In article , (David Combs) wrote:
Keeping warm via hot air: works by conduction, but
not conduction like sitting bareassed on a warm
block of steel (much heat transferred to you
per second),

but via super UN-dense air, with minuscule ability
to store heat (per cubic foot) than eg steel.

I recall from a thermodynaics course eons ago
that whatever the materials, the amount of heat
energy flowing from one to the other, per second,
is 100% *proportional* to the temperature *difference*
between the two.

With respect to conduction, yes...

So, while an 80-degree (F) block of steel would
be able to transfer enough heat to you (r butt) to
keep you toasty comfortable even with an open window
with 30 or 40 degrees outside, perhaps, no can do
via hot air. Temp diff must be much greater than
the 99.6 - 80 = 20-degree difference via the block of
steel.

Tell you what: you drop trou, then sit on an 80 deg F block of steel, and tell
us if it feels warm. Stay there a while.

This may come as a surprise to you, but if a 98.6-degree human sits on an
80-degree block of steel, the direction of heat transfer is *from* the human,
*to* the steel. Not the other way around. After thirty minutes bareassed on
that block of steel, you're going to be shivering.

So you gotta blow hot air at you for the same warming,
but so hit that it's stifling (sp?), making you feel
really crappy, even nauseaous.

Nonsense. Forced air heat isn't "stifling" hot.

Then, there's heating via radiation, like by a cast-iron
radiator, an electric (fanless) radiator, the sun, etc.

Those pictures of resort-like ski-areas, all these people
lying around a swimming pool, in their bathing suits,
when it's maybe 30-degrees -- they're kept warm by
radiation from the sun (and by having the wind blocked).

Uh-huh. Right. I guess you mean 30 deg *C* here.

And it's a *much* nicer experience than being kept warm
only by a blast of hot air (sun blocked from warming you).

Different strokes...

Nice thing about cast-iron radiators is that you can
open the window, allowing nice (cold) fresh air to
circulate through the room somewhat, and yet you're
still warm (via the radiation).

You have an *odd* definition of "warm".

(I grew up in Texas (san antonio), and our house had
forced hot-air, and it would almost make me vomit.

Well, that's the source of your trouble - you shoulda used an air conditioner.


--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?