Abstract: The device concerns among other things a plate heat exchanger having at least one pile of plate elements, each of which plate elements has a central heat transferring part and an edge part (15) surrounding this part, the heat transferring parts of the plate elements delimiting flow spaces between one another for at least one heat exchanging fluid (F1) and every plate element being of a double wall construction and having two heat transferring plates (1, 5; 2, 6; 3, 7; 4, 8) with a space therebetween. At least one layer element (16) is present in the space between the heat transferring plates (1,5; 2,6; 3,7; 4, 8) in at least one of the plate elements, every layer element (16) having at least one electrical connected resistive layer making electrical heating of the layer element (16) possible.