PROBLEM TO BE SOLVED: To easily suppress an abnormal water temperature rise at a channel 24 when the water flow level through the channel 24 is decreased.SOLUTION: An exterior temperature controller for a water tank is provided, being such that, a flow level sensor 51 is installed at the channel 24 on an exhaust port 32 side off a heater 38 when a flow level detected by the sensor 51 comes to a predetermined value or lower, there is installed a second control unit 54 functioning to lower the calorific value of the heater 38 based on a detection result given from the sensor 51 therefore, when the level of water flowing the channel 24 is lowered below a predetermined value due to filtering materials cloggings, a pumps trouble, or the like, the second control unit 54 works so as to lower the calorific value of the heater 38 as a result, an abnormal rise in the temperature of water W flowing through the channel 24 is easily suppressed, enabling other instrumentss troubles and empty heating to be inhibited.COPYRIGHT: (C)2010,JPO&INPIT【課題】通路24を流れる水量が減少したとき、通路24における水温の異常上昇を容易に抑制する。【解決手段】ヒーター38より排出口32側の通路24に流量センサ51を設置するとともに、前記流量センサ51によって検出された流量が所定値以下となったとき、流量センサ51からの検出結果に基づいてヒーター38の発熱量を低下させる第2制御部54を設けたので、濾過材の詰まり、ポンプの故障等により通路24を流れる水の流量が所定値以下まで減少すると、第2制御部54がヒーター38の発熱量を低下させる。この結果、通路24を流れる水Wの温度の異常上昇が容易に抑制され、他の機器の故障や空焚きを抑制することができる。【選択図】図2
