Kenmore waterheater piezo innotor won't re-light

http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#pressure

3 flashes, failed pressure switch?
Test pressure switch
Gene

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The hot side of the faucet is most likely plugged with something that came up thru the water system. The average thankless waterheater requires at least 1/2 to 3/4 gpm flow rate for the unit to sense flow and turn on. If there is not enough flow it will not fire and heat the water. Not sure about this particular unit but a few require at least one full gallon per minute flow. So chances are that if you fix the faucet, you fix the hot water issue at the same time

1) Clean air intake (flame arrestor):located under combustion parts and look for broken glass from TRD
http://waterheatertimer.org/How-to-repair-Rheem-TRD.html

2) Troubleshoot by type of gas control, and link to AS Smith service manuals
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

3) Add a comment with more information
http://www.thetankatwaterheaterrescue.com/forums/forum3/

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Gas water heaters are a huge field:
More information is needed for correct do-it-yourself answer. Add a comment and include what steps you have taken and what you observed at the pilot light. Include description of gas control valve.
The combustion parts may need to be cleaned, the thermoscouple could be bad, misaligned thermocouple, the system locked out from FV flammable vapor event, or overheating caused ECO energy-cut-off to trip, or air in gas line, low gas pressure, or dirty air intake, bad venting, improper venting, bad gas control valve, negative pressure, tight house, lack of combustion air, hot attic, exposure to chemicals in air, rusted parts, etc.

Add a comment any time.
Or contact Rheem at 1-800-432-8373
Or continue reading to find correct resource:

You have Rheem 30 gallon ultra low-nox gas water heater.
Knowing the gas valve is necessary for troubleshooting.
The 40 and 50 gallon version of this water heater have electronic self-diagnostic gas valve as shown on following link.
http://www.rheem.com/product.aspx?id=F4AE5B83-899F-4AC0-B09D-22A6770BE799
Open following link to identify gas valve, then add a comment and describe which gas valve you have.
http://waterheatertimer.org/How-to-adjust-water-heater-temperature.html#intelli

Open following link for general do-it-yourself resources, with reading resources, service manuals, images that illustrate cleaning and different gas water heater parts
http://waterheatertimer.org/How-to-install-gas-water-heater.html#troubleshoot

Add a comment for more help.

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there could be a small blockage in the pilot light gas nozzle which just need cleaning

turn the water flow off and control off and hold the two arrow buttons together
then use the up arrow to get to e and the down arrow to get to 1 what do you see?

It is normal problem because u r heater is so old
out of company warranty so open it and clean it

NOTE

dont touch it after use means open it before use

means when it is not use in 1 hours because heater contain power in one hour after use

it sounds like the flue pipe out side may have something blocking it , it has a fresh air return on it and when the unit is blowing out it also pulls in the outside air, make sure ther is nothing in the way making the air circulate back in,

Check voltage at the gas valve and at the thermocoupling. If you are reading more then 24 volts at the gas valve then replace it, or less then replace it also