Measuring the Heat

Have you ever wondered how your heating system knows to turn on? Or to turn off? You could say “the furnace controller tells it to” and “the thermostat tells it to,” but that’s not the whole picture, is it? We need a way to measure the temperature inside the furnace and inside our homes. It has to be durable, reliable, and affordable. It doesn’t have to be precise, but it must be right every time it’s measured.   A Complex Web of Technology There are a staggering number of ways to control a furnace through temperature input. A brief and nowhere near all-inclusive list of techniques include: Gas Expansion Tubes, Bi-Metal Switches, Bi-Metal Coils, Thermocouples Driven by a Pilot-Light, Thermistors, and of course modern IR Temperature Sensors found in your enthusiast-chef’s kitchen. These devices are all in some way sensitive to the heat. Bi-Metal systems expand as temperatures change. Measuring the expansion reads the approximate temperature. Gas Expansion Tubes have an internal change in pressure as temperature changes. The pressure can be used to calculate temperature. Thermocouples generate an electrical current when they’re heated. Measuring the current allows you to determine the temperature. Inside a furnace, they’re often heated directly by the pilot light or burner to read flame temperatures. Infrared Thermometers measure “Blackbody (Wikipedia Link)” radiation, but aren’t all that effective around metals or the air. And lastly, we have the humble Thermistor, which varies it’s resistance based on […]

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Albert Einstein Designed a Fridge

We all know Einstein as the man who invented E=MC2. He also used experiments to find Avogadro’s Number, proposed that light was not just a wave but also a particle (a photon), created the General Theory of Relativity, and among all his accomplishments, designed a fridge without a single moving part. As with all things in our industry, this relied on cheating the laws of physics into doing our bidding.   Motivation The first refrigerators were deadly machines. They used a similar compression system to what we have today, but there was a catch. The new technology had a short lifetime before failure and when it did fail, it failed deadly. At the time, there were three major refrigerants: methyl chloride, ammonia, and sulfur dioxide. Methyl Chloride can disrupt the central nervous system, starting with drunken symptoms and ending at paralysis, coma, and death. Ammonia is incredibly corrosive and will cause irritation of the skin, eyes, and lungs before more severe symptoms such as blindness and death by lung failure set in. Sulfur Dioxide is similar to ammonia, it attacks the skin and mucous membranes, and with the right circumstances can damage and destroy the lungs, and even interfere in the heart. The seals on early fridges would fail at random due to the newness of the technology, variations in product quality, and perhaps even outright design flaws. When such a failure occurred, toxic gasses got into the air, and […]

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A Rubberband Cooling System

Have you ever come across something so weird, that you had to try it on the spot, then stalled the entire company with “Hey Bob! You gotta try this!?” Then, that phrase spreads like a plague, until everyone’s doing nothing but that weird thing. Well. We did. While researching some topics to share with you, dear readers, I discovered that Rubber Bands are a refrigerant. Kind of. When you stretch one, it heats up, then cools down. When you let it return to it’s original length, it gets cold. The temperature variance is perhaps 10-20 degrees from max cool to max heat. It’s something significant. Significant enough to even build a fridge of sorts. That’s right. The next time your stranded in the late 1800s, you can make a rubber-powered air conditioner for your little cabin on the prairie. For the proof, check out this youtube video we’ve just watched three or four times. At first we were looking for the hidden ice or a fan, but… after extensive testing of rubber bands, we’re sure it’s real.   Weird, right? The Wrap Up So, as always, what do you want us to cover? Let us know in the comments below.

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