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+--- Thread: best way to warm a minivan ? (/showthread.php?tid=86311)
Re: best way to warm a minivan ? - andypie48 - 10-21-2009
thank you all. some really good ideas.
the space blankets are cheap. and there is a poncho too.
thermarest is good, but expensive, although there are a lot of variations and it will be hard to choose.
Re: best way to warm a minivan ? - davester - 10-22-2009
macphanatic wrote:
I use what was called a space blanket (about 30 years ago). It's red on one side and silver on the other. I put the red side down with a foam pad and sleeping bag on top. The silver side reflects the heat up and helps prevent heat transfer to the ground. The blanket (more like a tarp) was also sold for survival purposes. Wrap yourself in it, red side out. Absorbs heat from the outside and helps keep you warm on the inside. Works quite well.
You could hang thick blankets along the walls of the van. It won't warm it up, but it should help keep the cold from radiating in.
Sorry, but that 's not right. Heat flows via radiation, conduction and convection/advection, all very different mechanisms that most people have little understanding of. In some situations only one mechanism is significant, in other situations all three contribute to heat flow.
Space blankets only work to reduce radiation and radiation only operates through transparent materials (i.e. air). All space blankets require an air gap between the heated object and the silver reflector which is why they work only when very loosely wrapped around you. Wherever your body (or anything solid) touches the silver surface you completely negate its effectiveness. A space blanket under a foam pad does nothing, and will not prevent heat transfer to the ground. In fact, since it is aluminized, it will probably increase heat transfer to the ground because of the very high thermal conductivity of aluminum.
A thick blanket on the wall of the van will not stop cold from radiating in, since cold is simply a lack of heat and therefore does not radiate. If hermetically sealed to the side of the van a thick blanket may stop a small amount of heat from conducting out through the van walls (and would do nothing if just hanging loosely on the wall) but it would have an absolutely minimal (I would go so far as to say undetectable) effect considering what a small percentage of the total van surface area that would cover. It would be much smarter to put those blankets around your body, which has a much smaller surface area.