I have a Hayward H250 pool heater millivolt system, the pilot lights fine and stays on with a nice flame but I cannot get my burners to fire. My thermopile has an output of around 650 MV so that should be enough to open up the gas valve I thought. I have checked the continuity of all safety switches, they are all closed. I have jumpered each single safety/control and nothing has fired the burner. The only time I am able to fire the burner is when I jumper the TH and TH/PP terminals, but once the jumper is removed the burner shuts off along with the gas valve. I have follwed all the troubleshooting in the manual to a tea and am now on the step where it tells me to call Hayward Technical Service. Thought I'd just hop on here and see if anyone has any suggestions. I have heard that small amounts of dirt, or corroded contacts could be the source of the problem since the voltage is so small going through each component but I cleaned everything up and am still at the same spot.
Any help would be appreciated