Instant Heating Unit, Toilet and Instant Heating Method

The present invention provides an instant heating unit for heating washing water of a toilet, the instant heating unit comprising: a housing having a water inlet and a water outlet, washing water to be heated flowing into the housing through the water inlet and flowing out of the housing through the water outlet; and a heating device, the heating device being configured to be of a hollow tube shape, arranged inside the housing, and extending along the longitudinal direction of the housing; wherein an annular gap is formed between the outer surface of the heating device and the inner surface of the housing, the washing water flows into the interior of the heating device from the water inlet, flows from the interior of the heating device to the annular gap, and flows out of the water outlet through the annular gap. Due to different flows in the annular gap, vortexes or turbulent flows can be formed, so as to enhance the uniformity of heating inside the washing water and improve the consistency of the water temperature. The present invention further relates to a toilet and an instant heating method for heating washing water of a toilet by means of an instant heating unit.