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Gas Water Heater Installation: Step-by-Step Directions to Do It Yourself

Gas Water Heater Installation: Burner

Gas water heater installation may seem like a job for the pro’s, but actually, it’s not as difficult as you may think. Certainly, the easiest way to get the job done is to hire a professional to do the work for you. However, if you want to save a little money and achieve a feeling of accomplishment, installing your gas water heater is a great DYI project.

When selecting a new water heater, it’s generally best to stay with the same fuel type (gas or electric) unless there’s good reason to switch. It’s also a good idea to check with a local plumbing inspector. They can share the local plumbing codes with you, as well as let you know if you’ll need a municipal permit.

Another point to consider is how to dispose of your old water heater.  If you hire a professional you won’t need to worry about this because they will haul your old water heater away for you. Still, if you enjoy doing projects yourself, and you would like to save yourself some money, replacing a gas water heater is not hard.


What to Consider Before Installing your Gas Water Heater

If your water heater is over 10 years old, there’s a good chance that it has reached the end of its life and it will need to be replaced. However, before you buy a new water heater, it’s worth your effort to troubleshoot the problem. If your water heater is leaking, many times the issue is repairable. However, if the source of the leak is from the tank itself, you will need to replace the unit.

Tools and Supplies Needed for Gas Water Heater Installation

  • Tape measure and pencil
  • Wire brush
  • Utility knife
  • Wrench
  • 3/8″ Nut driver or a drill with a 3/8″ bit
  • Pipe Joint Compound: Gas plumbers tape (optional), or teflon tape (optional)
  • Self tapping sheet metal screws
  • Soap & Water: Leak detection solution (optional)
  • Earthquake Straps
  • Adjustable vent pipe (Ameri-vent)
  • 2 Flexible hoses
  • Flexible gas line

A Few Things to Keep in Mind Before Installing your Gas Water Heater

  • Check the label on your old water heater. It should list the annual energy useage and the tank size. Both of these facts are helpful when you are selecting your new water heater.
  • We recommend checking your water heater vent system to ensure that it is properly working before removing your old unit.
  • Disconnect and remove your old heater. Drain your heater first and use a hand truck to move it outside.
  • If your tank has an excessive amount of sediment build-up, the drain valve may clog. This article will help you drain the tank.
  • Handle the vent pipe with care, if it is in good condition you can use it with your new water heater.
  • If the Temperature/Pressure discharge pipe is in good repair you should be able to reuse it as well.
  • If your water heater was plumbed with copper pipes you may need to cut the copper pipes with a tubing cutter. If so, be sure to leave as much pipe as possible.
  • We highly recommend placing your new water heater into a drain pan and routing the water to a floor drain.
  • Be sure to leave enough room for to perform regular maintenance on your new water heater.

Installing Your Gas Water Heater

Step 1

Install Earthquake Straps

Measuring for Earthquake Straps for a Gas Water Heater Installation

  • Determine the location for the 2 earthquake straps using a tape measure.
    • These seismic straps will brace the tank against the wall during an earthquake and help prevent it from toppling over.
    • Measure from the ground up on the water heater and mark the wall appropriately.
      • The top earthquake strap should be a few inches below the Temperature & Pressure Valve.
      • The lower strap should be a few inches above the gas regulator.
  • Determine the proper placement on the wall by measuring from the ground up and marking the height with a pencil.

Mounting earthquake straps when installing a gas water heater

  • Mount the earthquake strap brackets onto the wall. Be sure the screw “catches” a stud.
  • The earthquake strap should rest next to the tank.
    • If necessary “swing” the bracket 180 degrees before fully tightening the screws.
  • Move the new water heater into place.
    • Set the water heater into a drain pan.
    • Line-up the existing plumbing to the water heater’s inlet and outlet connectors.
    • Be sure to leave room between the wall and the water heater to perform future maintenance.
  • Do NOT strap the water heater into the earthquake straps yet.

Step 2

Connect Water Supply

Preparing the pipes to install a gas water heater

  • Clean the cold and hot water line threads.
    • Use a wire brush if necessary.
  • If the cold water supply does not have a shut-off, we highly recommend installing one.
    • We recommend using a ball valve.

Connect the water lines on a gas water heater installation

  • Connect the hot and cold water supply lines.
  • If you are using copper flexible water lines (as shown in the video), be careful to avoid kinking them when installing.
    • Loop the flex connector around using the technique shown in the video.
  • Flexible water supply lines are a little easier to work with.
  • Keep the hot and cold water supply lines clear of the vent area.
    • Be sure to leave a little slack in the hot and cold water supply lines.
  • Some areas require the use of dielectric nipples between the water heater and the water line.
    • Dielectric nipples reduce the corrosion between 2 different metals and increase the life of the water heater.
    • Check your new water heater before purchasing dielectric nipples, as sometimes they are preinstalled. If your water heater did not come with dielectric nipples, we highly recommend purchasing a set.
    • Line the threads with Teflon tape or pipe thread sealant to prevent leaking.

 Step 3

Install the Vent Hood

Installing the hood on a gas water heater installation

  • Attach the vent hood over the flue on the top of the water heater.
    • Follow the instructions that came with your water heater, as the process varies among different manufacturers.
    • Use self-tapping sheet metal screws to secure the vent hood into place.

Step 4

Install the Vent Piping

Installing the vent pipe for a gas water heater

  • If your vent pipe is in good condition, you should be able to reuse it with your new water heater.
    • Check your water heaters instruction manual for the correct vent pipe diameter.
    • A reducer should NOT be used if the recommended vent pipe diameter is larger than the vent hood.

Installing the vent joints on a gas water heater

  • Using adjustable vent pipe, insert one end into the water heater vent hood and begin attaching the other pipe sections. Be sure to check your water heater manufacturer manual for the correct diameter.
  • Adjust the elbows prior to installing to allow the vent pipe to align as closely to straight as possible.
  • Secure all the vent pipe sections by pushing them together so that each fits tightly to the other.

Securing vents when installing a gas water heater

  • Use self-tapping sheet metal screws to secure the vent sections to the water heater vent hood and the other vent sections.
    • Use at least 2 screws at each connection. Check your local code for requirements.

Step 5

Install the Gas Connection

Prep the gas supply prior to connecting when installing a gas water heater

  • Double check that the gas supply is in the OFF position.
  • Using a wire brush, clean the pipe fitting on the supply pipe.
  • Flush the line by opening and closing the valve.

Preparing the gas control valve when installing a gas water heater

  • Remove the sticker and plug on the gas control valve. This is where the gas line will contect.
  • Unscrew the gas nipple on the flexible gas line.
    • Flexible gas lines are required in many areas, especially areas prone to earthquakes. It is always a good idea to check if they are allowed in your area.

Preparing the gas line when installing a gas water heater

  • Paint pipe joint compound onto the thread of the gas nipple.
    • Avoid covering the first few threads with pipe joint compound as shown in the video.
  • We recommend using Gas Plumbers Tape which is yellow, and not as messy. NEVER use white Teflon tape.

Installing the connector to the gas control valve when installing a gas water heater

  • Attach the gas nipple into the gas control valve.
    • Tighten the gas nipple with a wrench. It should be FAIRLY TIGHT.
    • Be careful of damaging the gas control valve while tightening.
      • We recommend tightening the nipple with 2 wrenchs to prevent damage to the gas control valve. One wrench on the nipple and the other holding the gas control valve.

Attach the gas line when installing your gas water heater

  • Attach the gas flex connector line to the gas line and the water heaters gas control valve.
    • Be careful not to kink the line. Loop the excess line if necessary.
  • Hand tighten the connectors and then, use a wrench to tighten slightly tighter.
  • Do NOT turn on the gas.

Step 6

Fill the Tank

Fill the Tank during a gas water heater installation

  • Open the water inlet valve and begin filling the tank with water.
    • Open a hot water faucet, this will alert you that the tank is full.
  • Check for leaks on each end of the two flexible water lines.
  • When water runs from the hot water faucet, the tank is full.
    • Allow the water to run for several minutes to eliminate the air in the tank. The water will sputter until the tank is full and all air has been bled from the tank and lines.

Step 7

Connect the Earthquake Straps

Secure the earthquake straps when installing your gas water heater

  • Pull the earthquake straps around the water heater and connect them together.
    • Do not pull the straps too tight. They should be snug, but not too tight.
  • Use clips to fasten the excess strap.

Step 8

Connect the T&P Drain Pipe

Installing the T&P drain pipe when installing a gas water heater

  • You may be able to reuse your T&P drain pipe from your old water heater.
  • If you need to make a new one, measure and cut a copper pipe with a tube cutter.
    • If you do not have a floor drain, place a bucket under the T&P drain pipe. The end of the drain pipe should be no higher than 6 inches above the ground or bucket.

Step 9

Light the Pilot

Lighting the Pilot when installing a Gas Water Heater

  • Turn the gas supply ON.
  • Follow your water heater’s owners manual to light the pilot, as the process can vary between manufacturers.
  • Place the lower dial on the gas regulator to “Pilot Lighting”
  • Turn the control knob on the gas regulator to PILOT mode, then press and hold the control knob down.
  • Wait a few seconds and then press the ignitor button, while you are pressing the control knob down.
  • Some water heaters have an indicator light to alert you that the pilot is lit, and others have a sight glass that will allow you to visually check if the flame caught.
    • If the flame went out: Repeat the above steps.
    • If the flame caught:
      • Continue pressing the control knob down for 45 to 60 seconds.
      • Release the control knob and check that the pilot is still lit.
      • If the pilot is still lit, turn the control knob to the ON position.
  •  Turn the lower dial to your desired water temperature.
    • Use the factory recommendation setting as a starting point.
    • 120 degress is the recommeded temperature setting.

Step 10

Test Gas Lines for Leaks

Check for gas leaks when installing your gas water heater

  • Check for gas leaks by spraying all gas connections.
    • Mix your own solution of 1 part dish detergent and 2 parts water. Or, use Leak Detection Solution if you prefer.
  • If you notice any “bubbling” it is an indication that gas is escaping.
    • Tighten the loose connection with a wrench and then check again.

Watch the Video

A Few Other Considerations

  • Always check your vents to make sure they are properly drawing – call a professional if necessary.

  • We highly recommend having a carbon monixide detector near your gas water heater. They are inexpensive and available at Amazon.
  • After a couple of hours, check the T&P discharge pipe. If the pipe is dripping, there is a good chance that the pressure inside your tank is too high.