With the FDR humidity difference control, Helios has developed new systems that automatically ensure optimum room humidity and thus provide a lasting solution to problems with damp rooms. FDR is available in two variants - one for applications in smaller rooms such as single-family house cellars and a solution for larger air volumes that can also be individually assembled for the requirements of industry and commerce. The systems continuously measure temperature and humidity inside and outside. The intelligent control then decides whether suitable conditions for ventilation are present, so that optimal functioning is always guaranteed.