My wife has an 11x17 room with 10' ceiling as her workshop that was built as a finished bonus room on the back side of the garage. It's built as conditioned living space but the little electric wall heater takes a long time to warm it up. I finally decided on an electric ceiling heater. I looked at a lot of heaters on Amazon and finally decided on this one:
https://www.amazon.com/dp/B0000AXEZV?psc=1&ref=ppx_yo2_dt_b_product_details
I have it set for the lowest level (2500w) and it is plenty. Had to run a 30A 240v circuit for it and ended up drilling some wiring in the wall which took a day to repair. Very pleased-The heater is quiet and smooth.