| 摘要 |
PURPOSE:To reduce the immersion depth of a combustion cylinder by providing a preheating water tank wherein a liquid being not yet heated by a direct-heating water tank is preheated by cobustion gas which has passed through the liquid in the direct-heating water tank. CONSTITUTION:The lower end part of a closed housing 1 serves as the preheating water tank 1A, in which is placed a preheating heat exchanger 3. The upper end of the heat exchanger 3 is opened 3A above the water surface, while the lower end is communicated with an exhaust cylinder 4 outside of the housing 1. The direct- heating water tank 5 at the upper part of the housing 1 is connected with the tank 1A by a water feed pipe 6, which is provided therein with a water feed pump 7. The tank 5 is provided with a water-level detector 8 for controlling the pump 7, a hot-water discharge port 9 and an exhaust port 10 for combustion exhaust gas. The combustion cylinder 11 provided with a fuel supply pipe 12, an air supply pipe 13 and a burner 15 is extended downward from the top of the housing 1 into the tank 5. |
