Justasanging,
We have a 8x10 walk in closet in our master bedroom which has a air vent in it from HVAC system. 9' cieling.
Right above that air vent I have a couple of window screens setup so they are resting from corner to corner on some high shelves we have built in there.
After washing mine and letting it dry for a bit on a towl (a couple hours usually) I lay it out on those window screens in a thin layer - not really touching and just leave it for 3 weeks or so, possibly more.
When I start running out of space I check and find all the ones that are good and dry and put them over in a cardboard box that sits on that shelf.
Smaller roots will be good and dry in 3 weeks, larger fat roots may take a week or two longer.
Again this is HVAC system air space and has good air circulation (no moisture issues).
I don't rush it at all, no heat, and it drys just fine with a little time.
If I needed to dry it faster for some reason (like I had to sell some early for some reason) I would do as the others have suggested, apply a moderate amount of heat and increase the air circulation with forced air/fan.
Good Luck !
TNhunter