Abstract: A versatile heater/cooler (2) comprising a chest (4) having insulated walls (6, 8, 10, 12, 14) including a lid (10). Contained within the chest is a removable heating and cooling source (46) which is submersible in a liquid for heating or cooling the latter. The source comprises first and second vertical conduits (48, 50) having lower portions connected for fluid communication with a transverse body (52) which forms a combustion chamber. The chamber serves for burning fuel (80) or for containing a refrigerant introduced by way of the conduits. Included in the chest lid is a vent port (110) for venting the chest contents including the source, and two limb ports (18, 20) for inserting the limbs of a user through the ports and into the interior of the chest. A self-adjusting shield (22, 24) connected to an edge portion of each limb port, yieldingly surrounds each limb for preventing hot or cold air losses from the chest.