There are numerous applications where it is necessary to use a fluid to either heat or cool another. One of the most common uses of these applications is steam tracing lines, which prevent the freezing of water in pipes and valves.
A common practice has been to turn the steam on to these trace lines just prior to the first expected day where temperatures might drop below 32°F (0°C) and keep steam turned on until there is no longer any chance of seeing these freezing temperatures. During this period of time, there will be many hours where temperatures are above freezing. Significant energy reduction and cost savings can be realized if the steam is turned off during those warmer periods.
Steam is certainly not the only fluid used for heating. Hot water has been used in trace lines to control excessive heating. When using the HAT/MIX to heat water with steam it is possible to provide a closed loop Hot Water Trace System.
Glycol has been used in trace systems for winterization. HAT or TV/HAT valves placed at the end of trace lines can be used to provide the correct flow of glycol for optimum use of energy.