The Chem-Dry version of the RX 20 is called the powerhead . It differs from the normal RX20 in that the vac slots are "optimized" load of hype to extract an extra grand out of franchissees , they even said it was patented. Instead of one vac slot , there were a series of holes whick they claimed amplified the vacuum power. It had 2 solution inputs so that the A and B solutions could mix and carbonate just before hitting the carpet, causing a "violent explosion of soiling in the carpet being cleaned" ---Quotes are what was actual wording of the newsletters.
Originally they were hooked up to the single vac ,100 psi pumped "Velda" machine, a £6 grand portable (in 1996).
Now they have the option to hook up to an adapted HM truckmount, which still only has a low powered pump on it.
I have since used a normal RX20 hooked up to a TM and they work great , I would rather ise one than a wand.