This is what I use...it's like working under the sun...no noise, no drafts....
www.superiorradiant.com Lots of other manufactureres, too.
They come in several sizes...natural or LP gas...I have a 80K X 30 ft unit. My shop is 1500. sq. ft. with 10' ceilings in 1000 sq. ft. and a 18' ceiling in the other section.
Right now I'm closing off the high ceiling part (that's where my lift is) and will just heat my fabrication area. I'm building a sliding door that I can open to heat, and use, the other part.
The top pic is that of an RE (residential unit)..I think it comes in 30K btu and 45K btu sizes...10' long...works with low ceilings...has ONE flue hook-up for both inlet air and exhaust gas. look close and you will see the radiant tube is actually U-shaped...a total of 20' long in a ten foot section. EZ to install.
The other is a UAMA unit....available in longer sections...can be made in a 90 degree or even a U-shape.
It took us about four hours to assemble and install this heater last winter. Pretty EZ to do....safe heat as it draws outside air for combustion.