Patent ID: 6971335

Claim:
A water heater comprising: a burner for burning fuel gas in a combustion chamber; a main heat exchanger which recovers sensible heat from exhaust gas discharged from the burner to heat flowing water in a heat transfer tube; a secondary heat exchanger which recovers sensible heat which has not been recovered in the main heat exchanger along with latent heat from the exhaust gas which is passing through the main heat exchanger to heat the flowing water in the heat transfer tube, and a drain evaporator which heats and evaporates drain generated by recovery of the latent heat in the secondary heat exchanger, wherein a route of the exhaust gas which is passing through the main heat exchanger is divided into a first exhaust route and a second exhaust route, and the secondary heat exchanger is provided with the first exhaust route and the drain evaporator is provided with the second exhaust route.