How to Change an Old Propane Water Heater: A Comprehensive Guide

Changing an old propane water heater can be a daunting task, but with the right knowledge and tools, it can be a straightforward process. This comprehensive guide will walk you through the step-by-step process of removing your old water heater and installing a new one, ensuring your home has a reliable and efficient hot water supply.

Preparing for the Replacement

Before you begin the replacement process, it’s essential to gather the necessary tools and materials. You’ll need a pipe wrench, a reciprocating saw, a level, a soapy water solution, and the appropriate personal protective equipment (PPE), such as gloves and safety glasses.

Additionally, you’ll need to determine the size and specifications of your new propane water heater. Consider the tank size, first-hour rating (FHR), energy factor (EF), gas input, and venting requirements to ensure the new unit is compatible with your home’s infrastructure.

Removing the Old Water Heater

how to change old propane water heater

  1. Shut off the Gas and Water Supply: Begin by turning off the gas supply valve and the water supply valves to the old water heater. This will prevent any gas or water leaks during the removal process.

  2. Drain the Tank: Connect a hose to the drain valve at the bottom of the tank and drain the water from the tank. This will make the tank lighter and easier to handle.

  3. Disconnect the Connections: Using a pipe wrench, disconnect the gas line, water lines, and flue pipe from the old water heater. Be careful when removing the flue pipe, as it may be fragile.

  4. Remove the Tank: Once all the connections are disconnected, carefully lift and remove the old water heater from its location. This may require the assistance of a second person, as the tank can be quite heavy.

Preparing the Installation Area

  1. Clean the Area: Thoroughly clean the area where the new water heater will be installed. Remove any debris or dust that may have accumulated over time.

  2. Check the Floor: Ensure the floor is level and can support the weight of the new water heater. If the floor is uneven, consider using shims to level the unit.

  3. Inspect the Flue Pipe and Chimney: Examine the existing flue pipe and chimney to ensure they are in good condition and can accommodate the new water heater’s venting requirements. If necessary, make any necessary repairs or replacements.

Installing the New Water Heater

  1. Position the New Water Heater: Carefully place the new water heater in the desired location, making sure it is level and stable.

  2. Connect the Flue Pipe: Attach the new flue pipe to the water heater using the appropriate ductwork. Seal the connections with silicone to prevent any leaks.

  3. Connect the Water Lines: Use 1/2″ copper pipes and push connectors to connect the water lines to the new water heater. Ensure the connections are tight and secure.

  4. Reconnect the Gas Piping: Reattach the gas line to the new water heater using pipe dope to create a tight seal.

Checking for Leaks and Lighting the Pilot

  1. Check for Leaks: Turn on the gas and water supply valves and inspect the connections for any leaks. Use a soapy water solution to check for bubbles around the connections. Tighten the connections and reapply pipe dope as needed to eliminate any leaks.

  2. Light the Pilot: Follow the manufacturer’s instructions to light the pilot and set the desired temperature. Ensure the pilot is lit and the burner is working correctly by checking the view window.

Choosing the Right Propane Water Heater

When selecting a new propane water heater, consider the following technical specifications:

Specification Description
Tank Size The tank size should be based on your household’s hot water needs. A 40-gallon tank is suitable for most families, but larger households may require a larger tank.
First-Hour Rating (FHR) The FHR is the amount of hot water the water heater can deliver in an hour. Choose a water heater with an FHR that meets your household’s hot water demand.
Energy Factor (EF) The EF is a measure of the water heater’s energy efficiency. A higher EF means the water heater is more efficient, which can save you money on your energy bills.
Gas Input The gas input is the amount of gas the water heater requires to heat the water. Ensure your gas supply can handle the water heater’s gas input.
Venting Requirements Check the water heater’s venting requirements to ensure they match your chimney and flue pipe specifications.

By following these steps and considering the technical specifications, you can successfully change your old propane water heater and enjoy a reliable and efficient hot water supply in your home.


  1. How to Safely Change a Propane Hot Water Heater – YouTube
  2. At least 18 year old hot water tank. No issues (yet), would you recommend flushing and changing the anode rod? – Reddit
  3. How to Replace a Tank-Type Water Heater | Ask This Old House