The advantages of a non electric pellet stove are that there is nothing much to go wrong. Unlike a conventional pellet stove, there are no blowers, no auger and no control board. This means no blower noise and no consumption of electricity. It also means that there can be no heat exchanger - heat transfer must be by radiation from the body of the stove, so a non electric pellet stove will have either a long path to the flue, or a body of sufficient weight to conserve and radiate heat. Electricity free pellet stoves must be gravity fed. The pellets slide down to the fire box when the fuel in the fire box has burned enough to allow space for fresh fuel. It's the design of the airflow through the firebox, directed away from the hopper feed, that prevents the pellets in the hopper from igniting. There can be no thermostat. Heat regulation is always by controlling the maximum pellet feed, regulating the air to the burn pot, or both. Auto ignition isn't possible either, these stoves must be lit manually Possible improvements would be to use a thermocouple and valve to regulate the flow of pellets, so that pellets could be dropped remotely to the burn pot. A thermopile, ( a series of thermocouples joined together to produce more power ), might be sufficient to run a auger. I'm not aware of any non electric pellet stove using this idea. Useful if you live off grid, a gravity feed pellet stove is usually used for camping or a cabin where the building or tent housing the stove has good ventilation. None except the Wiseway has a UL certificate, so insurance for a dwelling using them will be hard to get. If you know of a non electric pellet stove with a UL certificate, let me know using the contact button at the bottom of the page and I'll be pleased to include it. Here's a link to an explanation of UL 1482