WATER HEATING APPARATUS
A water heating apparatus includes: an exhaust gas passage through which an exhaust gas from a burner flows; a water flow passage through which water flows; a first heat exchanger configured to exchange heat between sensible heat contained in the exhaust gas and water flowing through a heat exchanger tube, and arranged at upstream side of the exhaust gas passage and downstream side of the water flow passage; a second heat exchanger configured to exchange heat between latent heat contained in the exhaust gas and water flowing through a heat exchanger tube, and arranged at downstream side of the exhaust gas passage and upstream side of the water flow passage; and a bypass pipe arranged in the water flow passage in such a position as to bypass the second heat exchanger and designed to allow a at least the predetermined minimum amount of water required for a burner combustion operation to flow therethrough into the first heat exchanger.
1 . A water heating apparatus comprising:
an exhaust gas passage through which an exhaust gas from a burner flows;
a water flow passage through which water flows;
a first heat exchanger configured to exchange heat between sensible heat contained in the exhaust gas and water flowing through a heat exchanger tube, and arranged at upstream side of the exhaust gas passage and downstream side of the water flow passage;
a second heat exchanger configured to exchange heat between latent heat contained in the exhaust gas and water flowing through a heat exchanger tube, and arranged downstream of the exhaust gas passage and upstream of the water flow passage; and
a bypass pipe arranged in the water flow passage in such a position as to bypass the second heat exchanger and designed to allow at least a predetermined minimum amount of water required for a burner combustion operation to flow therethrough into the first heat exchanger.
2 . The water heating apparatus according to claim 1 , wherein a water drain pipe is connected in the water flow passage at an intermediate portion between the second heat exchanger and the first heat exchanger, and the bypass pipe is connected between an upstream side of the second heat exchanger and the water drain pipe, in an up-and-down direction.
3 . The water heating apparatus according to claim 1 , wherein at least at a downstream end of the bypass pipe, the bypass pipe has an inner diameter to allow the predetermined minimum amount of water to flow therethrough.
4 . The water heating apparatus according to claim 2 , wherein at least at a downstream end of the bypass pipe, the bypass pipe has an inner diameter to allow the predetermined minimum amount of water to flow therethrough.