Take a look at Detroit Radiant Products. Competition ( in all fairness - I'd hate to send you there! ) is Solaronics, Vantage, Reznor, among others.

I have an HL 20-75/50 in my shop, and love it. You have to be careful to not apply the first coat of epoxy within about 15 minutes after you turn the heat off - it heats the objects, not the air. So the wood continues to outgas until it's interior starts to cool.

If your shop is attached to the house, be sure whatever youre looking at is AGA rated for residential use - it's a different rating than commercial. I know we can handle that, and so can Solaronics, but I'm not sure about the others.

Another thing - dont make the mistake of thinking you can get by without insulation. Trying to heat an uninsulated space is like tossing hundred-dollar bills in the wind.

I shouldve put my work email above, it's better to ask here if you need info, I can look it up for you.