How to Convert From Electric to Gas Hot Water Tanks

Contact your local codes department to ensure you comply with all current local building codes prior to converting your old electric water heater to a new gas water heater. Check your home to see if you already have a gas line available to connect your new gas water heater. If no gas line is present, you will need to contact a qualified plumber to run the line. Running a new natural gas line is not a do-it-yourself project.

Shut off the breaker that provides electricity to your old water heater. Shut off the water supply to the water heater. Connect a garden hose to the old water heater's drain valve and place the other end of the hose in the sink, bathtub or basin. Turn on a hot water faucet in your home to allow air to flow through the system, then open the water heater's drain valve to empty the tank.

Locate the electricity line that powers your old water heater. Remove the safety plate. Disconnect the electric lines and cap them off. Disconnect both the hot water outlet line and the cold water inlet line from the top of the tank using a wrench. Remove the old electric water heater. If your tank is secured with an earthquake strap, you will need to remove it. Move the old tank out of the way, using caution as the tank may be heavy or awkward. You may require assistance from another person. Contact your local solid waste disposal department to determine the proper method of disposing of the old tank.

Install a vent pipe system for your new gas water heater. The type of vent pipe system required may vary based on the location of the water heater and the style of your home. You can connect the water heater vent to either a vertical gas vent or a certified chimney. Contact your local codes department to ensure compliance with all local codes.

Set your new gas water heater in place. Make sure there is at least 6 inches of clearance on all sides of the tank for proper ventilation. Place a carpenter's level along the side of the tank to ensure your new water heater is level. Adjust the base with plastic shims as necessary. Ensure the water heater is completely stable before proceeding.

Settle the flue hat into place and connect it to the gas exhaust vent. Install a new pressure-relief value in the opening designated on the tank. Do not use the old value from your old water heater. If your new water heater requires cold water inlet and hot water outlet nipples, install them into the proper openings on the top of the tank. Connect the cold water line to the cold water inlet nipple and the hot water line to the hot water outlet nipple. The easiest type of water connections involve flexible copper connectors.

Connect the gas line to the water heater. Make sure you adhere to all state and local codes, which may require the application of natural gas-rated Teflon tape or other sealants to ensure a proper seal. Keep pressure on a back-up wrench to maintain the control valve and thermostat assembly in proper alignment. Do not overtighten the connection. Turn on the gas supply and check for leaks. Engage a qualified service tech to purge the air from the gas lines.

Turn on the cold water supply to the water heater and allow the tank to completely fill. Leave a hot water faucet turned on to allow for air circulation. Check the water lines for leaks. Water running from the hot water faucet will indicate the when tank is filled. Turn off the hot water faucet. Follow the manufacturer's instructions for lighting the pilot light.