How to Install a Gas Water Heater

1-2 hours

Get familiar with the steps your pro installer will complete when upgrading your water heater

Gas water heaters require a gas supply, a cold water supply and a flue connection to carry away harmful gases. Learn more about the process of installing one of these units in this guide.

Safety: The Home Depot highly recommends that you hire a professional to install your water heater. Our services are available for same-day installation when you call before noon in most areas. Schedule an appointment today.

WHAT YOU NEED FOR THIS PROJECT

1
Drain the tank
Connect  gas supply line - Install Gas Water Heater

• Turn off the water and gas supply.
• Attach a garden hose to the drain valve and empty the tank.
• Turn on a hot water faucet to allow air into the system.

2
Disconnect the gas line and water lines
Disconnect  gas line water lines - Install Gas Water Heater

• Disconnect the gas line using two pipe wrenches -- disconnect the gas line at the union fitting if the pipe is galvanized, or at the flare fitting if the gas supply line is copper.
• Using two adjustable wrenches or pipe wrenches, disconnect the water lines above the tank. If the piping has been soldered into place, use a hacksaw or tubing cutter to cut the pipe. Make sure the cuts are straight.

3
Detach the gas exhaust from the flue hat
Detach  gas exhaust flue hat - Install Gas Water Heater

• Remove the screws connecting the vent to the water heater using a screwdriver or nut driver.
• Remove the old water heater – you may require help for this because older water heaters fill with sediment and are heavier than new ones.

4
Set the new water heater in place
Set water heater in place - Install Gas Water Heater

• Install the water heater in an area with at least 6 inches of clearance on all sides for ventilation. Allow unobstructed access to the burner and controls.
• Place a carpenter’s level on the side of the water heater and level it with plastic shims if necessary.
• Reconnect the flue hat to the gas exhaust vent.

5
Install the heat trap fittings
heat trap fittings - Install Gas Water Heater

• Wrap the water heater heat trap fitting pipe threads using Teflon tape. These fittings are directional and must be installed properly -- both have arrows showing the correct direction for installation.
• Attach the blue-coded fitting to the cold water inlet with the arrow facing into the water heater.
• Attach the red fitting to the hot water outlet with the arrow pointing away from the water heater.
• Tighten using a pipe wrench or adjustable pliers.

6
Install water line connections
water line connections - Install Gas Water Heater

• Measure and cut the water line connections to length.
• Reconnect the water line.

7
Connect the gas supply line
Connect  gas supply line - Install Gas Water Heater

• Before connecting the gas line, clean all threads with a wire brush and rag.
• Apply piping compound to the threads of the black pipes as you connect them.
• Assemble and tighten each fitting with two pipe wrenches.
• Install the union fitting last because it connects the new line to the existing line. When finished, open the gas supply valve and turn the water on.
• Turn on water at the tank, then turn on one or more hot water faucets to bleed air out of the system.

8
Test the gas line for leaks
Test  gas line leaks - Install Gas Water Heater

• Fill a sponge with a mixture of liquid dishwashing soap and water, and apply it to the new fitting. Check for bubbles.
• Test all connections. If there's a leak, bubbles will form on the surface and you'll have to refit the joint.

9
Light the pilot
Light pilot - Install Gas Water Heater

• Remove the burner access panel.
• Turn the knob on top of the control box to the pilot position.
• Hold a lit fireplace match or barbecue lighter to the pilot access opening.
• Press and hold down the reset button on the control box for 60 seconds after the pilot ignites.

10
Turn the control knob on
Turn control knob on - Install Gas Water Heater

• Turn the knob on top of the control box to the On position -- you should hear the burner ignite.
• If it doesn't, remove the access panel and relight the pilot.
• Replace the burner access panel and set the control at a temperature between 118 and 123 degrees.