Myth: Heat Rises

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When it comes to getting the most effective insulation in place, not only for your dream home, but for your ice-fishing shanty out on the lake, your doghouse, your out-house, and that cat-house down by the swamp and the railroad track where you been spending most of your happy time anyway--it pays to take a few public-spirited things into consideration . . .
As any fool would seem to know, hot air rises--and Lawd knows there be plenty enough of it round these here cyber-parts to show the proof of that. But not every fool is aware of the fact that heat and hot air are two different things.
Heat is infra-red radiation, and as anyone familiar with the result of infra-red photography can see, heat is light; it occupies a position on the spectrum with all the other electro-magnetic wave-forms. In view of this fact, it would be understood by at least a few half-way perceptive fools that heat, as infra-red radiation does not require air, water, cast iron or anything else to be propagated through space.
I came to be thinking on these matters as the result of a major disappointment over some Styrofoam insulation I installed this year under the floor of the master bedroom. Though the rest of the house is heated by a cast iron wood stove, that bedroom is situated such that not much heat migrates back to that part of the house, so we've been heating that room with an electric space heater. The goal is to be able to use that more sparingly.
Now as any fool knows, even a fool hates to be made a fool of, especially by something like a 50 buck expenditure on foam insulation that doesn't seem to be making the difference. It still gets very cold down there near the floor--while most strangely, beneath that floor it stays fairly warm all the time. It's not a basement but a cement block walled "crawl space" running from a height at the entrance of about 5 feet where the house is built up over the slope of the ground--and that's where the master bedroom is.
Some fools will insist that since the earth radiates warmth, this accounts for all that warm air under the house in such an enclosed space. If this were the case, then the same would hold true for that garage size tool shed out there in the back yard--but it doesn't. It's just so cold inside the shed as it is outside--and its built over the same ground.
I kept saying to my sweet thing, "Sweet thing, it doesn't stand to common sense--it's almost as if the heat from the house is going *down* through the floor into that space under the house!" We spent a lot of money insulating that bedroom this year, including the bucks we put down for those R-19 fiber-glass batts that are now installed above the ceiling. Something plainly cock-eyed is going on here!
Enter the wood-stove . . .
Due to space considerations peculiar to our house, we had to install the wood-stove a lot closer to the wall than is generally considered safe. At closest proximity, a ridge of hot cast-iron is only 4 inches from the painted dry-wall. To avoid danger of fire, I at first installed a galvanized sheet metal shield behind the stove. On the wall, it extended so high as the stove-pipe which stands too close as well, about 7 inches.
I fired up the stove to see how this would work out. As any simple fool such as myself would suppose; for safety's sake, it would be good to provide plenty of buffer between the stove and the wall, so for the shield, I had covered both sides of a three foot square sheet of plywood to do the job. When the stove was good and hot, I put my hand on that sheet metal, to find that it was cool to the touch--but the air in front of it was highly heated. Fool that I am, I stood there going, "Hot Damn! What is this?"
Not even the hot air flowing over the reflective face of that galvanized sheet-steel was serving to warm it up. And what manner of fool would it take not to notice the difference between the warmth of the wall behind the stove pipe at its seven-inch distance, and the reflective shield at 4 inches? Something started to penetrate the dim shield of false knowledge that was installed in my head at school.
When it comes to infra-red radiation of heat, there is no up, down or sideways about it, it will radiate in any direction as heat, completely independent of any currents of hot and cold air, gravity or anything else. Some of the heat radiating from that wood-stove does of course serve to warm up the air, some goes into the furniture and into the dry-wall. And that still posed a fire-hazard back there behind the stove pipe.
I got an idea, quite an unconventional one, but figured what the hell, it's only for the duration of the winter months, and not really giving a hot fart what anybody might think of it anyway, I went ahead and tried another experiment: I took a roll of my wife's ordinary aluminum foil and stapled that to the wall behind the stove pipe. Again, it stayed cool to the touch. Well, hot doggies! I removed that bulky sheet-steel and plywood shield and stapled more aluminum to the wall as a replacement, so that now runs from floor to ceiling behind the stove--and it never takes on the least amount of heat.
That's what a fool like me has decided to call "insulation". And now, as I turn my mind back to the problem of that cold air in the region near the floor in the bedroom, I come to realize a few things, the main one being this: forget about what *hot air* does, as it always goes up in its motion. Forget about air! Infra-red radiation, heat as such, as waves or rays moves independent of the air, it goes down, it goes up, and it goes sideways, but the main direction it's going to move is toward any source of cold that would be drawing it.
Now don't ask a fool like me to explain just how or why a region of lesser heat or 'cold' would act as a sort of magnet for infra-red radiation. I am too foolish to have figured that out yet. I just know from empirical observation of the facts from the master bedroom that this is the case--from my cold bare feet, I am one fool who knows what he's talking about here.
Standard home insulation in the form of fiberglass rolls and batts is there primarily to interfere with, to block a movement of air--not radiation. It can't do a simple fool thing about the propagation of infra-red heat rays. That kind of insulation can trap air--but to what purpose? How much air can be found to move through a three- quarter inch thick sheet of tightly-packed gypsum wall-board?
Not enough to talk about. Heat radiation from the fire in a stove will radiate to the air and into the walls, and from the air into the walls. The heated dry-wall will radiate its heat into the fiber-glass batting. All the while, cold air on the outside of the house is drawing heat from the siding, the sheathing and the fiber-glass, and there is nothing to stop that fiberglass from radiating its store of infra-red energy, to heat the outside world.
So what earthly good, one well might wonder, is that fiberglass insulation at all? If its purpose is to stop a flow of air, there are certainly better, more solid materials suited to do that. If the idea is to trap air and not just block it, Styrofoam would be the better candidate because the structure is comprised of closed, impermeable cells.
So, I am one fool whose mind is totally made up when it soon comes to the job of building my own home on the land we are soon to buy. I will not use fiberglass. I will use just two materials: Styrofoam and aluminum foil.
If I can find the time for it this winter yet, I will go back down there beneath the bedroom and staple to the face of all that brand new blue Styrofoam, a single layer of Reynolds Wrap--and then we'll see just how much of a fool a fool can be, when it comes to the understanding that heat does not "rise", only hot air does that. Heat, like all light can be efficiently reflected, and therefore trapped to be preserved, kept from being drawn away toward any direction of lesser heat, for example down in the basement, or in the crawl-space beneath your average damned fool's home.
Heat is light, and like any other wave-length of light, it can be reflected with very little loss of energy into the reflecting medium. Like any other kind of light, heat goes right through glass. While glass can stop the flow of heated air, it will at the same time rob the air of its heat energy, due to the very low "specific heat" of glass as a medium (among the coldest in the room) and being transparent, infra-red radiation like any other sort of light, will pass right through the glass--without heating the glass itself, same as happens with foil reflection.
There is not much in a carpet or the boards of a floor to impede the light that propagates at the infra-red end of the spectrum. True, some of the heat energy will be dissipated into the carpet and flooring, bringing heat into those media to be trapped and ever so inefficiently stored. Wood and polyester fabric, despite whatever quantity of silicates, are not glass and will not pass the infra-red energy on without some appreciable loss: there will be molecules of elements in the wood and in the organic compounds of the carpet that will absorb and/or reflect heat energy, while the silicates (and whatever other compounds I am too foolish to know about) will, like glass, allow the heat radiation to pass through the carpet and the wood.
In short, infra-red radiation, as the form of light energy known as "heat", does not find an impermeable barrier in wood and carpet, and that is why it stays warm under my house in the winter. Heat can fall right through your floor just as easily as it can rise through your ceiling.
Have you ever heard of anything so foolish? -- Mackie http://vignettes-mackie.blogspot.com / "Who Did the Dahlia?"
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You can't explain this magnet effect because it doesn't exist.

Sure, on the news every day.
Want to get that bedroom warm? Use an electric fan.
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The whole point here is that such conventional wisdom as this, on the subject of heat in the teaching of physics is outdated and proven clueless--as demonstrated by the experiments described. So get out your little physics pennants, and wave them things all over the place till you're all full of tears and red in the face, if you think that will help.
You can sit there hammering on last year's physics texts like a bunch of Baptist Bible thumpers from Missouri, but all you are doing is stating the same old gibberish as if it were the holy gospel handed down from heaven.
You are able to memorize simple old facts and explanations, but you can't think the next thought. If all heat is not, at its foundation, infra-red radiation, if it is merely, as you recite (like some fanatic with his Koran) "a mechanical vibration of molecules," then you have NO WAY to explain the light-like reflection of heat from that reflecting surface behind my stove. But let every monkey have a say in his day of funny business . . .

And what will this one have to say, about the fact that the black iron fireplace screen that I store behind the stove until it comes time to put it in place in front, is always hot to the touch, while the foil stapled on the wall above and behind is always cool, no matter how hot the stove, pipe and screen? The characteristics of metal is not the point. Reflectivity is.
Get a clue!

The word you take is none but your own, as you entirely misconstrue the stated facts. The purpose of the silicon is dissipation of heat, precisely what I said about it, when I spoke of silicates being very poor insulators, indeed.
I am marooned on a planet of morons! I am besieged by blinking idiots, who even after the experiment is shoved in their faces, cannot, for the blindfolds of their dogma, even begin to see what it means.
So what is it really--plain ordinary blind dogmatism? Or is it the nasty old envy that every time arises when somebody else got to the idea first?
Mostly the latter, I'm sure. Because I know this tribe of monkeys called, "man".
The human species has evolved physically pretty well from the chimps (or whatever family tree) but so far as the competitive, aggressive nature of the beast, as is plain to be seen, he is still making the same arrogant grunting noises and hanging from the trees.
Have your fun monkeys. And when you run out of bananas, just look up, for all you know, there may be a higher branch! -- Mackie http://vignettes-mackie.blogspot.com /
"Who Did the Dahlia?"
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wrote:

LOL - Another NIA who doesn't.
Bob
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Seymour MacNicely wrote:

The surface reflects infrared. Heat is the result of the infrared energy being converted to heat energy when it is absorbed. Electromagnetic radiation is not the same thing as heat. Invisible electromagnetic radiation is not heat any more than visible electromagnetic radiation is. Thermal radiation is a process where heat energy is converted to electromagnetic radiation, sometimes some of which is visible light.
- Don Klipstein ( snipped-for-privacy@misty.com)
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-- Mackie http://vignettes-mackie.blogspot.com / "Who Did the Dahlia?" http://whosenose.blogspot.com
"Nothing can be more contemptible than to suppose Public Records to be True. Read them & judge, if you are not a Fool," -- William Blake, *Marginalia*
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Would you have any evidence for this article of faith?
Nick
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Dan Espen wrote:

It exists. It's called the second law of thermodynamics.
Dan Espen has a point, even if he doesn't express it very well.
http://www.radiantbarrier.com/physics_of_foil.htm
Paul
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Soemtimes I come home at night at open the door to my house and all the dark from outside leaks in. Same thing.
~M
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wrote:

Heat is the transfer of thermal energy, which can occur via conduction, convection, or infrared (IR) radiation, not just radiation as you imply. You are right that neither radiation nor conduction travel preferentially upwards--only convection travels "up" due to buoyancy. To solve heat loss, you have to look holistically at all 3 forms of heat loss, plus other practicality factors. Air is a terrible conductor & a super insulator, but it is transparent to IR and a great convector. Fiberglass and styrofoam and function as insulators by holding the air in place to keep it from convecting and block some IR in the mean time. In foam and fiberglass, air is the actual insulator, otherwise you'd use solid polystyrene or solid glass. Yes, fiberglass does block & reflect some IR, just like it blocks visible light--just 'cause it contains silicates doesn't mean it's automatically "transparent." Styrofoam works better than fiberglass because there is no air movement in its closed cells, but it's not used as primary house insulation because it is flammable and releases noxious gasses when burnt and does not roll up easily like fiberglass. Otherwise our houses would be insulated with only styrofoam. But go ahead, use it in your house. Not sure what you're getting at ultimately, but there's a lot more than IR radiation to consider in heat loss. Otherwise, you could just live under a tent of aluminum foil.
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I

Why don't you buy foil faced insulation?
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I'd say it's utterly opaque to IR. Glass itself is, for wavelengths longer than 3 microns.
Nick
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On Feb 6, 6:04 am, snipped-for-privacy@ece.villanova.edu wrote:

But, if the IR is making it to the insulation, the heat's already gone.
Off to buy some tin foil to put on the ceiling...
D
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1] The radiant heat from the stove is travelling a very short distance. Foil place across the room would do little
2] wood stove, cold room far away....hmmm could it be that the stove is sucking the air out of the room and replacing it with cold outside air??? Like every other woodstove on the planet.....
3] I am however beginning to lean in your direction on fiberglass. Foam seems so much more effective
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Even if foam is more effective, you'd have to seal every edge or you'd lose heat through convection.
Most foam I've seen seems to be about R5/inch. That's not that much greater than fiberglass. Installation would be way more time consuming.
Bob
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No...
It won't help as much on the ceiling, R2.01, vs R0.84, with no foil, for upward heatflow.
Nick
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snipped-for-privacy@ece.villanova.edu wrote:

image. Go figure.
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With a black body peak temp of 2898/3 = 966 K or 1280 F...

Googling IR film spectral sensitivity, I only see plots from 0.2-0.9 microns.
Nick
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Apparently Nick was referring to the wavelengths of IR radiated by objects at or a little above room temperature. That is indeed pretty much all longer than 3 microns, and it won't go through glass. IR film won't respond to it either.
IR film mainly responds to wavelengths less than .9 micron. IR CCD cameras respond a little farther out, to maybe 1.1 microns maybe a little more, but not the room temperature thermal IR range. You need those thermal imaging jobbies to see those long wavelengths.
- Don Klipstein ( snipped-for-privacy@misty.com)
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I only read the first few paragraphs; I can't imagine anyone reading it through. But the question is, why would you write such sillyness? Heat is infra-red radiation! I guess we can save a fortune on insulation, forced air furnaces, and numerous other items with that insight.

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