Air conditioners are installations to create and maintain a steady temperature, humidity, as well as a requested air quality in inner rooms. In tropical and subtropical countries, the term air conditioning mostly stands for installations which cool the air down to a preset temperature. There, they are often a condition for a quality of life and performance in inner rooms, as it is usually found in countries of temperateness. Air-conditioned inner rooms are a necessity in many warm countries in order to build and maintain competitive industries as well as tourism.

Ventilation systems are devices used to supply housing and business rooms as well as industrial installations with outer air, or, to derive contaminated inner room air. Depending on their application, these devices transport controlled supply or exhaust air, or both at the same time.

Air conditioners as well as ventilation systems, depending on their conception and size, can be equipped with channels which extend over many meters in a building in the most different diameters, in round and/or angularly shape.

The economicalness and hygiene of a carefully conceived inner room air technological installation is only granted in case of thorough cleaning of the entire system. Deposits of dirt on the fans and in the ducts e.g. reduce the air flow and therefore the economicalness of the installation. If dampness develops in the polluted ducts due to climatic conditions, bacteria, mold and micro-organisms can spread very fast and in large quantities. In case they and their components get into the breathing air, the users of such microbiologically contaminated devices are endangered, and severe health damage may occur.

Since people can not only be effected in their private environment, but also in many offices, places of production, hotels, banks, stores, hospitals, etc., where inner room air technological installations are in use, health damages due to a lack of maintenance do not only mean reduced quality of life, but also reduced ability to perform. The term "sick building syndrome" is often put in relation to this. A downgrade of inner rooms or even complete buildings contaminated this way is often the consequence.

Whether it concerns old or new devices installed according to the most state-of-the-art requirements, depending on the conception and use, cleaning in certain intervals is necessary in order to keep up the economy and hygiene. In some countries, precise regulations and guidelines have been compiled for this, such as VDI 6022 in Germany.