The provisions made for thermal expansion and draining of the thermal oil are key factors to consider for the successful installation of any thermal oil heating system. Important system design principles like this often are overlooked; instead, the focus is placed on specific components like pumps, valves or the heater itself.
Because most thermal fluid heating systems are closed-loop systems, and because thermal oil expands with increasing temperature, accommodations must be made for that expansion. It also is inevitable that some part of the system will require service in the future. At that point in time, the system will need to be partially or fully drained, depending upon the nature of the service required. A little thought and preplanning can make draining a system relatively easy, potentially saving time and money during planned or unplanned shutdowns.