Well, to be totally honest, it's the best little heater I have ever purchased. I made a makeshift type shelf off windowsill in kitchen to hold it, screwed it down. Open window partially. Make up a plate to accommodate exhaust and locked window to it. Made fireproof. Very important due to h8gh temperature of exhaust pipe.
But, this thing kicks a** ! I am very impressed with it ! Usage of fuel is minimal at setting #2. My preference. Kept my huge kitchen at 80° during construction with outdoor temperature at 26°. Yes kitchen insulation is already in. But will be using it in my double 40 foot steel container, that is NOT insulated yet, just to do work. I'm sure it has to be put on # 5 or max it out. I highly recommend this unit. For under $100 you can't go wrong...!!