We provide the dowtherm boiler / thermal oil heater with vertical and horizontal models, vertical type reduced space and horizontal type is easy to maintenance, however, they are equally efficient in performance. The special flue design can reduce exhaust temperature, reach combustion, heat transfer of the highest efficiency, and no danger of local overheating. More, they have the same features such as system valve limit, downtherm oil temperature limit, alarm of circulation pump fail / liquid level insufficient, etc.