Variable Speed Compressors

Multi-speed compressors are a step in the right direction, but what about outright variable speed ones? Think about it, a two or three speed compressor has to pick the best speed for a given environment and it can only run at those two speeds. When it’s incredibly hot, full speed ahead. When it’s cooler, low speed. In between however, it becomes a game of the lesser evils.   Fixed-Speed Flaws This fixed-speed issue can be a bigger problem in the right scenarios. There’s only really a handful of conditions where the compressor can hit peak efficiency. You can crawl around the parking lot or go at highway blazing speeds, but you have no support for those middle roads between town. The same is true of the two speed compressor. The system can be forced to oscillate between stages or even be trapped in a single stage if the conditions are right. When it’s hot out, you’ll never get to use that second, lower speed. When it’s in between, the low speed might not be able to keep up and it’ll have to cycle between speeds, never really saving anything or improving comfort. It’ll almost always be this battle of the lesser evils: power hungry high speed and be too cool or have to work on wider margins of error, or fighting a losing battle with the low speed constantly running and only delaying the inevitable need for the high speed […]

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Multi-Stage Compressors

We often think of compressors as single-state devices. They’re on and they’re off. This holds true for most window units, portable indoor units, and even a number of central cooling systems. This simplifies things and lets us save power. Compressor on, hit target temperature, shut down. It’s better than running the compressor 24/7 and achieves the desired result.   Full Throttle The problem with this is that we have to constantly cycle. Imagine if your car had 1 speed. Instead of a gas pedal, you just had a button. Push the button, your engine revs itself through the roof, you do a burn out from your driveway, let off the button to avoid the kid running into the street, and you come to a dead stop in seconds. That’s how a single-stage compressor works and it’s a little wasteful. With this back and forth, on and off approach, you can never actually hit a precise temperature. You just hit a temperature range. When the thermostat is set to say 70 degrees, the air conditioner kicks on and runs until the room is approximately 65 degrees. Later, when the room has warmed to 75 degrees, it turns back on again. If we were to run the compressor at 71 degrees, it would be too soon, we’d be constantly starting and stopping. The air conditioner only spits out one temperature of air: really cold. If you run at 71 degrees, by the […]

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