Laars MT2V 0500 Mighty Therm2 Commercial Boiler and Volume Water Heater The Mighty Therm2 has been specifically designed to meet the needs of the replacement market by offering simple and straightforward controls with 2-stage firing and 85% thermal efficiency.Mighty Therm2 boilers and water heaters feature convenient, modular construction that separates the burner trays, gas train, and blower assembly. All models use lightweight insulation, glass-lined cast iron or bronze headers, and non-ferrous waterways. The 10 tube heat exchanger design uses finned tubing for the quickest and most efficient heat transfer.