PURPOSE: To provide the titled device which can reduce an energy consumption rate and emissions of pullutant, while simultaneously ensuring a delivery of hot water at a stable temperature as preset, by providing the titled device to be utilized as an auxiliary heating source and the like in a solar hot water supplying system with a control means for adjusting the capacity of burner.

CONSTITUTION: Upon a delivery port 3 being opened, a hot water is delivered from a hot water tank 4 to a hot water supplying device 11. A control means 15 detects a difference between a preset temperature and that of hot water contained in a hot water temperature detecting means 14 as the output value of burner 13 and then, in order to adjust the capacity of burner 13, the capacity of blower 16 is regulated adapted to control an air flow rate for combustion in response to the variation of fuel oil pump 17 and a fuel flow rate. In this manner, a hot water temperature to be delivered is approximated to a preset value. As mentioned above, the hot water is heated and delivered under the continuous adjustment of burner 13 so as to approximate it to an arbitrary preset value, and the resultant elimination of ON-OFF switching during operation ensures freedom from fumes and offensive smells. In addition, there is no heat emitted by scavenging and as further advantages, a stabilized delivery temperature of hot water and using convenience and the like can be obtained.