Gas Valve - 24V. ??

[Louis F]

Does the 24Vac stay powered at 24volts while the device is on?

My gas valve generates 24V at the ignition point, then drops back to millivolts.  

I am not sure if I need to replace the fenwal board.

You’re assistance would be greatly appreciated.   

Backround:  Pool heater,  it ignites with an overcombustion pop and goes out.   Shows an ignition error.  I tested the voltage to the gas valve and it get 24v at the ignition point… that sustains for about 2 seconds,  then it goes back to milli volts.    I am replacing the gas value in any event… but think it may well be the fenwal board that needs replacement.