A gas powered water heater includes a storage tank, a main burner, a flame sensor assembly, and a controller communicatively coupled to the flame sensor assembly. The flame sensor assembly includes a probe positioned proximate the main burner to couple an electric current to the main burner through a flame on the main burner and not to couple an electric current to the main burner when the flame is not present on the main burner, and a detector that provides signals representative of the electric current provided through the probe. The controller is programmed to determine a length of time taken for a transition between a signal representative of no electric current and a signal representative of a steady state electric current, and determine, based at least in part on the determined length of time, a strength of the flame on the main burner.