Mine holds about 10 gal of either kerosene or diesel. I always bought red diesel and the fumes were not an issue but it also didn't run more than 20 min in my 1800' shop with 14' walls when it was 25* outside.I have used those ones that sit atop a Propane Tank. They put out good quick heat!
It has a digital thermostat with 5* increments. I'd set it to 45 over night to keep my plumbing from freezing, then come out to work and set it to 65*.