Abstract: A closed heat transfer system which is capable of providing more efficient heat transfer by virtue of the fact that a small fuel burner is operated for a longer period of time but with much less consumption of fuel than compared to a conventional cycled heating system. The system includes a heat sink containing a suitable heat storage fluid, a heat source, heat transfer means, a preheater means, hot water feed means, and circulator means. The heat sink preferably takes the form of a closed container operable in the manner of a boiler and filled with a suitable heat storage fluid.