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How To Install A New Igniter And Flame Sensor On A Gas Water Heater That's Already Disassembled

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The igniter and flame sensor unit on a gas water heater sense when the pilot light is lit and trigger the release of gas and the power of the burner assembly. Without a working igniter or flame sensor, the water heater won't receive the gas or heat source needed to warm your water and you will be left with a cold shower.

Replacing the igniter and flame sensor isn't difficult if you have the original part already removed and the water heater is still disassembled. Don't have the heater disassembled? Follow the instructions in reverse to get to the starting point. Or call in a plumbing repair service to perform the part installation.

What You Need: 

  • New igniter and flame sensor set
  • Screwdriver
  • Pliers
  • Socket wrench
  • Wrench

Step 1: Install the New Flame Sensor

Make sure the water heater is unplugged and that the gas shut-off valve is turned off, which should be done whenever the unit is opened up. You should have the heater's burner assembly out of the unit and placed on a table for easier working.

If the burner tube is still detached from the burner cover, feed the burner tube forward through its hole in the burner cover. Slide the burner tube gasket into place and secure. Align the new igniter and flame sensor unit onto the burner tube bracket and attach the mounting screws to secure.

Locate the vapor sensor wires left unhooked from when you removed the original igniter and flame sensor. Feed the wires back through the burner cover and push the grommet into place to secure. Connect the ends of the wires to the appropriate terminals in the vapor sensor using the pliers for assistance.

Step 2: Put the Water Heater Back Together

Pick up the entire burner assembly and line the assembly up with the hole in the water heater and the interior support brackets. Push straight in slowly to insert the assembly and ensure the assembly is on the brackets.

Use a socket wrench to reattach the mounting nuts to each end of the burner cover. Connect both wire harnesses to the bottom of the control valve making sure you plug the wires into the correct terminals.

Snap the vapor sensor bracket back over the tank wall at the bottom near the burner cover. Attach the burner tube to the control valve and twist up its connecting nut until the nut has enough pressure that you need to switch to the wrench to finalize.

Replace the access cover. Plug the water heater back into the electrical socket and turn on the gas shut-off valve. Give the tank some time to warm up before testing the water. If you still lack hot water, call for a plumbing repair.