Here are links for some propane space heaters that are similar in design to the day-night heaters used in 1950s and 1960s trailers. They do not require electricity, instead using a thermopile generator, and can be controlled with a thermostat. They vent outside, one through the wall, one through the roof:
Direct vent wall heater (vents through the wall) - surface mount, 7500, 18,000, and 29,000 btu models, 18x22x6 surface mount (7500 btu unit)
Top vent (through the roof) - partially recessed, 66" high, 14" wide, 25,000 BTU and up
Linear Mode
