| 摘要 |
PURPOSE:To perform accurate freeze prevention by providing a low temperature operating valve on the upstream side of a heat exchanger at a position spaced from the pipeline connected part, and a bypass passage so that at the time of actuating the low temperature operating valve, water is flowed from the bypass via the heat exchanger. CONSTITUTION:The low-temperature operating valve 12 which begins to exhaust water when the temperature becomes less than a predetermined temperature is provided on the upstream side of a heat exchanger 7 and at a position sufficiently spaced from a pipeline part heater such as an electric heater band (not shown) or the like, and a quantitative opening valve 20 is provided on the upstream side of the valve 12. Further, a bypass passage having a quantitative closing valve is provided on the upstream side, and is connected to the water passage 4 on the downstream side of the heat exchanger 7. Upon carrying out exhaustion of water when the low temperature operating valve 12 is actuated, water is passed in the order of bypass passage heat exchanger to low-temperature operating valve 12. By this mechanism, the low-temperature operating valve can perform accurate freeze prevention without any erroneous operation by an electric heater band or the like. |
