I have read a lot of folks using petro heaters in their shops along with the comments relating to black soot, headaches and co. etc. I have two buildings that I heat for my woodworking business. The garage which I use as the mill is heated with a combination wood/coal stove by Russo. In the warmer winter days, a good wood fire will heat up the mill for several hours using wood scraps. On colder days I feed the monster with coal. It's reasonably cheap and produces a consistent temp throughout the day and night. I throw a few coals in every 3 hours during the work day and feed it generously at night around 11. This lasts all night until around 8 when I open shop. I give it a little shaking and begin the routine once again. Nothing like the feeling of that nice hot stove coming in from the 0 degree morning to begin work. It is a very dry heat so I often put a pan of water on the top to give off some moisture. Keeps the coffee hot as well. The shed which is my benchwork shop is new and well insulated. I heat it with new hydronic electric baseboard heaters which I purchased at WW Grainger. They heat the shop very well and economically too. My electric bill is not out of sight either. The big problem here is summer with the humidity. Living 50 yards away from the ocean can raise havic on metal so it keeps me busy cleaning all the machines daily and making sure that the rust stays away. I have no problem here but it is certainly more work than winter when the air is dry.
I wrote this little arcicle for those of you that have room and may want to heat with wood and or coal. I like it although the coal I got this year procuces more ash than coal of other years. My supplier is trying to get the better grade of coal but is finding it difficult this year. He delivered another 1/4 ton yesterday and says this batch is better. I think that wood and coal are better than liquid petro or liquid gas. They produce odors and moisture. Don't try to heat a cold shop with them for instant heat. The machinery will sweat and will rust. Keeping a shop warm all the time is best at least at 45 degrees Far. and will not produce as much moisture as will a stone cold shop at 10 degrees and turning on the heat. A coal stove will last all night long at even temperatures unlike wood.
Hope that I helped.
Gusty