The 4838 Temperature Controller is designed to control the temperature in our far reaching line of non-blended pressure vessels. No procurement is made for the current or future extension to control engine mixing speeds or activate cooling water. The 4838 Controller could be improved with the expansion of either a Pressure Display Module or a High Temperature Cut Off Module or an External Temperature Limit Module. The 4838 holds the same Temperature Control Module utilized within the 4848 Controller and gives indistinguishable control and interchanges abilities. The high low heater feature (full or half power) and the lock out relay and reset for over temperature assurance are additionally included.