Air Conditioning!
What an adventure, who knew getting an air conditioner would be so complicated?
There are two main parts to a central air conditioner. Outside the house is the compressor, usually a large beige box, and inside the house is the coil, literally just a coil of copper tubing attached to the furnace. How AC works is so ridiculously simple that it's borderline unbelievable. Basically, you have a working fluid (like Freon) that is expanded by forcing it through a small constriction and then into the coil. As the liquid is forcibly expanded, it cools down dramatically. The furnace then blows air over the cold coil, cooling the air, which is then pushed out of vents throughout the house.
After the working fluid reaches the end of the coil, it has absorbed a significant amount of heat from the air inside the house. It is then returned to the compressor outside, which, oddly enough, compresses it back into a liquid. The heat garnered from the house and produced during the compression step are left outside.
Obviously, in practice it's a bit more complicated. Specifically, the compressor is a fairly involved piece of equipment. But still, the fact that the whole system boils down to (uh, no pun intended) air being forced over a cold pipe amazes me.
Now, air conditioners come in different sizes and different levels of efficiency. The sizes are measured in half ton (6,000 BTUs) increments starting at 1.5 tons. The unit 'ton' apparently comes from the fact that it takes 12,000 BTUs (British Thermal Units) to melt one ton of ice. Seriously, you can't make this stuff up. The efficiency is measured in the Seasonal Energy Efficiency Ratio (SEER). The federal government currently requires all units sold in the US to be at least 10 SEER, but starting in January 2006, all new units must be at least 13 SEER. Some companies claim to have units that weigh in at as much as 18 SEER.
Now, we have a very small house. Even so, every single estimate we got, save one, recommended a 2 ton unit for house. And ever single estimate we got, save one, simply used the rule of thumb that says 1 ton for every 500 sq ft. The last company (20th Century) actually ran the necessary heat load calculations for our specific house and found that 1.5 tons was easily enough for us. And that unnecessary half ton saved us a lot of money. And apparently, these companies are not aware that every single piece of AC advice on the net screams that you should NEVER hire any company that doesn't bother to do heat load calculations.
The unusual thing--I thought--was that it was really hard to get any of them to sell me a unit more efficient unit then a 10 SEER. We finally got a 1.5 ton, 12 SEER unit made by Armstrong. It would have cost us another $500 to move up to a 14 SEER (the next highest they make). Guess they're just trying to liquidate their old stock.
-Tim
There are two main parts to a central air conditioner. Outside the house is the compressor, usually a large beige box, and inside the house is the coil, literally just a coil of copper tubing attached to the furnace. How AC works is so ridiculously simple that it's borderline unbelievable. Basically, you have a working fluid (like Freon) that is expanded by forcing it through a small constriction and then into the coil. As the liquid is forcibly expanded, it cools down dramatically. The furnace then blows air over the cold coil, cooling the air, which is then pushed out of vents throughout the house.
After the working fluid reaches the end of the coil, it has absorbed a significant amount of heat from the air inside the house. It is then returned to the compressor outside, which, oddly enough, compresses it back into a liquid. The heat garnered from the house and produced during the compression step are left outside.
Obviously, in practice it's a bit more complicated. Specifically, the compressor is a fairly involved piece of equipment. But still, the fact that the whole system boils down to (uh, no pun intended) air being forced over a cold pipe amazes me.
Now, air conditioners come in different sizes and different levels of efficiency. The sizes are measured in half ton (6,000 BTUs) increments starting at 1.5 tons. The unit 'ton' apparently comes from the fact that it takes 12,000 BTUs (British Thermal Units) to melt one ton of ice. Seriously, you can't make this stuff up. The efficiency is measured in the Seasonal Energy Efficiency Ratio (SEER). The federal government currently requires all units sold in the US to be at least 10 SEER, but starting in January 2006, all new units must be at least 13 SEER. Some companies claim to have units that weigh in at as much as 18 SEER.
Now, we have a very small house. Even so, every single estimate we got, save one, recommended a 2 ton unit for house. And ever single estimate we got, save one, simply used the rule of thumb that says 1 ton for every 500 sq ft. The last company (20th Century) actually ran the necessary heat load calculations for our specific house and found that 1.5 tons was easily enough for us. And that unnecessary half ton saved us a lot of money. And apparently, these companies are not aware that every single piece of AC advice on the net screams that you should NEVER hire any company that doesn't bother to do heat load calculations.
The unusual thing--I thought--was that it was really hard to get any of them to sell me a unit more efficient unit then a 10 SEER. We finally got a 1.5 ton, 12 SEER unit made by Armstrong. It would have cost us another $500 to move up to a 14 SEER (the next highest they make). Guess they're just trying to liquidate their old stock.
-Tim
posted by tjmcardl | 9:29 PM
1 Comments:
Yeah, well, I hear that Freon is pretty nasty stuff. And our house may be small, but peltiers?
-Tim
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