Pressure/Temperature Relief Valves on water heaters are NOT a one time device.
There is no wax to melt and opening does not make them useless.
They operate on temperature (210*F) and on pressure (150#....typically close when pressure drops below 125#)
They have a lever that can be operated to manually open them. Spring loaded snap shut.
Exercising them via lever once a year is a normal test.
OP:
The gas control/thermostat are one complete unit.
This should work on your 2009 year model....check the gas inlet/outlet size.......
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