I prefer the herpstat for my rack as well, but the helix does a great job as well.
As for the helix probe, it is in the bottom section hanging right in the middle.
Thanks, you know for me it was a bit of both since I had the refrigerator already which was free in the first place, and well I love a challenge! The minimal cost was a plus of course.
I thought the same thing when putting it together but I can in fact feel the air flow all the way to the bottom. Of course that will be one of the things I will be watching closely with time, and the whole purpose of using the speed control in order to adjust accordingly. The ducting is not a bad idea though, Thanks.