A vat system comprising: a vat that includes a bottom wall and side walls extending upwardly from the bottom wall and a heat exchanger (70) provided in at least one of the bottom and walls. The heat exchanger includes a pair of sheets (71, 72) with at least parts of the sheets being spaced from each other and defining a void space (105) therebetween and being configured to convey a heat transfer fluid therethrough. A baffle extends between and connects the sheets to each other. At least part of the baffle is spaced inwardly from an outer periphery of the heat exchanger and directs flow of the heat transfer fluid through the void space. Multiple posts (95) extend between the sheets and are spaced from the baffle so that the heat transfer fluid flows around the multiple posts when being directed through the heat exchanger by the baffles.
