Would like to hear more about this ventless approach.
I originally got an 18,000 BTU "bluflame" heater (with thermostat) from Harbor Freight to help make a mobile home livable in the winter; It did very well in that application (note: these are not apparently legal in California).
Many farm and ranch stores seem to have them during the winter, and the are availiable on line. They are also available in IR versions, and with a fan option, in several BTU levels.
Several other folks that I know of have also had good luck using them in well ventilated sheds, garages, popups, travel trailers, mobile homes and as an emergency furnace backup. they come in versions ranging from around 6,000 through 30,000 BTUs (likely greater) in propane natural gas or both (the dual fuel units are more expensive). One person I know bought the non-thermostat version and it, like the buddy heaters, uses more propane because it does not reduce and shut the heat down temporarily at a set temperature (note: the temperature knobs are not calibrated other than 1, 2, 3, etc.)
My good results ended when I decided to try it while camping (between 9,000 and 11,000 feet);
the most immediate problem (in a 12x12 Alaknak (Cabela's) tent was the ventilation on that version of tent was not adequate to deal with the water vapor produced by the unvented heater (all combustion seems to produce some amount of water vapor, which goes up the chimney with vented heaters) resulting in condensation on the inside of the tent and waking to a cold shower. Note: since then The ventilation has been increased ion this tent so this may not be an issue on newer versions.
I have also tried other versions of blueflame heaters, propane barrel heaters, and IR propane heaters (and almost every other type of semiportable heater); the vented ones were likely safer and the thermostat controlled ones the best overall results.
The biggest down side of the thermostatic controlled blueflame heaters was that some have the temperature sensor at near the top of the unit; which just happens to be near shoulder height while laying on a cot and higher than me when I'm laying on an air mattress. This results in a very warm upper portion of the tent while I sleep near or below freezing in the cold lower part of the tent.
One potential show stopper with all "low oxygen sensor" devices is that some run poorly at high altitude, shutting down when needed or not starting.
I did inadvertently fall asleep with one running once; only to wakeup with shortness of breath and a heater that had shut down (it worked thank goodness) due to low oxygen (and thus my recommendation against sleeping with such a device running).
Blufame heaters typically have a relatively large metal enclosure and this is one of the reasons that I stropped trying to use them tent camping. The buddy heaters (which so far are not offered with a thermostats), are by far more portable and a better choice, IMO, for small mobile heating. However, the advantage of the thermostat is large enough that I am greatly tempted to modify a buddy heater with the guts & thermostat of a blue flame heater to give a short, easily portable thermostatically controlled quality ceramic heater that has lower/better fuel use.
Note; on the ZODI you might try substituting a 12 volt computer fan (they are available in many sizes, cfm ratings and noise levels) to make your unit more compatible with your needs.
Enjoy!
