Cats are vortex hunters, so for them it is easy to find one. Steven Gibbs says if you have an HDR get a cat to help you. Basically, the cat can find a vortex that is open. These usually have a chemical smell similar to chlorine or ammonia. Chlorine smells like pool water and ammonia is similar to wet diaper aroma. Hey, very unpleasant and then some more. That said, I believe that you cannot use an HDR with out a vortex that is open. OK, so get a cat to help you.
