Greg is right, the Royal/Dirt Devil central vacuums are private labeled Vacuflo filtered cyclonic units. However, I MUCH prefer the Vacuflo "true cyclonic" units (which are dark blue in color and only available under the Vacuflo brand)...the cartridge filters on the FC units are difficult to completely clean, and the very fine dust that can (and does) get by the seals on the filter causes the motor to run louder and louder over time. I sold quite a few of the Vacuflo filtered cyclonic units due to their great performance specs and quicker installation (no outside exhaust needed) but have shied away due to the issues above, which I've seen time and again. Hayden central vacuums rely on the same principle and have the same issues. If you want a bagless central vacuum, the Vacuflo true cyclonic is worth the extra 15 minutes to chisel a hole in the wall (assuming you have brick, rather than siding) and vent it outside.
For a bagged central vacuum, the cleanest and easiest to empty are the ones with a "closed" bag...NuTone, Cyclovac, Drainvac, etc. However, these also lose their performance the most quickly, as the bag sits in a bucket with the inlet on top, and the suction coming from above. Meaning that only a small amount of the bag's surface area is exposed to airflow, the majority just glues itself to the sides of the bucket. The genius of the MD Silentmaster/Filtex/CVI design is that the bag is inside a cloth bag, suspended by the rim with the motor(s) below, so the entire surface area of the bag is exposed to airflow. You can tell a BIG difference as the bag fills; the open bag design keeps the air flowing longer. A little messier to empty, but nowhere near as bad as a bagless system, with or without a filter.
I really have to take issue with vacu-finder's comment that most central vacuums are the same, just a "can with a motor"...my experience having sold, serviced, installed and owned most every central vacuum system out there shows that to be completely untrue, for the reasons outlined above and many more.
Scott, I hope this helps. If you're looking for more information, you could check out my blog at http://jcvacs.blogspot.com or contact me by email, operkins@justcentralvacs.com
Best regards,
Owen Perkins
