Introduction: Installing a Rheem 40 Gallon Gas Water Heater can provide efficient and reliable hot water for your household needs. Please follow this guide carefully to ensure a safe and proper installation.

Tools and Materials Needed:

  • Adjustable wrenches
  • Pipe wrenches
  • Screwdrivers
  • Teflon tape
  • Gas leak detector or soapy water
  • Venting pipes and fittings (as required by model)
  • Water supply lines
  • Drip pan (if required)

Safety Precautions:

  • Turn off the water supply and gas supply before beginning installation.
  • Ensure the installation area is well-ventilat.
  • Read all instructions and warnings provided by Rheem.

Installation Steps:

  1. Preparation:
    • Place the water heater in a suitable location, adhering to all local codes and regulations regarding clearance and venting requirements.
    • Ensure the floor is level and capable of supporting the weight of the heater filled with water.
  2. Water Line Connection:
    • Apply Teflon tape to the threads of the water supply lines.
    • Connect the cold water supply line to the water heater’s “Cold” inlet, usually marked blue.
    • Connect the hot water output, usually marked red, to your home’s hot water piping.
  3. Gas Line Connection:
    • Apply Teflon tape designed for gas lines to the threads of the gas supply line.
    • Connect the gas line to the gas control valve on the water heater using a pipe wrench. Ensure all connections are tight and secure.
    • Check for leaks using a gas leak detector or soapy water. Bubbles forming indicate a leak that must be fixed immediately.
  4. Venting Installation:
    • Install the venting system according to the manufacturer’s instructions and local codes. This may involve securing vent pipes and making sure they lead outdoors without any obstructions.
  5. Filling the Tank:
    • Open the cold water supply valve to fill the tank.
    • Open several hot water faucets in the house to bleed air from the system.
    • Check for any leaks in the water connections and fix if necessary.
  6. Lighting the Pilot:
    • Follow the manufacturer’s instructions for lighting the pilot. This usually involves setting the control knob to ‘pilot’ and using an ignition button or a manual match lighting method.
  7. Final Setup:
    • Once the pilot is lit and stable, set the temperature to your preferred setting.
    • Inspect the installation area once more for any signs of leaking or other issues.


  • Register your product with Rheem for warranty purposes.
  • Keep the area around the water heater clear of flammable materials and debris.


Your Rheem 40 Gallon Gas Water Heater is now installed and ready for use. Regular maintenance is recommended to ensure efficient operation and to extend the life of your water heater.