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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My elderly G12 - pilot is lit, but the main valve turns on

Customer Question

My elderly G12 - pilot is lit, but the main valve turns on for a few seconds then shuts down.
JA: I'll do all I can to help. How long have you been dealing with this?
Customer: This year
JA: Do you plan on doing the work yourself?
Customer: Yes
JA: Anything else we should know to help you best?
Customer: It's a continuous pilot lit operation, not a spark ignition
Submitted: 9 months ago.
Category: HVAC
Expert:  Phil replied 9 months ago.

Hello, I need the brand name of the water heater or furnace and its model number.... or a photo of the units wiring diagram glued to the inside of the blower service panel if its a furnace.

I need the brand name and model number on the gas valve as well, I also need to know if there is a knob or lever on marked ON-OFF-Pilot or not.

So far it sounds like a bad thermocouple or flame sensor problem, an easy fix in most cases.