Hot water supply device, control method for same, and water treatment device

A hot water supply device, comprising:

• a water purification filter which purifies raw water;
• a heating unit into which purified water that has been filtered in the water purification filter flows, and which generates pre-heated water by heating the purified water to a first pre-heating temperature, or generates hot water by heating the purified water or reserve water, which is stored pre-heated water, to a target temperature that is higher than the first pre-heating temperature;
• a pre-heating tank in which the pre-heated water is stored as reserve water;
• a flow switching unit which switches the direction of the flow between the heating unit and the pre-heating tank;
• and
• a control unit which controls the heating unit and the flow switching unit,
• wherein in the pre-heating mode, the control unit controls the heating unit to generate the pre-heated water by heating purified water flowing from the water purification filter to the heating unit to the first pre-heating temperature, and controls the flow switching unit such that the pre-heated water generated by the heating unit is transferred to the pre-heating tank, and
• wherein in the hot water dispensing mode, the control unit controls the flow switching unit such that the reserve water flows into the heating unit, and controls the heating unit to generate the hot water by heating the reserve water flowing from the pre-heating tank to the heating unit to the target temperature.