HEAT EXCHANGER, REFRIGERANT CYCLE DEVICE AND WATER HEATER

To provide a heat exchanger capable of securing heat exchanging performance even if two fluids have a difference in pressure when flowing in, and a refrigerant cycle device and a water heater using the same.SOLUTION: A first heat exchanger 100 comprises a first heat conduction plate 110 and a second heat conduction plate 120. The second heat conduction plate has second flow ports 121a, 121b, second through holes 122a, 122b, a second heat conduction region 123, and second connection parts 125a, 125b. The second flow port introduces and delivers a second fluid having a lower boiling point than a first fluid. The second through hole allows the first fluid to pass through in a thickness direction. In the second heat conduction region, the second fluid exchanges heat with the first fluid while passing through it. A second connection part has one end connected to the second flow port and the other end connected to the second heat conduction region. The second flow port is formed at a position on the opposite side from the second heat conduction region across the second through hole. The second connection part is formed bypassing the second through hole outside, and is provided with second projection parts 127a, 127b.SELECTED DRAWING: Figure 7 【課題】２つの流体の流入時のおける圧力に差がある場合でも、熱交換性能を確保できる熱交換器、並びにこれを用いた冷媒サイクル装置及び給湯器を提供する。【解決手段】第１熱交換器１００は、第１伝熱プレート１１０と、第２伝熱プレート１２０とを備える。第２伝熱プレートは、第２流通口１２１ａ、１２１ｂと、第２貫通孔１２２ａ、１２２ｂと、第２伝熱領域１２３と、第２接続部１２５ａ、１２５ｂとを有する。第２流通口は、第１流体よりも低沸点である第２流体を導入・導出する。第２貫通孔は、第１流体が厚み方向に通過する。第２伝熱領域では、第２流体が通過しながら第１流体と熱交換をする。第２接続部は、一端が第２流通口に、他端が第２伝熱領域に接続される。第２流通口は、第２貫通孔を挟んで第２伝熱領域と反対の位置に形成される。第２接続部は、第２貫通孔の外方を回り込むように形成され、第２突起部１２７ａ、１２７ｂが設けられる。【選択図】図７