Tips for Installing a Tankless Water Heater at Home


If you’re considering upgrading your home’s water heating system, a tankless water heater might be the ideal choice. Tankless water heaters, also known as on-demand or instant water heaters, provide several advantages, including energy efficiency, endless hot water, and space-saving design. However, the installation process can be quite different from traditional tank-style water heaters. In this guide, we’ll walk you through the essential tips for installing a tankless water heater at home, ensuring a smooth transition to efficient and continuous hot water.

Evaluate Your Needs

Before diving into the installation process, assess your household’s hot water needs. Consider factors such as the number of bathrooms, appliances, and fixtures that require hot water. This evaluation will help you determine the appropriate size and capacity of the tankless water heater to meet your demands adequately. By understanding your specific requirements, you can choose a tankless water heater that provides the right flow rate and temperature rise to meet your family’s needs.

Choose the Right Location

Selecting the optimal location for your tankless water heater is crucial. These units are typically compact and can be mounted on walls or placed in small alcoves, providing flexibility in placement. Ideally, install the unit close to the main point of use to minimize hot water distribution time.

When choosing a location, consider the following:

  • Proximity to gas or electrical connections.
  • Accessibility for maintenance and servicing.
  • Proper ventilation and exhaust requirements.
  • Access to plumbing connections for hot and cold water supply.

Keep in mind that tankless water heaters should be installed indoors to protect them from freezing temperatures and harsh weather conditions.

Ventilation and Exhaust

Tankless water heaters produce exhaust gases that must be vented safely outdoors. Ensure proper ventilation by following the manufacturer’s guidelines and local building codes. You may need to install stainless steel venting pipes that are corrosion-resistant and heat-resistant.

Proper venting is critical to the safe operation of your tankless water heater. The type of venting system required depends on the unit’s fuel source (gas or electric) and whether it’s a condensing or non-condensing model. Consult the manufacturer’s instructions and a professional plumber to ensure correct venting.

Gas or Electric

Tankless water heaters are available in both gas (natural gas or propane) and electric models. The choice between gas and electric depends on your home’s existing infrastructure and your preferences. Gas models typically offer higher flow rates and are suitable for larger households with higher hot water demands.

Consider the following when deciding between gas and electric tankless water heaters:

  • Availability of gas lines or electrical service in your home.
  • Gas supply pressure and capacity for gas models.
  • Electrical panel capacity and wiring requirements for electric models.
  • Local utility costs and energy efficiency preferences.

Select the type of tankless water heater that aligns with your home’s infrastructure and hot water needs.

Plumbing Connections

Proper plumbing connections are essential for the efficient operation of your tankless water heater. Ensure that the unit is connected to both cold water and hot water lines. Additionally, consider installing isolation valves for easy maintenance and servicing in the future. It’s advisable to consult a professional plumber for the plumbing connections to ensure proper installation and avoid leaks or water pressure issues.

Consider Flow Rate

Tankless water heaters are rated by their flow rate, measured in gallons per minute (GPM). The flow rate determines how much hot water the unit can deliver at a given time. Select a tankless water heater with an appropriate flow rate to meet your household’s demands. A plumber can help you calculate your required flow rate based on your usage patterns.

To determine the right flow rate for your home, consider the simultaneous use of hot water in your household. For example, if you often run the dishwasher and take showers simultaneously, you’ll need a tankless water heater with a higher flow rate to ensure an adequate supply of hot water to all fixtures.

Electrical Requirements

If you opt for an electric tankless water heater, ensure that your home’s electrical system can accommodate the unit’s power requirements. You may need to upgrade your electrical panel or wiring to support the new appliance. Consult an electrician to assess your electrical system and make any necessary upgrades to support the tankless water heater.

Proper Gas Supply

For gas tankless water heaters, it’s crucial to have an adequate and correctly sized gas supply line. Consult with a professional plumber to ensure that your gas line can provide the necessary gas flow for the unit to operate efficiently.

Gas supply considerations include:

  • Gas line sizing to match the heater’s gas input requirements.
  • Proper gas pressure to ensure consistent performance.
  • Gas line materials suitable for gas connections.

Proper gas supply is essential for the safe and efficient operation of gas tankless water heaters. An experienced plumber can assess and address gas supply requirements during installation.

Safety Considerations

Safety should be a top priority during installation. Ensure that your tankless water heater is equipped with safety features, such as automatic shutoff in case of overheating or a flame failure device. Additionally, consider installing a carbon monoxide detector near the unit, especially if it’s a gas-powered model. Carbon monoxide detectors provide an additional layer of safety by alerting you to the presence of this odorless, toxic gas. Install one near your tankless water heater and other gas appliances.

Professional Installation

While some homeowners may be skilled in DIY projects, tankless water heater installation is a task best left to professionals. A licensed plumber or technician with experience in tankless water heater installation can ensure that the unit is properly connected, vented, and functioning safely.

Professional installation offers several benefits:

  • Compliance with local building codes and safety regulations.
  • Proper sizing and placement of the tankless water heater.
  • Correct venting and exhaust setup.
  • Installation of safety features and shutoff mechanisms.

Investing in professional installation ensures the long-term performance and safety of your tankless water heater.

Regular Maintenance

Once your tankless water heater is installed, it’s essential to perform regular maintenance to ensure its longevity and efficiency. Periodically flush the unit to remove mineral buildup, which can affect performance. Follow the manufacturer’s maintenance guidelines to keep your tankless water heater in top condition.

Maintenance tasks for tankless water heaters may include:

  • Flushing the unit to remove mineral deposits: This prevents clogs and maintains efficient heat transfer.
  • Checking for leaks or loose connections: Inspect plumbing and gas connections for signs of leaks.
  • Cleaning or replacing air filters: Ensure proper airflow for combustion and ventilation.
  • Testing safety features: Verify that safety mechanisms are functioning correctly.

Regular maintenance can extend the lifespan of your tankless water heater and maintain its energy efficiency, providing consistent hot water for your household.

Consider Water Quality

Water quality can impact the performance and lifespan of your tankless water heater. If your area has hard water, consider installing a water softener to reduce mineral deposits in the unit. This will help maintain efficiency and prolong the unit’s life.


Hard water contains minerals like calcium and magnesium that can accumulate in the heat exchanger of your tankless water heater over time. This buildup reduces the unit’s efficiency and may require more frequent maintenance. A water softener can help prevent these issues by treating the incoming water supply.


In conclusion, installing a tankless water heater at home can be a rewarding upgrade that provides energy-efficient and endless hot water. However, it’s crucial to assess your household’s needs, choose the right type and size of unit, and ensure proper installation by a licensed professional. By following these tips and considering safety and maintenance, you can enjoy the benefits of a tankless water heater for years to come. Remember that professional guidance and installation are key to a successful transition to this efficient water-heating technology.

Pat Baker is a cold-adverse person, a lover of DIY home renovation projects, and a writer for water heater replacement specialists in the Tucson area.

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