RESOL controllers include a built-in control process optimization algorithm.  This optimization is based on custom setup options - so the installer should learn to recognize and use these features effectively.

One of the Special Functions for control optimization is OTC - Tube Collector Special Function.

I'd like call it a control optimization function for special Tube collectors. You see, the introduction of direct flow (Sydney type) vacuum tube collectors has made possible to mount collectors horizontally on flat roofs. The U-shaped tubing inside the vacuum tube conducts media to common headers. The heat produced in the tube will not freely rise to the sensor well if the collector is installed horizontally. The resulting delay in the temperature readings necessary to start the circulator could create a problem, especially for systems with large collector arrays.

But this will not happen with the RESOL controller , my friends! The use of OTC function for that application will do the trick.