I have a Hampton H15 gas direct vent stove. It has been working for several years on a thermostat. The first time this year, everything worked, piolt, gas, flame..ect, except it wouldn't shut off. I disconnected the themostat completely the stove was still on. Only disconnecting the thermopile shuts it of. As soon as I connect the themopile to contacts on the stove valve, I hear the click and the gas valve opens and there is a flame without the thermostat connected. The gas valve is a 910-478 S.I.T on natural gas. Does the whole gas valve assembly need to be replaced? I didn't think the thermopile could directly open the gas valve, I thought it would generate a millivolt level power for the thermostat control. I guess I don't know how a gas valve works?