Abstract: A fluid heat exchange system with a fluid flow circuit having a heat exchange fluid flow loop, a heat absorption component (as in a domestic hot water tank inclusive of small commercial use tanks as in tanks of 20 to 120 gallons), a heat exchanger and preferably also a pump. A controlled and automated fuel supply source based heater (as in a pellet stove) is in heat passage communication with the said heat exchanger. A control unit triggers activation of the pump upon fluid in the heat absorption component reaching or dropping below a preset temperature, and the fluid flow circuit is arranged such that, during times of non-activation of the pump, fluid is free to flow in a unidirectional flow within the fluid circuit based on thermodynamic temperature differentials alone. A retrofitting of a domestic hot water tank is also featured preferably making use of preexisting drain and safety vent porting for in-feed and out-feed porting in the exchange loop side.

Abstract: A fluid heat exchange system with a fluid flow circuit having a heat exchange fluid flow loop, a heat absorption component (as in a domestic hot water tank inclusive of small commercial use tanks as in tanks of 20 to 120 gallons), a heat exchanger and preferably also a pump. A controlled and automated fuel supply source based heater (as in a pellet stove) is in heat passage communication with the said heat exchanger. A control unit triggers activation of the pump upon fluid in the heat absorption component reaching or dropping below a preset temperature, and the fluid flow circuit is arranged such that, during times of non-activation of the pump, fluid is free to flow in a unidirectional flow within the fluid circuit based on thermodynamic temperature differentials alone. A retrofitting of a domestic hot water tank is also featured preferably making use of preexisting drain and safety vent porting for in-feed and out-feed porting in the exchange loop side.