HOT WATER SUPPLY MACHINE

PROBLEM TO BE SOLVED: To prevent overshoot of hot water temperature when resupply of hot water is tapped in small quantity in a hot water supply machine comprising a bypass pipe which joins a hot water tapping pipe while bypassing a heat exchanger, a bypass valve provided midway of the bypass pipe and a burner for heating water through the heat exchanger, wherein the bypass valve is opened at the time of resupplying hot water. SOLUTION: A hot water supply machine comprises a circulation resistance increasing and decreasing means 14 which is provided to a water supply pipe 2 more at the side of a heat exchanger 1 than the branching point of a bypass pipe 5, or to a hot water tap pipe 4 more at the side of the heat exchanger 1 than the joining point of the bypass pipe 5, so that circulation resistance is increased when small quantity of hot water is tapped and that circulation resistance is decreased when large quantity of hot water is tapped. Thus in a condition where hot water tapping quantity is small, flow rate required at the side of the bypass pipe 5 can be secured, thereby preventing overshoot of hot water temperature and preventing excessive low temperature water from being drawn from the bypass pipe 5 at the time of large quantity tapping.