HEAT SOURCE DEVICE

PROBLEM TO BE SOLVED: To supply hot water at a stable hot water supply temperature, even when heating operation is performed on the side of a water heater which supplies hot water without heating by feeding the hot water from a hot water storage tub to the water heater, for example.SOLUTION: A heat source device is configured to have: a hot water supply additional heating function for heating by a hot water supply heat exchanger in an appliance case in a water heater, and supplying, hot water fed to the water heater from a hot water storage tub; and a hot water supply non-additional heating function for supplying hot water fed to the water heater without heating. A heating heat exchanger for heating a heat medium which is supplied to a heating device from the water heater is provided in the appliance case in the water heater. When an air supply/exhaust fan 65 is driven at the time of heating by a burner of the heating heat exchanger, additional hot water supply control means 39 enables the temperature of hot water which is fed from the hot water storage tub 2 to the water heater 16 to be higher than the temperature of a predetermined hot water supply set temperature by a predetermined additional temperature. 【課題】例えば貯湯槽からの湯を給湯器に通して給湯器では加熱せずに給湯する場合に給湯器側で暖房運転が行われても安定した給湯温度で給湯する。【解決手段】貯湯槽から給湯器に導入される湯を、給湯器の器具ケース内の給湯熱交換器により加熱して給湯する追い加熱給湯機能と、給湯器に導入される湯を加熱せずに給湯する非追い加熱給湯機能とを有する構成とする。給湯器の器具ケース内には、給湯器から暖房装置に供給する熱媒体加熱用の暖房用熱交換器を設け、暖房用熱交換器のバーナによる加熱時に給排気用のファン６５が駆動されたときには、暖房時下駄上げ出湯制御手段３９が貯湯槽２側から給湯器１６側に送られる湯の温度を予め定められる給湯設定温度よりも予め定められる下駄上げ温度高い温度とする。【選択図】図１