How to Install a Propane Tankless Hot Water Heater: A Comprehensive Guide

Installing a propane tankless hot water heater can be a complex task, but with the right knowledge and tools, it can be a rewarding DIY project. This comprehensive guide will walk you through the step-by-step process of installing a propane tankless hot water heater, providing you with the technical details and expert insights to ensure a successful installation.

Preparing for the Installation

Before you begin the installation process, it’s crucial to ensure that you have all the necessary tools and materials on hand. This includes:

  • Pipe cutter
  • Pipe wrench
  • Soldering torch and solder
  • Teflon tape
  • Adjustable wrench
  • Level
  • Drill and drill bits
  • Stud finder
  • Tape measure
  • Safety gear (gloves, goggles, and a dust mask)

Additionally, you’ll need to turn off the main water valve at the meter and the gas supply to the old water heater. This is a crucial safety step to prevent any water or gas leaks during the installation process.

Removing the Old Water Heater

how to install a propane tankless hot water heater

The first step in the installation process is to remove the old water heater. This involves disconnecting the water supply lines, the gas line, and the electrical connections. Be sure to have a bucket on hand to catch any remaining water in the tank.

Once the old water heater is removed, you’ll need to cut into the existing water-supply pipes to prepare for the new tankless heater. Use a pipe cutter to make clean, straight cuts, ensuring a proper fit for the new connections.

Installing the Propane Tankless Hot Water Heater

  1. Mounting the Heater: Locate a suitable wall space for the tankless heater, ensuring that it’s close to the existing water and gas supply lines. Use a stud finder to locate the wall studs and mark the mounting points. Drill pilot holes and secure the heater to the wall using the provided mounting hardware.

  2. Connecting the Gas Line: Run a threaded iron pipe from the outdoor propane tank to the heater. Use a pipe wrench to tighten all connections, and be sure to use a union fitting to connect the gas pipe to the heater.

  3. Connecting the Water Supply: Run copper pipe from the existing water-supply line to the heater. Solder all copper connections using a soldering torch and lead-free solder.

  4. Connecting the Electrical: Plug the heater into a nearby electrical outlet, ensuring that the outlet is properly grounded.

  5. Adjusting the Temperature: Set the water temperature to 120 degrees Fahrenheit (49 degrees Celsius) at the heater’s control panel. This is the recommended temperature to prevent scalding and maximize energy efficiency.

  6. Checking for Leaks: Open the main water valve and check all connections for any signs of leaks. Tighten any loose fittings as needed.

  7. Turning on the Propane: Once you’ve confirmed that there are no leaks, turn on the propane supply to the heater.

Finalizing the Installation

After completing the installation, it’s essential to test the new propane tankless hot water heater to ensure it’s functioning correctly. Turn on a hot water tap and verify that the heater is heating the water as expected.

If you encounter any issues or have concerns during the installation process, it’s recommended to consult with a licensed plumber or HVAC technician for assistance.

Technical Specifications and Considerations

  • Skill Level: Installing a propane tankless hot water heater is a complex task that requires a high level of expertise. It’s generally recommended to hire a licensed professional plumber or HVAC technician to ensure the installation is done correctly and safely.

  • Cost: The cost of the propane tankless hot water heater itself can range from $950 to $1,150, depending on the model and features. Additionally, the installation cost can range from $300 to $400, depending on the complexity of the project and the local labor rates.

  • Estimated Time: The installation process can take between 3 to 4 hours, depending on the complexity of the project and the experience of the installer.

  • Ventilation Requirements: Propane tankless hot water heaters require proper ventilation to ensure safe operation. The heater must be installed in a well-ventilated area, and the exhaust must be properly vented to the outside.

  • Electrical Requirements: Propane tankless hot water heaters require a 120-volt electrical connection to power the control panel and other electronic components.

  • Maintenance: Regular maintenance, such as flushing the system and inspecting the venting, is essential to ensure the long-term reliability and efficiency of the propane tankless hot water heater.

By following the step-by-step instructions and considering the technical specifications outlined in this guide, you can successfully install a propane tankless hot water heater in your home, ensuring a reliable and energy-efficient hot water supply for years to come.


  1. Reddit Discussion on Propane Tankless Water Heater Install
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  5. Home Depot: How to Install a Tankless Gas Water Heater