Even draughty tin sheds are being heated succesfully by Kroll heaters. Kroll heaters are mostly used in the automotive sales, repair and associated industries, plus the work depots of federal, state and local governments, simply because these people have an abundant supply of waste oil on hand. Alternatively, you can have it delivered by a waste oil merchant very cheaply. Call for a guide to prices and merchants in your area.
All Kroll heaters run on waste oils, but there are two distinctly different types of Kroll heater.
The smallest model, the Kroll 'Kozy' is a vapourising heater, that is, the oil is regulated onto a hot cast iron pan inside the furnace where it vapourises into a gas, and it's the gas that burns.
All the larger 'SZ' models are atomising heaters. Their unique burner mechanism preconditions the waste oil and sprays it into the stainless steel combustion chamber where it is ignited by electrodes.