Depends on gas control valve, and if cause is overheating high-limit event or FVIR flammable vapor event.
Turn off water heater when using flammable vapors, clean burner parts to prevent overheating.
1) GSW Residential power vent gas water heater with FVIR system:
Some models have intelli-vent gas contol
Others have robershaw gas control with auto-reset
2) Parts manual shows #15 'auto-reset' high limit switch on the blowerhttp://www.gswpartsonline.com/model/27484http://www.gswpartsonline.com/schematic/137/view
3) Possible manual:http://www.gsw-wh.com/pdfs/GPD135NInstall.pdf
Shows resettable lockout page 15
Water temperature must be 120 degree F or lower for reset. Unplug power cord, and then plug back in and wait 15 minutes or 60 minutes depending on gas control valve.
Some intelli-vent controls must be replaced when 195 degree high limit event locks out the water heater.
If high-limit lockout repeats, then gas control must be replaced.
Also clean burner parts, air intake, and make sure flame is clear blue. and not yellow-or-orange.
4) Intelli-vent service manual might apply to your water heater:http://waterheatertimer.org/pdf/Intellivent-service-manual.pdf
If FVIR flammable vapor event locked out heater, then unplug heater and plug back in.
Immediately press two temperature buttons. Wait for green light to blink. Release buttons.
Page 34 in troubleshoot chart.
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