Is the button you are resetting on top of the water heat module, underneath the combustion blower? If it is, it may be due to a failing pump on top of the heat module. This unit was noted for that. If you unit is 150,000 btu's , I feel sorry for you as the tanks only seem to last 2-4 years. They had alot of problems with the tanks leaking in the combustion chamber. The 100,000 btu heat modules seem to hold up pretty good. As far as I know they are halting production on the complete heats due to the many failures of them.