Condensing heat exchanger and water heater having same

A condensing heat exchanger, comprising:

• a heat exchanger housing having a flue gas inlet and a flue gas outlet;
• and
• a heat exchange unit located within the heat exchanger housing,
• wherein a sidewall flue gas exhaust channel communicated with the flue gas outlet is provided between the heat exchange unit and an inner sidewall of the heat exchanger housing, the heat exchange unit surrounds a flue gas inlet channel communicated with the flue gas inlet, the sidewall flue gas exhaust channel surrounds the heat exchange unit, and the heat exchange unit is internally provided with a heat exchange flue which communicates the flue gas inlet channel with the sidewall flue gas exhaust channel, and
• wherein the heat exchange unit comprises a plurality of heat exchange tube layers stacked in a vertical direction, the heat exchange tube layers comprise a plurality of heat exchange tube rings nested with one another and having surrounded areas gradually decreasing from outside to inside in a radial direction, and the heat exchange flue comprises a spacing flue located between adjacent two of the heat exchange tube layers in an up-down direction.