Why is the AC Hissing?

Air conditioners produce liquid water by design and by the simple nature of physics. Sometimes this harmlessly leaks out around the air conditioner, such as with window units, and sometimes it leaks when a drain gets blocked. There is however, a second leak an air conditioner can develop: refrigerant leaks.   The Cooling Compound Air conditioners work by exploiting physics around state-changes. When liquid turns into a gas, it can absorb heat.The effectiveness of the state change varies from compound to compound. For air conditioning, we tend to use things like R134a (freon), R12 (phased out/illegal in much of the world now), and even propane. These are all chemicals which have particular properties ideal for cooling. For example, they won’t turn solid at 0 degrees C like water, so they won’t clog up the air conditioner’s tubing and fittings. These chemicals though have some downsides we can’t really escape. Propane is outright flammable and probably capable of turning your air conditioner into a flaming set piece in the next post-apocalypse movie. R12 destroys the ozone. And R134a is toxic. It causes a wide range of symptoms from headaches to hallucinations and death in the worst case exposures.   The Hissing Leak When the air conditioner is running or has recently been run, the refrigerant will be highly pressurized. In order for us to make it work, we compress it. We’re cramming a lot of material into a small space, which […]

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Carbon Monoxide Detectors

Last week we covered how a draft inducer and it’s attached pressure sensor can help prevent Carbon Monoxide from leaking out of a furnace. This week we’re moving up to the next line of defense: a dedicated Carbon Monoxide Detector. These are often installed in new homes and offices as required by local building codes in most of the United States. Where they’re not installed by construction, they’re usually installed by the facility’s owner as a precaution.   What’s the Big Deal? Carbon Monoxide is one of the deadliest, common compounds in the world. It’s is a colorless, odorless gas that will kill you at the right concentrations. There’s only two ways for someone to know they’ve been exposed to a harmful dose: Use a detector or Recognise the Symptoms before it’s too late. The initial symptoms include headache, dizziness, weakness, vomitting, chest pain, and confusion. In large part, these common symptoms can be attributed to hundreds of other ailments, including the common flu. Greater exposure can lead to passing out, arrhythmia, seizures, and death. Even then, there will be longterm complications, including memory problems, movement disabilities, and fatigue. Most people are not able to detect and react to these symptoms as Carbon Monoxide poisoning before it’s too late. They’re often waived off as a flue or some other lesser problem until it’s too late.   How Do We Detect An Invisible, Colorless, Odorless Gas? While Carbon Monoxide itself is […]

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Preventing CO2 Poisoning with Pressure

We have rollout switches and temperature sensors to prevent fires from spreading beyond the furnace. What about exhaust gasses? Almost every heating fuel we use produces deadly gasses. CO2, NO2, and more. If these gasses escape your furnace, you’re either going to leave the building or be killed by the gasses. It’s essential that we keep these gasses away from you. Your furnace has some very interesting ways of doing this and detecting a deadly hardware failure.   The Draft Inducer Older furnaces rely on physics and chemistry to get the CO2 out. As your furnace runs, it creates hot gasses. The hotter a gas is, the higher it rises in the atmosphere. As long as the exhaust is hot, it should rise up into your chimney or exhaust flue and be vented safely outside away from people. This isn’t entirely ideal, the exhaust is limited by the temperature difference, slowing it down. It’s possible for wind and other atmospheric conditions to disrupt the exhaust flow. There’s no mechanism to detect and respond to a blocked exhaust path. Modern furnaces don’t let the hot gasses just meander out the chimney. We use Draft Inducers, essentially blowers built just for furnace exhaust. These little blowers kick on a minute before ignition to vent the combustion chamber and usually remains on until after the furnace has shutdown. On the surface, this just makes the furnace burn cleaner. If there’s less carbon dioxide […]

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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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