In a field-installable refrigerated merchandiser kit, a prefabricated refrigeration system module releasably and operatively connects to a separate cabinet module via mutual connection fittings to form a refrigerated merchandiser. The refrigerated merchandiser can have multiple refrigeration systems cooling a common refrigerated space inside the cabinet, each with an independent temperature controller. A refrigeration system can be disconnected from the cabinet only by separating releasable fasteners and disconnecting electrical plug-in connections. Each refrigeration system is prefabricated with integrated condensate removal. The refrigeration system mounts entirely above the top wall of the cabinet enabling deployment at zero offset from a backing structure. The refrigerated merchandiser can be deployed to occupy a footprint and have a ratio of shelf space volume to foot print greater than 3.25 ft3/ft2.