A perfect alternative to the electric 40 gallon tank water heater. Provides endless hot water for 1 major application at a time. 95% efficiency rating. 10 year warranty on heater, 1 year warranty on parts for both commercial and residential use. Solid copper heat exchanger. External temperature control knob. Thermal cut-out for safety. Flow sensor to provide a constant output temperature. Electronic flow switch. No temperature/pressure relief valve necessary (check local codes). Filter screen on inlet. UL approved. Model No. AE115 not recommended in climates where average ground water temperature is less tha 60 F. No. AE-115: Ground water is greater than 60 No. AE-125: Ground water is less than 60