Why Isn’t my AC Working!?

It’s spring, mother nature is keeping you in the eighties or nighties already. Your office is unbearable. The intern has somehow duct taped ice bags to his back and ruined his office chair in the pursuit of not melting. It’s time to turn on the AC and nothing happens. Kronk throws the lever and the air blasting in is hotter than the pavement Dave the Intern cooked his lunch on. What happened?   The Little Problems There can be a million things wrong with your AC. Some issues are catastrophic and very expensive to repair as our lead sales guy Scott learned the hard way just a few weeks ago. Other issues are smaller, cheaper, and merely annoying. Did you Turn on the Power? Most central cooling systems have a dedicated circuit breaker to turn them on and shut them off for maintenance and long-term deactivation such as through the winter. Turning off this breaker in the fall ensures your air conditioner physically cannot be engaged in the winter and accidentally damage itself. Depending on your situation, you may not have known this switch exists or your building maintenance team just hasn’t turned it on yet. If you enable your air conditioner in your thermostat, crank down the temperature, and nothing happens, this is the first thing to check. If you know where the breaker for your AC is, check on it. If you don’t, contact your building maintenance team […]

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We still use Ice in AC TODAY!?

In the early days, perhaps up to the 1950s or so, Ice was your standard cooling solution. If you didn’t have a refrigerator, you had an ice box. This solution wasn’t as on-demand as modern AC, but it had a nice benefit: no high electricity bills. Every summer as we turn to AC to avoid sweating to death, we’re faced with our soaring cooling bills. With this in mind, some manufacturers actually still use ice in HVAC systems today.   Why ICE? Prior to the invention of air conditioning, ice was pretty much the only cooling thing available. Today, we have a million and one ways to cool things, but they don’t entirely hold up to ice. Water by itself is amazing at storing and conducting energy. Just think of the last major snow storm and how long it took for that to melt off afterwards. North of Philly here, our last major storm dropped eight inches or so that actually stuck to the ground and it took days of 50+ degree weather for it to melt. This makes Ice an excellent way to store “coolness”. On top of that, water is non-toxic, abundant, easy to store, and easy to cool. The other famous alternative might be liquid helium or liquid nitrogen, both of which are used in industrial cooling applications such as MRI machines and particle accelerators. The problem is that they’re not easy to cool, can involve vast […]

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Why Are Compressors Measured in Tons?

When we look at compressors, there are a lot of numbers going around, but one of the bigger ones is the Tons. We sell compressors in all manner of weight-ratings, from less than a ton to hundreds of tons. The thing is though, this doesn’t mean we need a crane and a massive truck to load the compressor before it ships out. Compressor tonage is not actually a measure of weight. In fact, it is the result of some weird and convoluted math and history.   Old Fashioned AC Before we had the modern air conditioner, there were just a handful of ways to actually cool a room or a building. You could open a window, sit in front of a fan, use an evaporative cooler, or get a block of ice. That’s right, once upon a time we didn’t just have “ice boxes”, we had ice-conditioning too. The precursor to modern refrigeration was massive chunks of ice, usually cut from frozen lakes in the north and hastily delivered anywhere cooling was needed. You would go down to your local ice house and buy however much your fridge or cooling system needed. For building-scale cooling, there would be a block of ice essentially placed in a special cabinet in the air ducts and fans would blow air over it. The ice would remove heat from the air and melt. The air would be cooled and circulated around the room or […]

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What About the Other Compressors?

Just how many ways are there to squeeze down a gas? If you look at the entirety of the industrial world, there’s probably a few hundred different devices. If you look at HVAC, luckily the list is a lot shorter. The air conditioning world relies primarily on five compressor designs.   Reciprocating This compressor works pretty much exactly the same as a car engine does, but without the gasoline and combustion. Inside a car you have your cylinders and pistons. When the piston moves up it compresses, when it goes down it sucks. The same principal is used in a reciprocating compressor. At the base of the compressor there will generally be an electric motor, which turns a shaft. The shaft has a bend in it to allow for offset motion. At the bend there’s a connecting rod, which links the shaft to the piston. When the shaft spins, the piston moves up and down. On the downstroke, fresh refrigerant is pulled in. On the up stroke the refrigerant is compressed and injected into the refrigerant loop. This particular design is popular in residential scale compressors. There are more parts involved, so there’s a greater chance of hardware failure, but the well understood nature of the piston and cylinder as well as massive manufacturing tolerances make them cheap to manufacture. Consider, steam engines were around in the 1800s, and this is the same principle as their driving pistons. The complexity […]

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How Does a Scroll Compressor Work?

Once upon a time, I thought there was really just one kind of compressor. How many ways can their possibly be to make something smaller? Turns out, quite a few. Each type of compressor has its own quirks. Some designs are more efficient. Some require less maintenance. There’s just this endless list of trade offs in designs to get a […]

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When CAN we turn on the AC?

As the weather warms up, we’re caught in a bit of a pickle. Some days it’s 60 or 70 degrees outside, but other nights we can still see lows dipping to 26. Some days we look to our AC systems and desperately want to run them, but is it time? Is it good to run AC for just a few hours a day? Is it good to run them in the bitter colds nights? Are we going to regret running these?   Physics Hate Us We’re going to run into a few issues running our air conditioning in less than roasting weather. We’ve built modern AC, from window units up to multi-ton rooftop monsters, to take a brutal 100 degree summer down to a cool 70 degree oasis. These machines can create temperature drops from twenty to forty or more degrees. This involves creating some intense coolness inside the air conditioner. If the ambient air is 60 degrees and we drop that by 40 degrees inside the air conditioner, we’re going to make it 20 degrees inside. This extreme cold will create ice, the great nemesis of all things mechanical. We don’t start to get to ideal temperatures until it’s about 70 degrees outside. Around that point, we can actually run the AC without having to worry so much about the ice build up. Why is ice a problem? It’s mother nature’s wedge. As water freezes it expands. As water […]

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Why Can’t We Crank the Heat AND the AC?

We’re entering the awful, awful season where mother nature will swing between very warm and very cold. Just last week we had a good four inches of snow, a high of forty degrees, and a low below freezing, only for a high of over fifty the very next day. This weather calls for both heating and cooling in some circumstances, but we can’t always give you both.   Fond, Freezing Memories The schools I went to growing up had a very annoying problem: they could heat or they could cool, but they could not do both. This was always problematic and stupid to kid-me sitting at his desk contemplating a textbook bonfire for warmth. Of course, it’s wasteful to run the heating and cooling at the same time, but surely we can just turn off the furnace and crank up the AC? We’ve done it in the car all the time, you just twist a knob and you go from freezing to roasting and vice versa. At small scales, climate control is pretty easy to accomodate. You use air ducts and mix hot and cold air to get the net desired temperature. Facilities with forced air heating and cooling can pretty readily fling themselves from one temperature to another like your car. Other facilities have completely separate systems for heating and cooling. There might be a little split AC unit in every room and a master hot water heating system. […]

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What is Short Cycling?

Everything around you is designed with a specific set of uses. Consumer lighting is generally designed to be in a warmer environment, be turned on for a few hours, then be shut off for a few hours. Your car is designed to start up, run for at most a few hours, reach a few thousand rpm, carry a given load, and then shutdown for a while. Everything is designed with these use constraints, that they’ll be on for a given time, achieve a given performance, and then shut down. We call this off, on, off pattern a Duty Cycle.   Getting Out of Cycle Your car works wonderfully when you use it as its designed, doesn’t it? Short trips to the store, the commute to work, and the occasional long haul trip all work out just fine. What would happen if you didn’t use it as intended? Imagine if you ran it for short periods. Start up, drive to the stop sign, shut off. Start up, drive 5 minutes, shut off. Start up, drive around the corner, shut off. Something is going to break eventually. Either the starter will have overheated or the battery will die, but it’s going to work a lot shorter than desired because it’s designed Duty Cycle is being interrupted. This disruption, a constant start-stop is short cycling. The system keeps going through cycles, but they’re shorter than they should be. Just as with the car, […]

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Unfreezing a Freezer

How do you run your refrigeration hardware through the winter? How far does our industry go to keep a fridge running in the winter or a hospital chilled in a blizzard? There are a number of technologies at play, all working to manipulate the hardware to do their bidding. These are collectively called Defrost Controls.   Let Nature Take Its Course The simplest defrost system is little more than a few switches and a timer. In many systems, the greatest concern is that the evaporator coil may freeze over. This is especially common with industrial freezers. This is a year-round problem and it can be caused by staff frequently entering and leaving a freezer. The freezer temperature increases and many refrigeration systems end up running for entirely too long. The evaporator coil builds up ice from being chilled too much. In configurations like this, the simple solution is a time delay. The compressor shuts down, but the evaporator fan is run for an extended period, forcing relatively warm air over the coil. Whatever ice was there melts and the system can return to it’s regular cycling after the defrost cycle finishes. This can be set to run on timers or in more advanced systems, as necessary using temperature readings. In some installations, it can even be boiled down to a timer which triggers the cycle once every 24 hours and just turns off the refrigeration system for an hour to […]

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Freezing a Freezer

It’s the very end of fall, bordering on winter, and we’re going to look at air conditioners and refrigeration. Every year, someone learns the hard way that you both can and cannot run an air conditioner in the middle of winter. Let’s get to it before someone else learns a hard, expensive lesson.   Who Runs the AC in WINTER? Someone out there will ask, so let’s head it off sooner than later. In an ideal world, you could pull in fresh, outside air, particularly when it’s cooler outside to cool your facility. This works in homes and even small businesses, but there’s challenges when you move into specialist industries and larger scale operations. Hospitals can’t just open the windows, as it can expose the patients to bacteria, viruses, and allergens. Restaraunts can’t leave their frozen food up to mother nature’s whims to keep it cold and safe. Large data centers need to be sterile and cool year-round, to the point that the air outside cannot easily keep up against the heat generated inside. Manufacturers in numerous industries need cool areas, for chemical work, storage, freezing food, and so on. In all of these cases, nature is too unpredictable, too unreliable, or just too complicated to fulfill our needs. These places need to run air conditioning and refrigeration even through the coldest and darkest of winters.   The Freezing Problem Regardless of application, all refrigeration systems have one big nemesis […]

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