The HECR is a refrigerant-free temperature control device mountable in a 19-inch rack. Rack mounting recovers desktop or floor space, permitting stacking of related devices and mobility, depending on the rack style. Air cooling frees the installation from dependence on facility cooling water. This model achieves high precision regulation of recirculating coolant using an air-cooled peltier element. This device is self-contained with peltier regulating element, fan cooled heat exchanger, pump, tank and power supply.