A plate heat exchanger comprises first heat exchanger plates, second heat exchanger plates, first plate interspaces each formed by a primary pair of one second heat exchanger plate and an adjacent first heat exchanger plate, and second plate interspaces each formed by a secondary pair one first heat exchanger plate and an adjacent second heat exchanger plates. Each first heat exchanger plate comprises a peripheral rim surrounding a first porthole and defining an inlet channel for a first fluid through the plate heat exchanger. Each secondary pair encloses an inlet chamber adjacent to the peripheral rim. The inlet chamber is closed to the second plate interspaces, open to the inlet channel and communicates with one of the first plate interspaces via a nozzle member, thereby permitting a flow of the first fluid from the inlet channel to the first plate interspace.