Subwoofer tuning

If I have a down firing HSU 12V sub and I want to place it on my sweet chair in a new home when we move, can I set it on the couch firing upward while listening to the room? or is it best to maintain its down fire profile? If that is the case I will only be able to put it on floor in same spot as chair would be, but ultimatly I thought it would be best to have sub at ear level unless I am mistaken, any thoughts please?
In my experience, the positioning of the sub close to the chair, or sitting in the chair with the sub firing sideways will be fine. The wavelengths are so long, unlike the high frequencies. I wanted to set my VTF-3R in my seat, but at 80 pounds, I would either hurt my back or drop the sub! I believe that the direction it fires is only important if it is aimed at a wall or a corner where the frequencies will multiply.
thank for your reply