Drain the tank and disconnect all plumbing and electrical connections. Any necessary maintenance must be performed on the water heater before removal.

Once the existing water heater is removed, measure the space where the tankless water heater will be installed and ensure it meets the unit's clearance requirements. Check for any damage or corrosion to the pipes and replace or repair as necessary.

Make sure you have all the necessary tools and materials listed in the previous section. We recommend laying them out in an organized manner, making it easy to access everything during the installation process.

Tools Materials Adjustable Wrench Tankless Water Heater Gas Pipe Thread Sealant Gas Connector Tubing Cutter Water Pipe Connectors Pipe Wrench Teflon Tape Screwdriver Pressure Relief Valve Plumbing Tape Condensate Drain Hose Level Anchor Screws Drill Reciprocating Saw

For additional safety, we recommend having a fire extinguisher and carbon monoxide detector nearby during the installation process.

Finally, we recommend reading the manufacturer's instructions thoroughly before beginning the installation. Familiarize yourself with the unit's features and functions and review any safety warnings or precautions.

With the proper preparation and tools, you'll be ready to move onto the next step: choosing the right location for your tankless water heater.

Choosing the Right Location for Tankless Water Heater Installation

When choosing the location for your tankless water heater, there are several factors that you need to consider to ensure that it functions efficiently and safely.

Proximity to Gas and Electrical Connections

A tankless water heater requires a gas or electrical connection to operate. When selecting a location, you need to make sure that it is close to the connections to avoid excessive piping or wiring and additional expenses.

Size of the Unit

The size of your tankless water heater will depend on your household's hot water needs. A larger unit may require more space and located in an area where it can accommodate the unit's size and ventilation requirements.

Ventilation Requirements

Proper ventilation is crucial for the safe operation of your tankless water heater. It is recommended that it be installed in a well-ventilated area to prevent the buildup of harmful gases. Ensure that the venting requirements are met as outlined in the manufacturer's instructions.

Access for Future Maintenance

Most homeowners don't think about future maintenance when selecting the location for their tankless water heater. It is important to select a location that provides easy access to the unit for future maintenance.

Environmental Considerations

Lastly, consider the environmental factors such as earthquakes, floods, or high-wind areas that could affect the installation location of your tankless water heater. Choose a location that is safe from any natural disasters and provides a secure and stable area for the unit.

By following these guidelines, you can ensure that your tankless water heater is installed in the ideal location that meets your household's hot water needs safely and efficiently.

Installing the Tankless Water Heater

Now that you have gathered all the necessary tools and materials and have prepared the installation area, it's time to begin installing your tankless water heater. Follow these steps:

  1. Mount the water heater on the wall using the mounting template provided by the manufacturer, making sure it is level.
  2. Connect the hot and cold water supply lines, ensuring the proper direction of flow. Use appropriate fittings and connectors to avoid leaks.
  3. Install the pressure relief valve on the hot water outlet.
  4. Connect the gas supply line (if applicable) using a flexible connector approved for use with tankless water heaters.
  5. Connect the exhaust pipe to the vent hood, using appropriate screws or clamps.
  6. Connect the unit to the power supply (if electric), making sure all wires are properly grounded and a dedicated circuit breaker is installed.
  7. Install any required controller or remote to the designated location.

Before turning on your new tankless water heater, make sure all connections are tight and there are no leaks. To test the unit, turn on the hot water faucet and wait for the heater to ignite. Check for proper temperature and flow. If there are any issues, refer to the troubleshooting section below or contact a professional plumber for assistance.

Venting and Exhaust Considerations

Proper venting and exhaust are crucial for the safe and efficient operation of your tankless water heater. The type of venting required depends on the unit's size and fuel type. It's important to follow the manufacturer's specifications and local building codes to ensure safe installation.

Venting Options

There are two primary venting options for tankless water heaters:

  1. Direct Vent: This option requires a dedicated vent pipe that goes directly outside through a wall or roof. It uses a sealed combustion system that draws air from outside and exhausts through a separate pipe. Direct venting is ideal for smaller units and tight spaces.
  2. Power Vent: This option uses a fan to push exhaust gases through a vent pipe that can be installed vertically or horizontally. It's ideal for larger units and where venting through a wall or roof is not possible.

Installation Process

When installing the venting system, you should consider the following:

  • The vent pipe must be the correct size and type for the unit and fuel type.
  • The vent pipe should be as short and straight as possible, with minimal turns and bends to avoid backdrafting.
  • The vent pipe must be secured and supported to prevent sagging or detachment.
  • The vent pipe must have proper clearances from combustible materials, such as walls and ceilings.

It's highly recommended to have a professional installer or plumber handle the venting installation to ensure safety and compliance.

Connecting Gas Supply

Connecting the gas supply line is a crucial step in installing a gas-powered tankless water heater. It requires careful attention to detail to ensure a safe and effective connection.


  • Gas line
  • Gas line fitting
  • Gas pipe thread sealant
  • Wrench
  • Leak detection solution


  1. Turn off the main gas supply valve before beginning any work.
  2. Wrap the gas line fitting with gas pipe thread sealant to ensure a tight seal.
  3. Attach the gas supply line to the gas line fitting with a wrench, taking care not to over-tighten.
  4. Open the main gas supply valve and check for leaks using a leak detection solution. Apply the solution to the gas line fitting and watch for bubbles. If bubbles appear, turn off the main gas supply valve immediately and tighten the fitting until the bubbles stop.
  5. Once the connection is secure and there are no leaks, perform a final leak test before proceeding with the installation.

Connecting the gas supply line requires specialized expertise. If you're not comfortable working with gas lines, consider hiring a professional plumber or gas fitter to handle this step.

Connecting Water Supply

Now that you have located the ideal location and mounted your tankless water heater, the next step is connecting the water supply lines. This requires attaching the hot and cold water supply lines and any necessary additional components.

The first step is to connect the hot and cold water supply lines to the appropriate valves on the tankless water heater. The hot water supply line should be connected to the hot water outlet valve, and the cold water supply line should be connected to the cold water inlet valve. Be sure to tighten the connections with a wrench properly.

Pressure Relief Valves

It's vital to install pressure relief or safety valves on your tankless water heater. These valves keep the water pressure from reaching dangerous levels to prevent damage to the unit and ensure your safety. Placing a T&P valve on the hot water outlet pipe and cold water inlet pipe, or installing an expansion tank as per the manufacturer's instructions, is recommended.

Additional Components

Some models of tankless water heaters may require additional components to function correctly. These components may include check valves, a hot water recirculation pump, or a de-scaling system. Before starting the installation, make sure you read the manufacturer's instructions to find out if any additional components are required and include them in your installation plan.

After connecting the water supply lines and additional components, check all connections for any leaks. Turn on the cold water supply at the main valve and then turn on the hot water tap at a nearby sink or bathtub. Perform a visual inspection of all supply lines and connections while the water runs to make sure there are no leaks. Tighten any connections as needed.

With this step complete, you're almost ready to start using your new tankless water heater. However, before you do, it's essential to make electrical connections and ensure proper grounding. We will cover this in the next section.

11. Electrical Connections and Power Supply

Connecting the electrical wiring is a critical step in the installation process. One small mistake can lead to a malfunctioning unit or, worse, a safety hazard. Follow our instructions to ensure a safe and efficient connection.

Before starting, make sure you have the necessary tools, including wire strippers, electrical tape, and a voltage meter.

First, shut off the power supply to the unit and then verify the voltage with your voltage meter. Next, remove the cover plate to access the electrical wiring. Ensure that the wires are correctly labeled, and strip about 1/2 inch of insulation from each wire.

If you're using a plug-in cord, attach the wires to the corresponding terminals on the plug and plug it into the appropriate outlet. If you're using a hard-wired power supply, connect the wires to the corresponding electrical terminals on the unit. Always double-check that the wires are secure and in the correct locations.

Finally, cover the electrical connections with electrical tape and replace the cover plate. Turn on the power supply and test the unit to ensure it's functioning correctly.

Testing and Troubleshooting

After completing the installation of your tankless water heater, testing and troubleshooting is the final step to ensure that your unit is fully functional. Follow our comprehensive checklist to ensure your tankless water heater is operating safely and efficiently.

  1. Check for leaks: Prior to turning on your new tankless water heater, perform a visual inspection of all water and gas connections to ensure there are no leaks.
  2. Check the water flow: Turn on the hot water faucet and check if the water is flowing steadily and without interruption. If the water flow is not optimal, check the water pressure and make necessary adjustments.
  3. Check the temperature: After the water begins to flow, test the temperature. Adjust the temperature settings according to your preference or the manufacturer's instructions.
  4. Test the safety features: Test the pressure relief valve and ensure that it is functioning properly. The pressure releif valve helps to prevent the tankless water heater from overheating and becoming too pressurized.
  5. Review the manual: Before using your tankless water heater, review the manufacturer's instructions thoroughly to ensure you have a clear understanding of the unit's features and functions.

Troubleshooting Common Issues

Here are some common issues that may arise with your tankless water heater:

Issue Possible Cause Solution No Hot Water Power outage, Gas interruption, insufficient gas pressure Check the power source and gas supply. Call a professional if necessary Water Temperature Fluctuation Dirty water filter, air in the lines, incorrectly set temperature Clean the water filter, purge the air from the lines, adjust the temperature Strange Noises Mineral buildup, loose parts, incorrect installation Clean the unit, tighten any loose parts, call a professional if necessary

By following our guide and troubleshooting checklist, you can confidently install and maintain your tankless water heater to ensure it performs optimally and meets your household's hot water needs.

Maintenance and Care

Regular maintenance is vital to ensure that your tankless water heater is functioning at optimal capacity. By performing routine maintenance, you can extend the lifespan of the unit and prevent the need for costly repairs. Here are some essential maintenance tips:

Flush the System

Over time, mineral deposits and sediment can build up in your system, reducing its efficiency and potentially causing damage. We recommend flushing your tankless water heater once a year to remove any accumulated debris. You can do this by following the manufacturer's instructions or contacting a professional plumber.

Clean the Filter

The filter on your tankless water heater prevents debris from entering and damaging the system. It's essential to clean or replace the filter every six months to ensure optimal performance. Refer to the manufacturer's guidelines for specific instructions.

Check for Leaks

Periodically check your tankless water heater for leaks. If you notice any, contact a professional plumber immediately. Delaying repairs can lead to more significant issues and costly repairs.

Check the Pressure Relief Valve

The pressure relief valve on your tankless water heater is a safety feature that releases excess pressure to avoid damage to the unit. You should periodically test the valve by lifting the lever and letting it snap back into place. If the valve doesn't release water or doesn't snap back into place, it may need to be replaced.

Inspect the Ventilation System

Proper ventilation is essential to ensure your tankless water heater operates safely and efficiently. Check the ventilation system periodically to ensure it's free of debris and operating correctly. If you notice any issues, contact a professional plumber.

Professional Maintenance

We recommend having your tankless water heater professionally serviced every 3-5 years. A trained plumber can ensure the system is functioning correctly, identify any potential problems, and perform necessary maintenance tasks.

Following these maintenance tips will help you keep your tankless water heater in optimal condition and extend its lifespan. By performing routine checks and cleaning, you can avoid costly repairs and enjoy continuous hot water for years to come.

Calculating the Cost and Savings

When considering installing a tankless water heater, it's essential to understand the associated costs and potential savings. In this section, we'll break down the expenses involved and help you determine if it's a worthwhile investment for your household.

Initial Cost

The upfront cost of a tankless water heater is higher than a traditional water heater. On average, a tankless water heater costs between $800 and $1,500, while a traditional water heater costs between $300 and $600.

However, it's important to note that a tankless water heater has a longer lifespan than a traditional water heater, lasting up to 20 years with proper maintenance.

Installation Cost

The installation cost of a tankless water heater is higher due to the additional electrical or gas line installation and venting requirements. The installation cost can range from $1,000 to $3,000, depending on the complexity of the project and your geographic location.

Energy Savings

The primary advantage of a tankless water heater is its energy efficiency, which can lead to lower utility bills. According to, a tankless water heater can save a household up to $100 per year in energy costs compared to a traditional water heater. Over the lifetime of the unit, this can add up to significant savings.

Long-Term Savings

Despite the higher initial and installation costs, a tankless water heater can provide long-term savings due to its efficiency and longer lifespan. When factoring in energy savings and longer lifespan, a tankless water heater can potentially save a household thousands of dollars over its lifetime.

Is It Worth It?

While the initial costs of a tankless water heater may seem daunting, the long-term savings can make it a worthwhile investment for many households. If you plan on staying in your home for an extended period, the savings can add up and exceed the initial costs over time.

We encourage you to use our cost calculator to compare the expenses of a tankless water heater to a traditional water heater and determine if it's the right choice for your household.


We hope this DIY tankless water heater installation guide has been helpful in providing you with the information and confidence needed to tackle this project.

By carefully considering your household's water heating needs, gathering the necessary tools and materials, and following the step-by-step installation instructions, you can successfully install a tankless water heater and enjoy the benefits of continuous hot water while efficiently using energy.

Remember to also consider the long-term cost savings and maintenance requirements, as regular upkeep is key to prolonging the lifespan and efficiency of your tankless water heater.

Thank you for choosing our guide as your comprehensive tankless water heater installation resource. Happy DIY-ing!


What are the benefits of a tankless water heater?

Tankless water heaters provide several advantages, including energy efficiency, endless hot water supply, and space-saving design. They also have a longer lifespan compared to traditional water heaters.

How do I choose the right tankless water heater for my home?

When selecting a tankless water heater, consider factors such as the size of your household, desired flow rate, and available energy sources (gas or electric). It's also recommended to read customer reviews for popular models to ensure quality and performance.

What tools and materials do I need for a DIY tankless water heater installation?

For a successful installation, you'll need a variety of tools and materials, including pipe cutters, wrenches, pipe tape, and a voltage tester. It's important to have the necessary fittings, pipes, and venting components specific to your unit and installation requirements.

What steps should I take to prepare for a tankless water heater installation?

Preparation involves shutting off the water supply, disconnecting the existing water heater, and performing any necessary maintenance tasks like descaling or cleaning. It's also essential to ensure you have all the required tools and materials before starting the installation.

Where should I install my tankless water heater?

When choosing a location for your tankless water heater, consider proximity to gas and electrical connections, ventilation requirements, and easy access for future maintenance. It's important to adhere to manufacturer guidelines and local building codes.

What is involved in the actual installation process of a tankless water heater?

The installation process includes mounting the unit, connecting the necessary plumbing and electrical components, and ensuring proper venting. Each step will be detailed in our guide to help you install your tankless water heater correctly.

How do I connect the gas supply for a gas-powered tankless water heater?

Connecting the gas supply involves attaching the gas line, ensuring proper gas flow, and conducting a leak test for safety. We will provide detailed instructions on how to complete this step in our installation guide.

How do I connect the water supply for a tankless water heater?

Connecting the water supply lines requires considering hot and cold water connections, pressure relief valves, and any additional components needed. We'll provide clear instructions on how to complete this essential step.

What are the necessary electrical connections for an electric tankless water heater?

For an electric tankless water heater, you'll need to connect the electrical wiring, ensure proper grounding, and verify that the power supply meets the unit's requirements. Our guide will walk you through each of these steps.

How do I test and troubleshoot my tankless water heater after installation?

After installation, it's crucial to test your tankless water heater and troubleshoot any potential issues. Our guide will provide a checklist of tests to perform and offer solutions for common problems you may encounter.

What maintenance tasks are necessary for a tankless water heater?

Regular maintenance is important to keep your tankless water heater running smoothly. This includes tasks such as descaling, cleaning or replacing filters, and checking for any signs of wear. Our guide will outline the recommended maintenance procedures.

How can I calculate the cost and savings of installing a tankless water heater?

Calculating the cost and savings involves considering factors such as the purchase price, installation expenses, and long-term energy savings. We'll provide you with a comprehensive breakdown to help you assess the financi

Lightning fast quotes.

Our water heater experts are standing by to help. Complete our form or call to schedule service.

Get a quoteA picture of a water heaters now technician.