Where SEER Goes Wrong?

We use a Seasonal Energy Efficiency Ratio to get a vague idea of how well a system performs, but what if the test is rigged? A few years ago, word came out that several major manufacturers had been cheating on their emissions testing. What if the same problem goes on in the HVAC world? An Old Standard In the United States, there was no legislation on SEER until the late 1980s. It didn’t take effect until the 90s. That’s a good thirty years or so for the world to change. The testing for SEER is done at 80 Degrees indoor temperature, against a variety of outdoor temperatures up to 105 degrees. That sounds like a balanced test, but it has its flaws. The test results are weighted, giving more value to a milder summer, with a focus to highs in the 80s and lower humidity. We don’t necessarily experience such results today. We might hit highs in the 90s in much of the US, have higher humidity, and often want our thermostats set in the 70s. These testing conditions are even more out of line for places like Arizona, where the 105 degree day is the standard experience. The SEER gives you a great comparison between machines, but it doesn’t give you a true picture of what to expect on your bill. Loss of Performance There are also concerns that the testing doesn’t truly cover how the changes in temperature […]

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What is SEER?

When shopping for AC, you’re going to see a few strange numbers: EER and SEER. These are you Energy Efficiency Ratio and your Seasonal Energy Efficiency Ratio. We use these to understand how well a given air conditioner performs, how much power does it take to keep you cool.   Getting the Ratio The math behind an EER ratio is pretty straight forward: BTU/Watts. This is essentially miles per gallon, but for an air conditioner. You could think of it as coolness per watt. For example, we could have a theoretical 6000BTU window unit that draws 300 watts. 6000/300 gets us 20. It’s just another number, right? The useful factor comes in with comparison shopping. We know that particular unit is going to be extremely efficient. The manufacturers already do the calculations for us, so it’s just a matter of finding the EER rating on the box or online documentation. We can look around other units, and maybe we’ll see a few 21’s, maybe some 18’s and probably quite a few cheaper units with a 13 EER. The rule of thumb is to go for the highest EER you can afford, as it will save you more money later. That does however, beg the question of how much money. That does require some extra math. Machine 1 has an EER of 20. It runs on 300 watts. 300 x 24 hours = 7200 watts for 1 day of continuous use. […]

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Why Are There So Many Fins in a Coil?

If you look really close at your air conditioner’s evaporator or condenser coil, you’ll see a ton of tiny fins sandwiched between two tubes. You might ask yourself, why are we making this so fragile. A screwdriver could puncture these fins with just the smallest bit of force, let alone what some ice could do. Why are we using such tiny parts instead of just a few, massive fins or something more robust?   Old Radiators Let’s start with a trip to the past: the classic heating radiator. A radiator like this is just another type of heat exchanger, almost the same thing as your air conditioner’s coils, but designed to heat the home or office. These were massive, robust pieces of equipment. They weighed hundreds of pounds of cast iron and could break your foot, leg, and back all at once during a botched installation. These work on the same principle as other heat exchangers: we change the temperature of the heat exchanger, and it in turn changes the temperature of the air. With such beefy components though, it requires a lot of water or steam to make any significant changes. Sure, the radiator will get hot enough to fry an egg or reduce just about anything to a piece of charcoal, but it doesn’t have a lot of contact with the air. It ends up being slower as a result.   Surface Area When we radiate or absorb […]

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How to Tame Your Cooling Costs

Air conditioning is expensive, but essential for most of the world except perhaps the arctic circle. It improves employee productivity and attracts customers on the hottest of days. Unfortunately,  it also makes an electric meter look more like a helicopter, buzzing along as we suck down ever more watts in search of comfort.   The Little Things Use light-colored windows blinds and curtains. Every place that light gets into your building is some place it’s going to raise the temperature. Light ultimately creates heat, the sun is giant, nuclear, laser ball. If we can make sure its light falls on reflective things, like lighter colors, curtains and blinds, we can reduce the amount of heat generated inside the room. It would be impractical to close off grand entry ways with curtains, but everywhere else is probably fair game. Even some window blinds in the office can reduce the heat coming in by half, while still keeping the room fairly bright for your staff. Dial back the temperature The greater the temperature difference, the harder the air conditioner has to work to maintain that difference. Remember that you need to only create apparent comfort. If it’s 100 degrees out, your employees and customers will probably be grateful for anything less than 85 degrees. You don’t need to make the office 60 degrees. Close the doors Ensure you’re not venting cool air wastefully. Keep the doors closed or install a closing mechanism […]

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Why Do Fans Make Us Cooler?

Good Monday Morning everyone. We’re going to kick off this week with SCIENCE! Specifically we’re going to look at fans and the reason they can cool us down (but not always). Fan In a Box Let’s start with simple science. Can a fan physically cool a room? We can’t rely on our senses for this, we need actual, concrete numbers. As we covered last week, we can trick the senses into feeling cooler with well designed environments. People make for very poor thermometers. For our experiment, we’ll put a fan in a plastic box with a temperature sensor. We’ll also monitor the room for any changes in temperature. We’re going to discover something very important, very quickly: the temperature inside the fan box steadily increases when the fan is on, and the room temperature remains constant. We can discern two important facts from this: Fans do not create cool air or change the temperature of the air on their own. Fans contribute heat to the environment. The heat is easy enough to explain. The fan contains copper windings for a motor and there are spinning parts. Whenever something moves, it experiences friction. Whenever we pump electricity into something, there’s a certain amount of it lost to the environment. The fan creates heat as a matter of functioning. Let’s try something else. We’ll take a computer fan, and put it through a little home-made duct to blow over the tip of […]

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Outdoor Air Conditioning?

It’s summer. It’s hot and humid and we’ll do anything to ease the heat off, even a little bit. Or in some cases, we’ll do anything to ensure our guests, customers, and clients don’t melt just for coming to a major public event. The problem is, how do we cool people down outside? It can’t be that hard, right?   Mother Nature’s Onslaught We first need to understand what we can’t do. On a hot sunny day, there’s effectively hundreds of thousands of BTUs of heat in the air. If we attempt to use a standard air conditioner outside, it’d be every bit as effective as blowing in the wind or using a match to solder 6″ piping. We’re fighting an uphill battle. Modern air conditioning works because we can keep it inside. Air naturally wants to mix and achieve a temperature equilibrium. By putting cool air into buildings, we contain it and prevent any significant dispersal from occurring. Our 40,000 or 400,000 BTU of cooling is able to actually get something done in this way. We could put these massive machines outside and try, but chances are they would have to remain constantly on. Even if a target temperature could be reached, the movement of the air would soon blow our nice, coolness away. It quickly becomes a matter of impracticality. The size, cost, and logistics of the cooling equipment to cool your company picnic or cool an entire […]

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Destructive Dirt and Debris

Your air conditioner has an enemy, a nemesis to rival dirty air filters. Dirt, Debris, and overgrown plants are the outdoor equivalent of dirty filters. It is essential that your condenser gets as much undisturbed airflow as possible. That means no dirt on the coils, no bushes blocking off its sides, and no leaves piling up around it.   Why Is This a Big Deal? Your air conditioner essentially collects heat from inside your building and then radiates it into the air outside the building. This has a few prerequisites: lots of air, lots of thermal-contact with the air, and ideally lots of airflow to replace the heated air with fresher, cooler air. The condenser was designed to provide all of these things. There is a fan to suck in more air. There are thousands of tiny metal plates weaved back and forth inside the coils. These coils are made extremely conductive metals that will help radiate heat into the atmosphere. Things go downhill fast when you start interfering with these features. Dirt is especially a vicious enemy here. The metal of the condenser coil is an amazing thermal conductor, readily blasting heat into the atmosphere. Dirt however, is not a good thermal conductor. Most dirt is going to act more like an insulator and reduce the amount of heat that flows from the condenser coil into the air around it. Less heat-flow means less capacity. Your 39,000 BTU system […]

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The Most Important AC Maintenance Item

In large part, modern HVAC systems are nearly maintenance free. We don’t mean that they don’t break down, we mean that you don’t have to get oil changes, rotate your tires, refill the blinker fluid, or anything else particularly special, they just work except for the occasional breakdown. That is except for the one, final frontier in user maintenance. There is one, absolutely essential thing you must do if you use an air conditioner.   CHANGE YOUR AIR FILTER   I’d have made that blink and flash, but the boss took my keyboard away until I agreed to stop putting neon-signs in the blog. Time after time after time, people ignore that blinking little light that says “change your filter.” This is a bad thing. We get it filters are expensive. They’re big and bulky, so they cost us more to ship in and out, and you always have to drag yourself to the supply room and mess with things to replace them. Nobody wants to sit around, changing filters, but you need to.   Effects of Dirty Filters There are three main problems with dirty filters: they stink, they can lead to mold, and they block airflow. With a gross enough filter, no one will want to be in the office, your customers will run away, and some poor sap is going to change it wearing rubber gloves and a home made hazmat suit. Once an air filter reaches […]

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It’s 50 Degrees Out, Why Do I Need AC?

Every now and then we get asked a question and realize, “the truth is not as straight forward as it seems.” Or “there is a lot more at play here.” Today, that question focuses on why we need to flip on the AC, despite it being perfectly cool outside our homes. The Environment It’s late Spring in Pennsylvania, quickly approaching Summer. Our daytime highs range anywhere from 68 degrees clear to 92 degrees right now and this is considered the ‘cool’ part of the season before things heat up. At night, the lows can range anywhere from 48 to 62 or so for now. This is just pleasant weather. We don’t necessarily think about the air conditioner much yet. Take off your sweaters and you’re going to be pretty comfy outside. The same however, is not necessarily true for inside the house. Despite it being merely 65 degrees outside, and the heater having sat quietly off all night long, my house was already 80 degrees this morning. We had windows open and fans running to suck in the outside air, but the house was still roasting inside. Trapped Heat The first culprit for all this heat is a key part of any efficient building: insulation. My house, like most others will do its best to resist losing heat. There’s thick insulation in the walls and as we’ve covered before, it works well. Whatever thermal energy is in the house, is […]

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What’s the BIG Problem with my AC?

Every season there will be a fair number of people with small problems in their air conditioners. They’ll experience leaks, failed belts, and maybe a few minor electrical issues. These are all little wear and tear things that your contractor can fix for a few hundred dollars. When an air conditioner gets older however, things start getting a little more expensive. There can be some big things starting to fail.   Dead Compressor The compressor is that big, typically black, cylinder or spherical object in your air conditioner. In many ways it is the heart of the system. The compressor will receive refrigerant and through one of many ways, squeeze it down. This compression is what lets us remove heat from the air elsewhere in the system. When the compressor fails or begins to fail, you might experience warm air blowing from the air conditioner instead of cold air, regardless of temperature setting. The system may have difficulties starting up, draw excessive power, burn through fuses, or trip its breaker. When the compressor fails, there’s really only two areas things can go wrong: the motor or the compressor assembly. If the motor starts to go, it’ll perform poorly and draw more power to start and run. Eventually the motor will just get hot and stop cranking the compressor assembly altogether. At that point, it’ll probably blow a fuse and start melting internal components. On the other hand, there’s also a […]

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