A device for heating or cooling multiple single chamber containers or a multi-chamber container. The device includes: a unitary heat or cold source providing a source of heat or cold; heat exchange elements in thermal communication with the heat or cold source and extending away from the heat or cold source; a thermal barrier between each of said heat exchange elements to thermally isolate the heat exchange elements from each other. Each heat exchange element is thermally associated with one or more chambers that are different from one or more chambers associated with other heat exchange elements to thermally isolate the chambers from each other. Preferably the container is a sample or reagent container used in a clinical analyzer, such as a multi-chamber reaction cuvette or a multi-chamber microtiter plate. An incubator assembly, preferably usable in a clinical analyzer, can include the device for heating or cooling.