Unless its a real small and very well insulated shop???? a 5000 watt electric heater, especially one hanging up in the air, isnt a whole lot of heat (the 17,000 BTU JMOR mentioned) when it gets down to sub zero temps.
HOWEVER Just like when I ask the Eden Pure heater salesmen when they brag it will heat 1500 sq ft and I ask them to what temp.......Whats the outside temp,,,,,,,,Whats the insulation factor,,,,,,, Without knowing the shop size and insulation and outside temp and to what temp you want the shop,,, its hard to say what a 5000 watt unit will do
That being said and subject to your electrical cost, pure resistance electric heat isnt usually the cheapest thing out there (LP Gas or Natural Gas etc., especially high efficiency units)
BUTTTTTTT its simple quick cheap n easy to install with no flu or chimney or venting problems or plumbing etc etc and they do work well