How to Hook Up a Propane On-Demand Water Heater: A Comprehensive DIY Guide

Hooking up a propane on-demand water heater can be a complex task, but with the right knowledge and tools, it’s a project that many homeowners can tackle themselves. This comprehensive guide will walk you through the entire process, from understanding the technical specifications to the step-by-step installation instructions, ensuring a successful and safe installation.

Technical Specifications

Before diving into the installation process, it’s crucial to understand the technical requirements of a propane on-demand water heater. Here are the key specifications you need to know:

  • Propane Input: The water heater requires a 3/4″ NPT propane input. However, a 1/2″ propane feed is acceptable if the run is relatively short (up to 3 feet).
  • Gas Supply Pressure: The required gas supply pressure is 8.0 – 13.5 inch W.C. (Water Column), which is equivalent to 0.29 – 0.49 psi.
  • Propane Tank Size: A 40lb (10-gallon) propane bottle should be dedicated to the water heater, located right next to it, with a propane line only a few feet long.

Step-by-Step Installation Guide

how to hook up a propane on demand water heater

Step 1: Preparation

  1. Turn off the main water valve at the meter to shut off the water supply.
  2. Disconnect the existing water heater, if applicable, and ensure the area is clean and free of debris.

Step 2: Plumbing Connections

  1. Connect the water supply line to the water heater valves, following the manufacturer’s instructions.
  2. Tie in new hot and cold water lines to the existing water lines using copper pipe.
  3. Run the lines to the new water heater, cutting and soldering copper piping as needed.
  4. Use bell hangers to hold the pipes securely in place against the wall, making it easier to apply pipe insulation later.

Step 3: Installing the Pressure Relief Valve

  1. Install a pressure relief valve and purge valve per the manufacturer’s instructions.
  2. Turn on the water supply and check for any leaks.

Step 4: Installing the Gas Line

  1. If your current gas line is adequately sized and you can tap into the existing tee, continue the gas line to the heater location using threaded black iron pipe.
  2. Once the line is running to the unit, install a gas shut-off valve, tee, and sediment trap. Connect the shut-off valve and the sediment trap to the water heater following the manufacturer’s instructions.
  3. Using a flexible gas supply line or black pipe, run a new gas supply line from the tee to a point where it can be easily attached to the gas line of the new water heater.

Step 5: Connecting the Propane Tank

  1. Connect the propane tank to the water heater using a 3/4″ NPT propane input.
  2. Use PTFE thread seal tape on all connections, except the hand-threaded tank connector.
  3. Install a regulator and any other equipment between the tank and the heater, as specified by the manufacturer.

Step 6: Final Checks

  1. Turn on the gas, bleed the line if necessary, and check for any leaks.
  2. After checking for leaks, turn the gas line back off until the installation is complete.
  3. Open a faucet to full “hot” to purge air from the water pipes and heater, then turn the faucet off.
  4. Plug in the water heater.
  5. Insulate the hot water pipe coming from the water heater.
  6. Turn on the gas.
  7. Follow any specific start-up procedures provided by the manufacturer of your new water heater.

DIY Approach

While it’s possible to install a propane on-demand water heater yourself, it’s recommended to hire a licensed professional plumber due to the complexity of the installation process and the need for specialized skills and knowledge. However, if you decide to do it yourself, ensure that you follow all local building codes and safety considerations, and take the time to understand the manufacturer’s instructions and requirements.

Reference Links

  1. How to Install a Propane Tankless Water Heater – This Old House
  2. How to Install a Tankless Gas Water Heater – YouTube
  3. How to Install a Tankless Gas Water Heater – The Home Depot