how safe is it to run a kerosene heater in a shop for hours on end? the shop is vented ok i mean wind blows in that thing like driving your car with the window down at 90. also is it a good idea to get a c0 tester thing toknwo what the levels are in the shop. i just got a 215,00 btu heater and watn to make sure im as safe as can be shops about 30 by 50