OK, so I have been kicking an idea around in my head ever since I saw this picture here on the forum
mikeschn wrote:You've seen this one, right?
So I was thinking about how to do a similar thing with propane. I have drawn up some potential plans but I am not so good at getting pictures of my own onto the internet, so I will try to describe what I am thinking in as much detail as possible:
Built into a teardrop wall, appropriately insulated from the wall with fiberglass or something so that there cannot be damage to the wall, is a metal box. This box is divided into two chambers down the middle of the wall so that the side of the box that is fully inside the trailer is COMPLETELY separated from the side that is in contact with the outside. Basically it would be something like two chambers, each approximately 2x10x10 butted up against each other.
In the outside chamber are vents to the outdoors in the top and bottom allowing fresh air to enter and exhaust gasses to vent. As a source of heat, I envision a cannibalized propane lantern or perhaps two of them located near the bottom of the chamber but in such a way that the valves that control the amount of propane would be able to be accessed from inside the trailer. The reason I thought of a lantern mantle as a source of heat was that it would be cheap and you could probably use it mostly intact. Above the lantern mantles would be a copper heat sink, perhaps stolen from a computer, located in such a way as to catch as much of the rising heat as possible. This heat sink would be mounted to the inside dividing wall perhaps with the copper passing through the wall but not in such a way that exhaust gasses could also pass through the wall. A similar heat sink would be mounted inside the inner chamber. Perhaps one like this one:
In the heat sink pictured the fan would force unheated inside trailer air through the sink, picking up heat and then pushing the warmed air back into the trailer. If you wanted, it seems like it would be simple to use a sink without an attached fan or perhaps add your own. For that matter convection alone might be enough to heat the inside of the trailer. Convection might be better for those who have limited or no battery, while the fans might be better with a 12v source of power.
I would also add a BBQ lighter as a source of ignition, and I think I would have a tiny glass observation window so that I could see if the lantern was lit.
If the lantern valves were sufficiently sensitive, you could have quite a lot of control over how hot the heater would get. And you could have two independent mantles so one or both could be lit at the same time, further controlling the temp. another option would be to add a rheostat to the fans for variable speed airflow over the heat sink.
Ok now I want to hear all the opinions on this project that I can get. My own thoughts are that I think that it would be safe. I think the lantern mantles would give off enough heat to warm the trailer, perhaps too much, but we would be losing quite a bit of heat with the exhaust gasses, so maybe it would be just right? I have no feel at all for what it would cost to fabricate. Since I can't seem to find a vented heater in a size small enough for a teardrop st nearly any price, certainly not one I can or want to pay, maybe price is a moot point. I could be wrong but I don't think it would cost more that $50, and potentially much less...especially if you had stuff laying around you could use. I don't think it would use up too much propane, especially if you could plumb it to a large refillable tank. I suppose how much propane used would depend on the type of lantern, how efficient you could make it -by which I mean how low you could set the lantern and still have adequate heat-, and what temperature was desired and how much that desired temperature differed from the ambient temps.
So... what do you think?