The invention relates to a plate-type heat exchanger (20) comprising a stack (21) of heat exchanger plates which are permanently interconnected and between which separate flow passage spaces are defined for at least two heat exchange fluids. One part of the heat exchanger plates is designed as single-walled heat exchanger plates each, having one plate member, while another part of the heat exchanger plates is designed as double-walled heat exchanger plates each, having two plate members.