Pilot light won’t stay lit

Atb1976

New member
May 23, 2020
2
McHenry Illinois
I have a Hayward h150.
When I push the black knob down to light the pilot light after holding it down for at least a minute the light goes out. Is it the Gas valve? Or can it just be the whole assembly/ thermo generator?
 

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swamprat69

Well-known member
Mar 30, 2019
241
Las Vegas, NV
Normal sequence for lighting your millivolt (MV) pilot would be to turn the gas valve knob to the "pilot" position and push it down to allow gas flow to the pilot. While holding the gas valve knob down, push the piezoelectric " spark generator" button multiple times until you observe a pilot flame. Keep holding the gas valve knob down for about 2 minutes. At this time ( after 2 minutes ) you can use a multimeter to measures the output of the thermopile in DC millivolts (the part that sits in the pilot flame and has 2 electrical leads attached to the gas valve ). It should measure 325 MV or above with no load. If it doesn't measure 325 MV or above with a good strong "blue" pilot flame, replace the thermopile.
 

Atb1976

New member
May 23, 2020
2
McHenry Illinois
ThAnk you for the sequence. I have held the pilot gas button down for well over 2 minutes. As soon as I release the button it goes out. I am going to replace the whole assembly thermopile and all.
the question I have is if the pilot light goes out as soon as I release the button does that say the valve is bad?
I always thought the thermopile ha fro do with the actual lighting of the heater for it to run the heating element.
I am learning, not a pro.
Thank you
 

swamprat69

Well-known member
Mar 30, 2019
241
Las Vegas, NV
The thermopile actually generates the voltage ( in Millivolts) that operates the gas valve when it is heated in the pilot flame. This type of system needs no external supply voltage to the heater to operate the gas valve ( used even in large commercial water heaters as in apartment complexes ) to avoid having to run electrical supply to the heater.