| 摘要 |
<p>PURPOSE:To enable additional heating surely and economically corresponding to volume of hot water to be used by a method wherein apart from a main heating using a lower heat generator, additional heating is made by using an upper heat generator or the lower heat generator. CONSTITUTION:In order to give priority to an additional heating at are times, temperature of hot water above an upper heat generator H2 is confirmed to determine whether or not additional heating conditions are satisfied. In the case that with a first and a second temperature sensor TS1 and TS2, additional heating starting conditions are satisfied, a power supply passage switching means 5 switches a power supply passage to an upper heat generator H2 side to start power supply. A switch SW1 in the power supply passage switching means 5 is in contact with a terminal t2 while another switch SW2 is open. When the additional heating conditions are satisfied, the power supply to the upper heat generator H2 is interrupted, and the power supply passage is switched to a lower heat generator H1 side. In this state, a movable contact of the switch SW1 is in contact with a terminal t1 while the switch SW2 is open. Next, it is determined whether an additional heating command or an extra heating command is given.</p> |
