Folks, I've got a question that's been eating me since I first heard about heating dilemmas concerning some camping situations. I assume most campers have a fire going. What about a steel pipe in a U-shape under the fire, with flexible tubing going to the camper like dryer tubing? That way the surrounding coals heat the pipe, and a PC fan could push the heat into the camper. You could attach a thermostat to the fan so that it would shut off whenever the temperature desired was reached, and even after the fire has died down, the heat from the coals is still hot enough to give you warmth through the majority of the night.
Great idea in theory.
In reality, there is an ever present danger that because of a crack/hole/etc, CO and other fumes would also be pulled into the camper.
Manifold heaters used to be a popular option in cars before heaters were standard equipment.
A pipe or tube was fitted over the exhaust manifold, and run into the car.
As the car traveled forward, and from the fan blade turning, cool air was drawn through the pipe, over the manifold, and exited into the car as warm air.
Worked very well, until the manifold cracked or began to leak.
Rob
Waiting for "someday" will leave you on your deathbed wondering why you didn't just rearrange your priorities and enjoy the time you had, instead of waiting for a "better" time to come along...