HOT WATER STORAGE TYPE HOT WATER SUPPLY SYSTEM

PROBLEM TO BE SOLVED: To achieve measurement accuracy improvement and cost reduction by allowing a flow rate sensor for detecting a drainage flow rate to be arranged in a low temperature part.SOLUTION: A drainage necessity determination unit 22 determines whether or not it is necessary to drain hot water in a hot water storage tank 1. When it is determined that drainage is necessary, a drainage control unit 23 prohibits hot water supply from the hot water storage tank 1 by a closing operation of a hot water supply path opening/closing valve 5, drains the hot water in the hot water storage tank 1 by an opening operation of a drainage path opening/closing valve 13, and performs water supply to the hot water storage tank 1 accompanying the drainage, as drainage processing. A flow rate sensor 18 is provided in a tank supply water path 10. A drainage termination determination unit 24 terminates the drainage processing when an integrated value of detection water supply flow rate by the flow rate sensor 18 after start of the drainage processing has become equal to or more than a predetermined value corresponding to tank capacity. 【課題】 排水流量を検出する流量センサを低温部に配置できるようにして、測定精度向上、コスト低減を図る。【解決手段】 排水要否判定部２２は、貯湯タンク１内の湯水を排水する必要があるかを否かを判定する。排水制御部２３は、排水が必要であると判定されたときに、排水処理として、給湯経路開閉弁５の閉操作による貯湯タンク１からの給湯の禁止、排水経路開閉弁１３の開操作による貯湯タンク１内の湯水の排水、及び、排水に伴う貯湯タンク１内への給水を行う。タンク給水経路１０には流量センサ１８が設けられる。排水終了判定部２４は、排水処理の開始後の流量センサ１８による検出給水流量の積算値がタンク容量相当の所定値以上になったときに、排水処理を終了させる。【選択図】 図１