A heat exchanger includes a housing and a core having a shell. The shell may have an upper wall, a lower wall, and a pair of opposed side walls interconnecting the upper and lower walls to define at least part of an enclosure in which a fluid may be received. The housing may have an upper plate adjacent to the upper wall, a lower plate adjacent to the lower wall and a pair of side plates each adjacent to a separate one of the side walls. The upper plate may be connected to the lower plate and the side plates may be connected together to support the upper wall, lower wall and side walls of the shell. The support provided by the housing may, in at least some applications, permit use of a lower strength and less expensive shell.