Product review (5 stars): works great!
I bought this unit few months ago. The contractor installed it. initially, the unit didn't work properly.  The identified problems were [1] unit vibrates [2] no suction power. I was advised by Amazon community that there could be obstruction.  I called the contractor again, he has changed the piping from 6 inch to 8 inch. The contractor used flex and metal piping since 35-40 feet long he had to run the pipe. That could be the reason 6 inch did not work. Now the unit is quiet, works great!