Gas valve voltage

  • Last Post 06 January 2021
Scrappy posted this 04 January 2021

Raypak 406A propane pool heater will not light.  Error code Ignition Lockout and Pilot not sense.  When checking voltage to the gas valve with a voltmeter, is it normal for the voltage to jump around when the unit is sparking?  In between sparking the voltage at the gas valve reads 28VAC.  Gas pressure has been checked to the valve and is ok.  No gas is coming through the valve and trying to exactly determine if it is the valve or the PC board.  Thanks!

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InyoRob posted this 04 January 2021

Assuming that the tank is at least half full, 28VAC at the pilot valve should allow gas to flow to the pilot and ignite the spark.

First, visually confirm that the pilot is not lighting.

If not, and there is 24+VAC at the pilot valve (red/black wire); then we need to CAREFULLY determine is gas is exiting the valve:

Turn the power, to the unit, OFF.

Disconnect the pilot tube from the gas valve.

Turn the heater back on.

While the ignitor is sparking, check to see if gas is exiting the valve where the pilot tube was connected.

QUICKLY, turn OFF power, and ventilate the area in and around the bottom of the heater.

If gas was NOT coming out of valve, with the unit sparking and 24+VAC present, then all points to the pilot solenoid on the gas valve. Replace gas valve.


If gas was present, but pilot wouldn’t light, then thoroughly clean the pilot tube. If pilot still doesn’t light, clean or replace the pilot.


If the pilot DOES light, but is not sensed by the board:

Check the green ground wire that goes from the pilot bracket up to the valve and from there up to the board. Make sure ground is sound and tight, as the sensing signal travels the ground from the pilot to the PC Board.

Confirm that the pilot is free of debris, or corrosion. If corroded, replace pilot.


If the pilot is lighting, and all else checks out. Replace PC Board.


Hope this helps.

Scrappy posted this 05 January 2021

Thank you for that great advice!  Gas is not coming out of the pilot port on the gas valve when unit is sparking and trying to light.  The pilot never lights and there is no signs of gas.  The only question I have is measuring the 24VAC to the valve, is it normal for the voltage to jump all over the place when the unit is sparking?  Or should it always be a steady voltage measurement of 24VAC?  In between sparking, the voltage measured at the valve on terminals PV-PV/MV is 28VAC.

InyoRob posted this 05 January 2021

The voltage should remain steady. Double-check the wire connection on both ends of the red/black wire that runs from the PCB down to the gas valve. Re crimp with a new spade connector if needed.

Scrappy posted this 05 January 2021

Measuring the pins that come out of the PC board I get the same results, with the voltage jumping all over the place while the unit is sparking.  In between sparks, the voltage is steady at 28VAC.  Does this mean the PC board is bad?   Thanks!

InyoRob posted this 06 January 2021

With that being the case, then it sounds as if there is a short in the board’s ignition microprocessor and needs to be replaced. So yes, we recommend replacing the board.

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  • Scrappy
Scrappy posted this 06 January 2021

Thank you InyoRob, appreciate the help on this!!

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  • InyoRob
InyoRob posted this 06 January 2021

You're welcome. Good luck!