Why don't they teach it that way?
As we finally step-function into Real Summer with some 90s, a local radio station interviewed an HVAC man for advice about AC. His advice was highly sensible: Open the house in the morning to pick up the free 55 degrees.... but don't wait too long to start the cooler. Start it a couple hours before you feel like it's needed.

I figured this out several years ago, after I switched to Old Peoples Time. When I was on Young Peoples Time, I wasn't awake during the Daily Free Delightful Coolness Special, so I just had to leave the AC on all the time.

Why start the AC early? It's a matter of thermodynamics. Maintaining the inside walls at 60 is much easier than bringing them down to 60 after they've picked up 70. Steady speed uses less fuel than acceleration.



Here's the point: I didn't figure this out from the theory of thermodynamics because I never learned the theory. The subject was 'covered' in high-school and college physics, but those courses never got around to the most important part. The courses started with the strange and quasi-scientific Three Laws, then slipped directly into some stuff about Carnot Cycles.

If they did teach the basics, I didn't catch on. I was thrown off by those Three Laws. Entropy is not a proper concept because there's no such thing as randomness. Closed systems are purely subjective human-designated concepts. After realizing that the Three Laws were nonsense, I didn't trust what came next... if there was anything that came next.

The basics are perfectly basic. Force, flow, friction, inertia. Same as Newton, same as Ohm. The units and equations are different, but the concepts are identical. I understood Ohm deeply in junior high, and picked up Newton easily in high school by analogy with Ohm. If thermodynamics had been taught this way, I would have understood it in high school.

Instead I had to wait until age 58, when I could build the concept from direct experience.

Just HOW basic is the idea? Well, both of my grandfathers, Missoura farm boys who quit school after 4th grade, worked with thermodynamics. One was a steam engineer at Detroit Edison, and the other was head of building maintenance for a school district.

I remember the latter grandpa (father's father) discussing how his old school buildings had been remodeled with drapt ceilins. Wellsir, afore the drap, them rooms had 12-foot ceilins, so the heat ended up wher hit wouldn't do ary good. But with the drapt ceilins, them outfits is easy het. (In standard English, "those arrangements are easily heated.")

Grandpa understood force, flow and friction. The drapt ceilin reduced the gradient between the radiator source and the attic sink, which meant less potential was needed to overcome the gradient.

Force, flow, friction. Them outfits is easy learnt.

Labels: Experiential education

  ¶ 8:32 AM