Pilot ON, Power to Gas Valve, No gas to burners.

dgvEP2020

Hello.
I want to see if I have diagnosed my problem correctly.
I have an American Standard G-24 series 6B-J5 boiler. The pilot was lit and when I turned it on the water pumps started working but the main burners did start up. So I turned off everything including the gas line, did some careful cleaning and tried again.
Followed instructions to relight, the pilot went on, I checked the power to the gas valve which was steady at 24v. I tried to manually start the main burners buy depressing the red manual operation button on the valve, but no gas started flowing.
Engaged the thermostat again but also no gas flowing to main burners.
Supply shouldn't be an issue since the utility upgraded our lines three years ago and so I think the Gas Valve unit has gone bad.
I just want to make sure there isn't a troubleshooting step I'm missing. I am comfortable replacing the thermocouple if that was the only problem, but if it is the Gas Valve unit I'd call a professional.
Thoughts?
Thank you.
-David

dgvEP2020

UPDATE - So I went to check it again and pushed the round brown button to the upper left of the manual start button and it jumped to life. What the hell did I press?!?

dgvEP2020

mattmia2

That's the button that opens/resets the safety valve controlled by the thermocouple.

dgvEP2020

Good to know!
So after the reset things look good so far.

EBEBRATT-Ed

If the pilot is lite then you have gas. If you have steady 24 volt power to the gas valve it sounds like a bad gas valve

EdTheHeaterMan

EBEBRATT-Ed said:

If the pilot is lite then you have gas. If you have steady 24 volt power to the gas valve it sounds like a bad gas valve

After you replace the gas valve, and you have the same problem what will you check next? Perhaps the thermocouple is weak. Try that first because it is less costly and easier to replace.

Since that gas valve is not the type with a redundant pilot included in the valve, the pilot can stay lit even if the thermocouple is bad. Very old design, and would not pass for a manufacturer to use today. Perhaps upgrading to a modern valve would be a better choice. But would you want to put money into repairing something that old?

Follow this logic and eventually be living in a new home that was custom built for you next year!

But for now, replace the thermocouple until the new home is ready.