Abstract: There is disclosed a method for continuously monitoring temperature at multiple locations within a controlled temperature unit (CTU) using RTDs that can be removed and reinserted. The key to the method is the collection of data using an RTD fixed in a phenolic thermowell, which in turn is inserted through a polytetrafluoroethylene-coated sleeve in the wall of the CTU. The temperature information is transmitted from a data module to an interfaced computer system where it may be presented to the operator in a graphical, tabular or text format or stored in memory. The temperature probes are easily removable so as to facilitate calibration without disruption of the contents of the CTU and can be consistently replaced in the same location within the CTU.