Cleaning of ventilation ducts in ventilation systems

Brr, there are problems everywhere here...

To the OP:

Please take a look at the physical principles and also how such a ventilation system works.

Much has already been corrected.

- There is no mixing of the air.
- Dust in the supply air comes from outside
etc.

Hello everyone,

if I interpret the statements correctly, it is mainly about the problem of cleaning the ventilation PIPES.
Since these are often installed in the ceilings, it is very difficult to clean them.

In my opinion, the idea that cleaning is unnecessary is wrong.
I also cannot believe that the pipes can be cleaned with a cleaning reel including a brush and a dust trap or with a ball that is sucked through the pipe.
The pipes are way too long, and it involves fine dust.

This is what my exhaust pipes look like after 5 years.

After 4 m.

After cleaning with the new process, where a cleaning pig is pulled through the pipe.

And this is a supply air duct. Clean looks different.