Instant heating unit, pedestal pan and instant heating method

The invention provides an instant heating unit for heating flushing water of a pedestal pan, the instant heating unit comprises a shell with a water inlet and a water outlet, and the flushing water to be heated flows into the shell through the water inlet and flows out of the shell through the water outlet; the heating device is of a hollow tubular structure, is arranged inside the shell and extends in the longitudinal direction of the shell; an annular gap is formed between the outer surface of the heating device and the inner surface of the shell, and flushing water flows into the heating device from the water inlet, flows to the annular gap from the interior of the heating device and flows out of the water outlet through the annular gap. Due to the fact that different flows in the annular gap can form vortexes or turbulent flows, the uniformity of heating in the washing water is enhanced, and the consistency of the water temperature is improved. The invention further relates to a toilet bowl and to an inst