RE: heating a patio room. I recommend using a ceiling mounted electric radiant heat panel from Solid State Heating Inc Old Saybrook CT (www.sshcinc.com) 800-544-5182 I used a 2'x4' x 1" 110 volt panel in my window seat/bed and it works very well. You can feel the heat "bouncing" off the glass. I liked the panels so well I put a 2'x6' 220 volt panel in my bathroom.. toasty. I am currently installing several panels in the basement "guest" room. They mount flush with the ceiling and use " wire mold" to run the wiring to the outlet. Hard wired is best but I used a plug and an outlet for the porch.
No fans, no blowers, filters, non allergenic, just long wave infrared heat.