Heater info needed as winter approaches

[1kathleen]

I am adding to my greenhouse which will be 6 by 26 feet now - leans up on side of house and up on a deck because of flooding here - In the past I have used small space heater or two when it gets very cold for a 6X12 area - now that won't work. Vented gas seemed very questionable and pricey to get here - Lg 220 heater would require wiring and new fuse box which I would rather not use so I found a portable heat pump/air conditioner 13,000 BTU's in a gardening catalog that sells greenhouses. I couldn't tell who makes the unit and it is supposed to be something new. Does anyone know anything about these units? What do you use in a space this size? It is triple wall poly carb.Thanks so much for your help..k