Speaker 1: Brought to you by the reinvented two thousand twelve Camray.
Speaker 1: It's ready. Are you get in touch with technology? With
Speaker 1: tech Stuff from how stuff works dot com. Hello again, everyone,
Speaker 1: Welcome to tech Stuff. My name is Chris Poette and
Speaker 1: I'm an editor at how stuff works dot com. Sitting
Speaker 1: across from me is usual is senior writer Jonathan Strickland Hottown,
Speaker 1: Summer in the city, back in my neck, getting dirty
Speaker 1: and gritty. That was an interesting choice for this episode.
Speaker 1: A little love and spoonful for you guys out there.
Speaker 1: All right. Then, we actually have a little bit of
Speaker 1: business to get to before we jump right into the topic,
Speaker 1: and that is some listener mail. This listener mail comes
Speaker 1: from Ted, and Ted says, I'm a regular listener of
Speaker 1: the podcast and it's been great to listen to on
Speaker 1: my commute to and from my co op this summer.
Speaker 1: I'd like to hear about how air conditioning HVAC units work.
Speaker 1: We design and build them, among other things that my
Speaker 1: co op company, and after helping to put one together
Speaker 1: and tested, I'm still not clear on how it works.
Speaker 1: I would also appreciate an episode about how capacitors work
Speaker 1: in circuits. As a supplement to the article on the
Speaker 1: How Stuff Works site. Lastly, could you talk about Google
Speaker 1: Plus as well as Windows eight. Thanks a lot, keep
Speaker 1: up the good work and good jokes. Ted, Well, Ted,
Speaker 1: We're gonna talk about air conditioners today. But stick around
Speaker 1: because right after we record this, we're recording our episode
Speaker 1: about Google Plus. Yeah, because you know, a couple of
Speaker 1: people have asked for that. Yeah, you'll like a couple,
Speaker 1: I mean, you know. And I plan on scheduling the
Speaker 1: Google Plus episode to publish immediately after this one. So
Speaker 1: if this published on a Monday, look for it on Wednesday.
Speaker 1: If it published on Wednesday, look for it next Monday.
Speaker 1: All right then, because I don't have the calendar in
Speaker 1: front of me. But we're gonna talk about air conditioning units.
Speaker 1: We're not actually gonna talk about h VAC units today.
Speaker 1: We're just gonna talk about air conditioners because there's a
Speaker 1: bit to them. Yeah, there's a bit to them. And
Speaker 1: it's also we in Atlanta right now are in the
Speaker 1: middle of a pretty nasty heat wave. It actually kind
Speaker 1: of broke a little bit. We we have a little
Speaker 1: bit of a break in it right now. It's today, Yeah,
Speaker 1: it's in the it's just it's only in the upper
Speaker 1: eighties with a heat index in the mid nineties today. Yeah,
Speaker 1: but recently we had a heat index over a hundred
Speaker 1: and seven degrees and really high humidity. So in Atlanta
Speaker 1: that was pretty miserable, and a lot of the United
Speaker 1: States has been going through the same thing. This is,
Speaker 1: of course the summer of two thousand eleven from for
Speaker 1: all of you people who are from the future. Uh
Speaker 1: So we thought, you know what, we really appreciate air conditioning,
Speaker 1: So let's talk about how air conditioners work. Yeah, I actually, uh,
Speaker 1: I actually am very grateful for the air conditioning, especially
Speaker 1: this last week. But um. The the answer to to
Speaker 1: the question though, how air conditioners work is sort of
Speaker 1: It's not an easy one because there are different kinds
Speaker 1: of air conditioning. Yeah. Yeah, it's all based on heat exchange,
Speaker 1: but the method of heat exchange differs from one to
Speaker 1: the other, although I would say the majority of them
Speaker 1: use the refrigerant method of heat exchange, where you're compressing
Speaker 1: a liquid and then you are allowing it to boil off. Um.
Speaker 1: But that's a pretty complex issue. Did you want to
Speaker 1: talk about the other types really quickly or should I
Speaker 1: just launch into a science lesson. Well, I think it
Speaker 1: might be a good idea to go ahead and talk
Speaker 1: about the type of air conditioning that most of us use,
Speaker 1: and then maybe look at some of the others. Um.
Speaker 1: I do want to mention a name that is familiar
Speaker 1: to a lot of us, at least here in the
Speaker 1: United States. That would be Willis Carrier. You might say,
Speaker 1: you know, I don't know who that is, Like, oh, wait,
Speaker 1: Carrier made air conditioners. Well he Uh, this was in
Speaker 1: the early twentieth century, so really the modern electrical air conditioner.
Speaker 1: Of course, electricity not being that prevalent until um, you know,
Speaker 1: the late eight hundreds, early nineteen hundreds. UM. Carrier lived
Speaker 1: in Buffalo, New York in the United States, and UM
Speaker 1: he came up with the idea of the do point control,
Speaker 1: which is an air conditioning UH system that basically the
Speaker 1: UH had to do with UH the saturation of cool
Speaker 1: air and UH which you know loses moisture through condensation.
Speaker 1: And that's your science lesson, isn't it. Yeah. Yeah, we're
Speaker 1: gonna have to talk about the relationship between pressure, temperature, liquids, gases, UH,
Speaker 1: and and the It's important to understand this this basic
Speaker 1: level of science in order to really get a grip
Speaker 1: on what an air conditioner is doing, because otherwise I
Speaker 1: could talk about what an air conditioner is doing, but
Speaker 1: you would say, well, why does that work? I know
Speaker 1: how it works, but why does it work? Yeah, we
Speaker 1: do have an article on the side about that, of course. Yeah.
Speaker 1: Actually we have a great article on how air conditioners work,
Speaker 1: and that one was written by Marshall Brain, who was
Speaker 1: the founder of how stuff works dot com. So this
Speaker 1: is it's one of our flagship articles. If you really
Speaker 1: want to see some good animations and illustrations about it,
Speaker 1: I recommend checking that out. But we're gonna talk first
Speaker 1: about well, some basic matter. So we know that matter
Speaker 1: is made up of teeny tiny particles, Yes, you know,
Speaker 1: atoms and molecules. Right, So with solids, this these particles
Speaker 1: are they're not really truly stationary. Okay, these are particles
Speaker 1: are always moving, but in in solids, they're not moving
Speaker 1: a lot, right, Yeah, they're packed closely together. Yeah, they're
Speaker 1: very very dense, and that's why we think of them
Speaker 1: as solid and liquids, not that dense and liquids. Uh,
Speaker 1: they are these particles are allowed to move around, and
Speaker 1: they move around in a more or less random fashion.
Speaker 1: For all we know, it could be a very orderly fashion.
Speaker 1: But it's so orderly, it's like such a complex system
Speaker 1: that we're unable to understand it. So to us, we
Speaker 1: might as well say random. Yeah, well, there's one molecule
Speaker 1: on the side, going okay, keeping keeping mindone, if you
Speaker 1: if you look really closely, you'll see one with those
Speaker 1: little uh those little cones that air track, you know,
Speaker 1: the people on the tar mac use, and they're like,
Speaker 1: all right, coming in, go to the left. It's very
Speaker 1: hard to hold those with your electrons. Yeah, and that's
Speaker 1: why that's why you hardly ever see them. Also, it's
Speaker 1: impossible to know where they are at any one time
Speaker 1: because the uncertainty principle. Uh wow, we're getting really kind
Speaker 1: of crazy with our humor today. So anyway, all right,
Speaker 1: let's let's get serious. So in liquid, these particles move
Speaker 1: around more or less randomly, and some of these particles
Speaker 1: are moving around with with enough energy to break free
Speaker 1: of the surface of that liquid, so they will actually
Speaker 1: become a particle that is in a vapor above that liquid, right,
Speaker 1: all right, like water that evaporates and turns into water
Speaker 1: vapor sort of. But I mean more like water that's
Speaker 1: boiling off. But yes, um, yeah, so the I was
Speaker 1: trying to go for an image that people could Yes, yes,
Speaker 1: very much, very much. So. So the way the way
Speaker 1: you would get one of these particles to do that,
Speaker 1: To get enough energy to break freeze, you have to
Speaker 1: add energy into the system, right. So you when you
Speaker 1: add energy into the system, these particles get more well,
Speaker 1: they get more energy, they start moving around more, and
Speaker 1: then they have they may have enough energy to break
Speaker 1: free from the surface. So if you add heat, that's
Speaker 1: a form of energy, like the boiling water. Right, So
Speaker 1: if you start adding heat to a liquid, more of
Speaker 1: these particles will gain energy and be able to escape
Speaker 1: the surface of that liquid. If you get enough vapor
Speaker 1: so that it actually equals the atmospheric pressure that's on
Speaker 1: top of that liquid, that's when you hit the boiling point. Okay,
Speaker 1: all right, So let's say you've got a pot of
Speaker 1: water at sea level. All right, Now, boiling temperature for
Speaker 1: a pot of water at sea level is two d
Speaker 1: and twelve degrees. Now, what that means is that when
Speaker 1: the water reaches two h twelve degrees, the particles in
Speaker 1: that water have enough energy to escape the surface of
Speaker 1: the water, and the vapor pressure is equal to atmospheric pressure,
Speaker 1: the water will boil and the water will not get
Speaker 1: any warmer than two twelve degrees. You could have that
Speaker 1: fire pumped up as high as it's gonna go, but
Speaker 1: the water temperature will be two hwelve degrees as it's
Speaker 1: boiling off. Now, once the water is boiled off, if
Speaker 1: you have a thermometer in that pot, the thermometer is
Speaker 1: gonna skyrocket, you know, at that point. But the temperature
Speaker 1: the water itself will remain to her and twelve because
Speaker 1: it's actually converting from liquid into gas. So that boiling
Speaker 1: point is in is important to remember. It's it's when,
Speaker 1: like I said, when the pressure of that vapor has
Speaker 1: uh equaled the atmospheric pressure of the environment around it.
Speaker 1: So if you change the atmospheric pressure around that liquid,
Speaker 1: you change the boiling point. So if if the pressure
Speaker 1: is if there's less pressure then it would be at
Speaker 1: sea level, then it's going to take a lower temperature
Speaker 1: to make that water boil. If there is more pressure
Speaker 1: then there is at sea level, then it's going to
Speaker 1: take a higher temperature to make that water boil. All right,
Speaker 1: So let's say that we have put a lid on
Speaker 1: top of that pot. Okay, by putting the lid on
Speaker 1: top of that pot, we have decreased the air pressure
Speaker 1: or the atmospheric pressure on that liquid, so the water
Speaker 1: will boil faster. All right. If you take the lid off,
Speaker 1: then you have just increased the atmospheric pressure. Because now
Speaker 1: more air is actually pressing down that liquid. It's going
Speaker 1: to actually increase the boiling point to its normal boiling
Speaker 1: point at that particular environment. So now we've talked about
Speaker 1: how you have increased pressure, you've increased the temperature of
Speaker 1: the boiling point. Now that's the basics for what we're
Speaker 1: going to talk about with air conditioners. Because air conditioners
Speaker 1: are at least the typical ones you find in houses
Speaker 1: and buildings, use pressure to use to create a pressurized
Speaker 1: liquid that then turns into a depressurized gas. And it's
Speaker 1: a closed loop system. And the liquid in this case
Speaker 1: is a refrigerant, right, so it tends to be some
Speaker 1: sort of of of material that has a boiling point
Speaker 1: that is pretty low. Like it doesn't it's not a
Speaker 1: very high temperature in other words, in normal conditions, normal
Speaker 1: being like in everyday atmospheric conditions that would be a gas. Right.
Speaker 1: So in the one of the common ones we talked
Speaker 1: about is free on, which at this point is more
Speaker 1: or less a generic term, kind of like Xerox or Kleenex.
Speaker 1: Would you know those companies would argue they are not
Speaker 1: generic terms. Yes, they would argue. Their lawyers would argue, yes, certainly.
Speaker 1: But but people use effectively use them, right right, So,
Speaker 1: like I said, I'm going to xerox this, you're you
Speaker 1: talk about, you're making a copy of it, or I'm
Speaker 1: going to Google this. In that case, you may be
Speaker 1: actually using Google, or you may just be using some
Speaker 1: search engine. Kind of the same thing. When people talk
Speaker 1: about free on, unless they're spit talking about the specific
Speaker 1: uh refrigerant, it's more or less just refrigerants in general. Yeah,
Speaker 1: based on my experience recently, I haven't seen the actual
Speaker 1: product free on in quite some time. I think for
Speaker 1: concerns of cfcslora flora carbons. Yes, Um, so I that
Speaker 1: that these days, I don't think free on is used
Speaker 1: very much, if at all, at least not in the
Speaker 1: United States. Um. Of course I could be wrong, but
Speaker 1: there are other refrigerants too, so right, so what an
Speaker 1: air cons what an air condissuer does, is it? It
Speaker 1: pressurizes this refrigerant in one section. Think of think of
Speaker 1: the air conditioner as a closed loop system that has
Speaker 1: a low pressure section and a high pressure section. All right,
Speaker 1: the and the guardians of this, you know, the two
Speaker 1: elements that that separate the low pressure from the high
Speaker 1: pressure are a compressor on one end of the loop
Speaker 1: and a valve on the other end of the loop
Speaker 1: and expansion valve on the other end of the loop.
Speaker 1: These two act as the gateway that keep the pressure
Speaker 1: high on one side and low on the other. All right,
Speaker 1: And it's hot on one side and cool on the other, yes, exactly.
Speaker 1: Because as we pressurize the the refrigerant, the temperature of
Speaker 1: that refrigerant goes up, all right. So the refrigerant, normally
Speaker 1: at at room temperature, would be a gas. You use
Speaker 1: the compressor to compress this gas to a point where
Speaker 1: it's very very dense, and then you run it through
Speaker 1: a series of coils that allow the the this high
Speaker 1: temperature pressurized gas to give off a lot of heat.
Speaker 1: The heat escapes into the ambient. Uh well, that the
Speaker 1: environmental atmosphere. So what the atmosphere has to be of
Speaker 1: a cooler temperature than the the pressurized gas. Right For,
Speaker 1: in order for heat to transfer, it has to go
Speaker 1: from high heat to low heat. You can't have something
Speaker 1: go low heat to high heat. So, in other words,
Speaker 1: if I were to turn on my air conditioner and
Speaker 1: I happened to be in an incredibly hot environment, let's
Speaker 1: say that for argument's sake, it's a hundred and sixty
Speaker 1: degrees outside and my pressurized refrigerant only gets up to
Speaker 1: a temperature of a hundred and forty degrees, that air
Speaker 1: conditioner is not going to work because you are not
Speaker 1: going to have any heat exchange from the actually I'll
Speaker 1: have the wrong sort of heat exchange, but you're not
Speaker 1: gonna have any heat released from the refrigerant into the
Speaker 1: atmosphere because the atmosphere is actually warmer than the refrigerant
Speaker 1: even at its pressurized state. All right, So you've got
Speaker 1: these coils that this heated gas, this compressed heated gas
Speaker 1: is moving through. As it moves through the coils and
Speaker 1: starts to release heat into the atmosphere, that means the
Speaker 1: gas cools. Well. As gas cools, it condenses, and this
Speaker 1: is the process where a gas converts back into a liquid.
Speaker 1: Now it's going to be at a liquid at a
Speaker 1: higher temperature than normally would be because it's under pressure.
Speaker 1: You know, we talked about that the higher the pressure,
Speaker 1: the higher the boiling point. So once you get that
Speaker 1: temperature down below the boiling point of that pressurized substance,
Speaker 1: it condenses into a liquid. This is how we get
Speaker 1: things like liquid liquid hydrogen, with oxygen liquid nitrogen. You
Speaker 1: compress these gases to a very condensed state, compressed state,
Speaker 1: i should say, and it condenses into a liquid, and
Speaker 1: as long as you keep it under pressure, it will
Speaker 1: stay a liquid. If you release that pressure, then it
Speaker 1: immediately starts to boil off and convert into a gas. Well,
Speaker 1: that's the secret. That's the secret of the the valve
Speaker 1: at the end of this loop um the expansion valve,
Speaker 1: because once it the pressurized gas gets to the expansion valve,
Speaker 1: that's what allows it to move into the low pressure
Speaker 1: system and it immediately begins to boil off and essentially
Speaker 1: starts absorbing heat from the environment. Just as it was
Speaker 1: releasing heat when it was going through the condenser coils,
Speaker 1: now it's it's absorbing heat, which means that the surrounding
Speaker 1: air loses heat. It transfers the heat from the air
Speaker 1: into this boiling liquid that's becoming gas very very quickly,
Speaker 1: and then the surrounding air is cooled. That's the basis
Speaker 1: of an air conditioner. Yes, we can actually walk through
Speaker 1: those phases and go into more detail now, but that
Speaker 1: that's basically how it works. It's all about, really you
Speaker 1: have two closed systems. You have the closed system of
Speaker 1: the refrigerant and then you have the closed system of
Speaker 1: the air inside whatever it is you're you're cooling. Because
Speaker 1: you're not pulling air in from the outside environment and
Speaker 1: then cooling it and then pushing it into the building.
Speaker 1: You're recycling the air that's inside the building and it's
Speaker 1: cooling it through the bye bye this heat exchange method
Speaker 1: and just a little bit of h v A C.
Speaker 1: Some systems can reverse it works, and that's called a
Speaker 1: heat pump. I have one on my house, is a
Speaker 1: matter of fact um, which is very convenient. Right In
Speaker 1: that case, you're you're doing the same system, except you're
Speaker 1: you're reversing the process. Essentially, you're recycling the warm air
Speaker 1: inside your house and it's warming it instead of cool
Speaker 1: it YEA and injecting the cooler air outside from the
Speaker 1: process that actually takes place in the unit itself outside
Speaker 1: because if you've ever been outside and next to an
Speaker 1: air conditioner, you've felt you know, it blows hot air outside,
Speaker 1: So you know that, but that's not coming from inside
Speaker 1: the house. That is the result of the process, um,
Speaker 1: and the the exchange of heat. Now, UM Carrier actually
Speaker 1: came up with a system for buildings. He installed one
Speaker 1: in at Grahman's Metropolitan Theater in l a Man's Chinese Theater. Yes,
Speaker 1: I've been there, UM saw the Matrix sequel. It was terrible.
Speaker 1: Theater was great. It was terrible. UM. Yeah. And at
Speaker 1: that point air conditioning was used to uh feed air
Speaker 1: or take air in the ceiling and put it out
Speaker 1: at the floor level, which would be you know, useful
Speaker 1: because the hotter air would be toward the top of
Speaker 1: the room. Um. And the first fully air conditioned office building,
Speaker 1: according to Britannica, was the MILEM Building or MILAM. I
Speaker 1: don't know, it's like M I L A M in
Speaker 1: San Antonio in the United States, and that was built
Speaker 1: in the late nineteen twenties. UM. So again you know,
Speaker 1: this hasn't been forever and ever, but there uh you know,
Speaker 1: it's certainly something that we use and a lot of
Speaker 1: the buildings here down south, especially in these states. But
Speaker 1: there are many, many other types of air conditioning that
Speaker 1: have been going on for years. Do you want to
Speaker 1: get into those yet or do you want to go
Speaker 1: back and get more into the process. Let me, let
Speaker 1: me get more into the process of the typical air conditioner,
Speaker 1: because this is what's going to apply, I think to
Speaker 1: the majority of our listeners who have air conditioning. Yeah,
Speaker 1: so so, and then we can talk about the other kinds,
Speaker 1: including uh, my favorite, the swamp cooler. We'll get into that.
Speaker 1: So let's let's break this down further about the parts
Speaker 1: of an air conditioner. So you've got usually typically of
Speaker 1: an electric motor, and the electric motor you turn earns
Speaker 1: a piston. This this is a very simple compressor. This
Speaker 1: is like the simplest form of a compressor. So not
Speaker 1: all air conditioner compressors are like this, but this, this
Speaker 1: demonstrates the principle. Uh you would call this a piston
Speaker 1: compressor or a reciprocating compressor. So imagine that you have
Speaker 1: a chamber, all right, so a cylinder, let's say, and
Speaker 1: inside the cylinder you have a piston that can move
Speaker 1: up and down the chamber which is sealed, and you
Speaker 1: the electric motor makes the piston go up and down.
Speaker 1: Now at the bottom of this chamber, you have two valves.
Speaker 1: You have a an intake or suction valve that will
Speaker 1: only allow fluid to flow into the chamber through and
Speaker 1: that's that's coming in from the low pressure side of
Speaker 1: this air conditioner system, so it's pulling the the refrigerant
Speaker 1: gas into the chamber. On the other side, you have
Speaker 1: the outtake or the the discharge valve. Is trying to
Speaker 1: think of the right word for it, This charge valve
Speaker 1: would be the right word. So now this valve only
Speaker 1: allows fluid to pass out of the chamber. This pushes
Speaker 1: it into the high pressure side of the air conditioning system.
Speaker 1: So you're pulling from the low pressure pushing into the
Speaker 1: high pressure. And both of these valves are essentially spring loaded, okay,
Speaker 1: so there's a certain amount of pressure, that's a certain
Speaker 1: amount of force that's created by the spring that the
Speaker 1: system has to overcome in order for the valves to
Speaker 1: open in either case. So you've got the piston down
Speaker 1: at the bottom of this chamber, so it's down against
Speaker 1: where the valves are. The piston starts to pull up,
Speaker 1: all right. This this creates an area of low pressure,
Speaker 1: which creates suction. Now, once that force of suction is
Speaker 1: strong enough to overcome the spring force of the intake valve,
Speaker 1: that valve will open. All right. So you're you're you're
Speaker 1: pulling hard enough to overcome the force of that spring.
Speaker 1: The valve opens, and that pulls the free on gas
Speaker 1: in to that chamber. All right. Once the piston gets
Speaker 1: to the top, it stops for a moment that allows
Speaker 1: the spring to close on the intake valve. It is
Speaker 1: now there's no more fluid coming into the chamber, and
Speaker 1: the valve itself is closed. The piston then starts to
Speaker 1: move down. This starts to compress the gas inside the
Speaker 1: chamber eventually create you know, it starts to increase the pressure.
Speaker 1: Eventually that pressure is going to be strong enough to
Speaker 1: open up the discharge valve. The discharge valve opens, and
Speaker 1: that means that the free on gets pushed into the
Speaker 1: high pressure system. You might ask, well, why is that
Speaker 1: high pressure on that system. It's because at the end
Speaker 1: of that side of the air condissuer system is that uh,
Speaker 1: that expansion valve alright, the expansion valve is sort of
Speaker 1: a bottleneck point. And because you keep pressing more and
Speaker 1: more gas into that side and the expansion valve only
Speaker 1: allows a little bit of that gas to escape at
Speaker 1: a time, the pressure increases, right all right. Actually, and
Speaker 1: at that point it's not really gas, it's liquid. But
Speaker 1: we'll get there. So you've got the piston moving, and
Speaker 1: it's moving at an incredible speed. We're talking like a
Speaker 1: thousand rpm, so a thousand repetitions per minute. So when
Speaker 1: I'm talking about this process of the piston coming up, pausing,
Speaker 1: and coming back down, it's doing that multiple times a second,
Speaker 1: something like between seventeen and twenty times a second. Uh. So,
Speaker 1: you're pulling that free on or other refrigerant through the
Speaker 1: low pressure system into that chamber into the high pressure system.
Speaker 1: The this this gas, once it gets pressurized this way,
Speaker 1: it starts to the temperature starts to climb. So now
Speaker 1: the temperature of the freon has increased, that's when it
Speaker 1: starts to move through the condenser coils, and that's when
Speaker 1: it starts to release heat to the environment. Now it
Speaker 1: may release the heat directly to the environment. This is
Speaker 1: why if you were ever to look at an air
Speaker 1: conditioner outside and you see this this series of little
Speaker 1: tubes that are kind of criss crossing, a wiggling back
Speaker 1: and forth across a large surface area. Those are the
Speaker 1: condenser coils. I think of them as metal intestines. There
Speaker 1: you go, do not touch those. They are hot. And
Speaker 1: the reason they are hot just because they're releasing heat
Speaker 1: into that into the atmosphere. If this didn't work, then
Speaker 1: air conditioners wouldn't work. So the heat starts to pull
Speaker 1: off into the atmosphere. Meanwhile, the gas inside those tubes
Speaker 1: that that temperature starts decrease because it's shedding the heat
Speaker 1: off into the atmosphere. The gas starts to condense into
Speaker 1: a liquid. Now, the liquid by the time it gets
Speaker 1: to the the the expansion valve at the end UM
Speaker 1: has reached sort of a moderate temperature. It's no longer
Speaker 1: as warm or as hot as the gas was in
Speaker 1: the in the first part of this condenser coil series. Uh. Now,
Speaker 1: the expansion valve will only allow, like I said, a
Speaker 1: small amount of fluid through at a time, UM, and
Speaker 1: that's what's allowing this pressure to build behind it. Once
Speaker 1: it Once the liquid goes through and it is the
Speaker 1: low pressure system that it's immediately starts to boil, so
Speaker 1: it merely begins to convert into I guess that ends
Speaker 1: up absorbing the heat from the air. And what you
Speaker 1: have is a fan right at that section of the
Speaker 1: air conditioner that blows this now cooled air into the
Speaker 1: building or room or whatever. Okay, So the fan provides
Speaker 1: the air movement so that this cold air can can
Speaker 1: make its way through the building and cool the entire environment. Yeah.
Speaker 1: Without that ability, it would be semi useless. I mean
Speaker 1: it would be yeah, exactly exactly. So you also have
Speaker 1: an intake for to to pull air from the the
Speaker 1: building so that it can be cooled in this section, right.
Speaker 1: So you've got intakes and outakes. You've got the vents
Speaker 1: that are pulling air uh in, and you've got the
Speaker 1: vents that are pushing air out and uh you know,
Speaker 1: depending on you know, a lot of a lot of
Speaker 1: houses I've seen have the intake vents in the floor, right.
Speaker 1: So it's pulling the warm air or it's it's pulling air.
Speaker 1: It's putting cold air at the top to filter down
Speaker 1: into the the um the house, and then it's pulling
Speaker 1: air from the bottom. In order to cool it through
Speaker 1: the system. Right. Well, and if you uh, if you've
Speaker 1: ever stood it right in front of an air conditioner
Speaker 1: vent inside your house, you know that it can be
Speaker 1: quite cold. Um. And it's even colder. And I don't
Speaker 1: mean to say that it would be completely completely useless
Speaker 1: without fans, because my grandmother's house had a window mounted
Speaker 1: air conditioning it um. And of course you know that
Speaker 1: would work just fine, but it wasn't circulating air through
Speaker 1: the house is vents. It actually was you know, sitting
Speaker 1: there in the window and working. Um. And let me
Speaker 1: tell you, standing in front of that thing, uh, it
Speaker 1: is a real blast of very cold air. It's kind
Speaker 1: of it's actually uncomfortably cold. And that's one of the
Speaker 1: reasons why you would want, uh the air to filter
Speaker 1: down in the room like that. It's sort of diffuse
Speaker 1: it with uh the air otherwise in the room and
Speaker 1: sort of make it an it's comfortable a blast of
Speaker 1: cold air, um. You know. But but that's just you know,
Speaker 1: one of those things. And we also, I guess we
Speaker 1: need to add in the fact that air conditioners are
Speaker 1: really useful if you have a thermostat, yes, you don't
Speaker 1: have to have a thermostat. You can have an air
Speaker 1: conditioner that's essentially on or off, but a thermostat what
Speaker 1: that will do is it's essentially a thermometers set with
Speaker 1: a switch. So when a thermometer hits a certain level
Speaker 1: or below, then the switch is turned off and the
Speaker 1: system is shut down. When the temperature creeps up, it
Speaker 1: activates the switch, turns the whole system on, and the
Speaker 1: air conditioner kicks on. So that's that little clicking noise
Speaker 1: you hear is when the temperature and the thermometer inside
Speaker 1: your thermostat, like you've said it to say seventy two degrees,
Speaker 1: and it creeps up to seventy three, that's the thermometer
Speaker 1: then activates the switch. There's you hear the clicking noise
Speaker 1: of the system turning on, and then shortly thereafter you
Speaker 1: should hear the fans system blowing, unless, of course, you
Speaker 1: have a really super quiet air conditioner, which is awesome,
Speaker 1: but then you would start to feel the effects of
Speaker 1: the a C and it happens pretty quickly. Like I
Speaker 1: said this, this is the piston itself is moving in,
Speaker 1: you know, an an incredible speed. So that's your basic
Speaker 1: air conditioner. I skipped over a couple of little things,
Speaker 1: like on the high pressure end, you usually have a
Speaker 1: receiver tank holding tank for liquid refrigerant. That so, once
Speaker 1: it's been pressurized and condensed, it goes into this tank
Speaker 1: and then moves from the tank further into the system
Speaker 1: to eventually get to the valve um. And it can
Speaker 1: get a little more complicated depending upon the nature of
Speaker 1: the compressor. But that's the basic premise of an air conditioner.
Speaker 1: Pretty awesome, really, Yeah, yeah, I know. It's it's an
Speaker 1: ingenious invention. So now that you want to talk about
Speaker 1: some of the alternatives, are you know, different types of
Speaker 1: air conditioners, Well, yes, of course. Um building air conditioners work, uh,
Speaker 1: you know, whole buildings like we're we're actually in an
Speaker 1: office building, a very large office building with multiple floors,
Speaker 1: and you know, you'll often see multiple units, like if
Speaker 1: you fly over in an airplane you look at um,
Speaker 1: like a big box warehouse store or something like an
Speaker 1: office building like the one we're in, you'll see multiple
Speaker 1: air conditioning units on top and condenser towers as well, yes,
Speaker 1: which you know condenser tower Essentially that's just an area
Speaker 1: that is specifically designated for condenser coils. It's to create
Speaker 1: more surface area so that you can have a hotter
Speaker 1: gas pump through those coils, and then the temperature will
Speaker 1: decrease as it goes as it releases a heat to
Speaker 1: the atmosphere. Remember that the temperature of that refrigerant is
Speaker 1: going to vary. It's all gonna depend upon the type
Speaker 1: of refrigerant that's being used, because different liquids boil off
Speaker 1: and at different temperatures UM. And it's also going to
Speaker 1: depend upon the strength of the compressor because the more
Speaker 1: you pressurize that that fluid, the higher that temperature is
Speaker 1: going to be. So if you're using like an industrial
Speaker 1: strength air conditioner, it's probably going to be compressing that
Speaker 1: fluid and using a different type of refrigerant that's going
Speaker 1: to get in a much higher temperature than a home
Speaker 1: unit would have. Therefore, you need more surface area to
Speaker 1: release that heat into the atmosphere and condense it into
Speaker 1: a liquid. What's up home unit? Um? Now. According to
Speaker 1: our article on how stuff works dot com um, a
Speaker 1: lot of larger buildings do use a chilled water system,
Speaker 1: which basically, uh, well, you have a problem with see
Speaker 1: because if you have all those units on the roof,
Speaker 1: then what happens to the people on you know, and
Speaker 1: let's say a fifteen story building, Uh, what happens to
Speaker 1: all those people on the second floor, a third floor,
Speaker 1: because that's a long way to go. So what they
Speaker 1: do is essentially they they uh and in a oversimplification
Speaker 1: as I'm want to do on this show, basically, they
Speaker 1: transfer the the cooling effect to water and then the
Speaker 1: chilled water is pumped through the building. UM and uh,
Speaker 1: you know that's just that's just the basics. Um. But
Speaker 1: um apparently takes water down to between around forty and
Speaker 1: forty five degrees fahrenheit, which is four point four and
Speaker 1: seven point two degrees celsius. And it's just you know,
Speaker 1: connect they pump the chilled water through and it and
Speaker 1: it goes to those are connected to air handlers. Um.
Speaker 1: And these are closed systems. Yeah, and you have to
Speaker 1: you have to insulate those pipes too, because otherwise the
Speaker 1: uh you know, cold water inside the pipes, um, they
Speaker 1: will lose their coolant to you know, as they travel
Speaker 1: throughout the building around. So you can't really do that.
Speaker 1: But um, yeah, there are also some ice systems where
Speaker 1: you essentially what you do is you have an enormous
Speaker 1: tank on the top of a building. This really works
Speaker 1: for for large buildings, not for houses. But you would
Speaker 1: have a a storage tank that would hold water. You
Speaker 1: would freeze that water at night when electricity rates are lower,
Speaker 1: so it's more it's not gonna cost as much to
Speaker 1: UH to actually freeze it. But you freeze that water,
Speaker 1: and then in the daytime as the water as you've
Speaker 1: got this big old block of ice, you have fans
Speaker 1: blow air against the ice, which creates this chilled air,
Speaker 1: that conditioned air that you can then can circulate either
Speaker 1: through the building or you use it again to chill
Speaker 1: another water line that circulates through the building and thus
Speaker 1: cools the building. UM. This is a pretty inexpensive way
Speaker 1: to create air conditioning once you've got the system in place.
Speaker 1: But putting the system in place is quite expensive, indeed,
Speaker 1: because you're talking about building a pretty enormous tank and
Speaker 1: it's it's it's not cheap to build, but once it's there,
Speaker 1: it tends to be less expensive than running a conventional
Speaker 1: air conditioner. And of course, down at Turner Field here
Speaker 1: in Atlanta, which is where the Atlanta Braves baseball team plays, UM,
Speaker 1: there's a space outside where UM they spray water and
Speaker 1: the fans can walk through that area and it you know,
Speaker 1: you don't get I guess you get a little damp.
Speaker 1: But the effect is the cooling effect because it's you know,
Speaker 1: they atomized water feels you know, it's it's sort of
Speaker 1: like sweat actually when you know, when it evaporates, it
Speaker 1: makes you feel better. Well that they used to, uh,
Speaker 1: they used to do that in the nineteenth century textile industry, um,
Speaker 1: because they were using it for humidification and cooling purposes.
Speaker 1: According to Britannica UM. But in India a long time ago,
Speaker 1: they used to hang wet grass mats over their windows,
Speaker 1: basically doing the same thing. It was the evaporating water
Speaker 1: would uh would cool down the room, it cools down
Speaker 1: the surrounding air. Um. Because again, the in order to evaporate,
Speaker 1: the water needs energy. So the water is taking energy
Speaker 1: from the air around at the heat from the air
Speaker 1: around it, and then you have air that has it's cooler.
Speaker 1: It's the heat has been transferred to the water utter um. Yeah,
Speaker 1: Benjamin Franklin actually looked into this as a way of
Speaker 1: cooling systems and uh, he kind of figured it out
Speaker 1: as well. And you know, it's been. It's been in
Speaker 1: use for millennia. Ancient Egyptians have been doing this, you know,
Speaker 1: Well ancient Egyptians aren't doing it anymore. They're not doing
Speaker 1: much of anything other than, you know, hanging out in museums.
Speaker 1: But anyway, the which I do too, but I'm actually
Speaker 1: a little more lively anyway, I'm getting off track again,
Speaker 1: thank you. So this actually brings us to what I
Speaker 1: had mentioned earlier, the swamp coolers. So swamp coolers work
Speaker 1: on this system. And you might wonder why they're called
Speaker 1: swamp coolers. Well, it's probably because they can smell a
Speaker 1: little swampy if you don't maintain them properly. They actually
Speaker 1: do not work very well in humid environments, and I'll
Speaker 1: explain why in a minute. The process of a swamp
Speaker 1: cooler is kind of interesting. What essentially what you're doing
Speaker 1: is you're pulling warm air from outside. You're blowing that
Speaker 1: warm air through a a chamber that has usually moist
Speaker 1: pads in it. So you've got like some sort of
Speaker 1: padding material that has water. Um, it's soaked with water.
Speaker 1: The warm air causes the water to evaporate. In that process,
Speaker 1: the air itself loses some of its heat and then
Speaker 1: uh a fan blows the cooler air into the environment,
Speaker 1: into the house or whatever. Now, this is different from
Speaker 1: an air conditioner in several ways. One of them is,
Speaker 1: like I said before, an air conditioned system and is
Speaker 1: a closed system, not just from the free on but
Speaker 1: also the air inside the building. If you open up
Speaker 1: a window or open up a door inside an air
Speaker 1: conditioned house, you know, you'll you'll hear like your mom
Speaker 1: will yell, you're letting out all the air conditioning. Well,
Speaker 1: that's that's actually true because what it's doing, because it's
Speaker 1: recycling the air inside that system. So if you open
Speaker 1: up stuff, it's you're losing that that uh you're you're
Speaker 1: causing the air condition to work harder in order to
Speaker 1: try and get to the right uh temperature. Also, what
Speaker 1: were you raised in the barn? Right? Do you think
Speaker 1: we're air conditioning the whole neighborhood. Uh So a swamp
Speaker 1: cooler though, it's pulling air from outside and pushing it
Speaker 1: into the environment, So you actually have to have a
Speaker 1: window or door open or to have air circulation, otherwise
Speaker 1: you're just pumping air into a house until it explodes.
Speaker 1: It's not entirely true. Not entirely. Yeah, it doesn't actually
Speaker 1: have it that way, but you have exactly. Man reminds
Speaker 1: me of my house. But anyway, you have to you
Speaker 1: have to open up a window really to have this
Speaker 1: be effective. So it's pulling this hot air from the environment,
Speaker 1: pushing it through a chamber that has these moist uh
Speaker 1: padding things inside of It depends on, you know, the
Speaker 1: kind of swamp cooler exactly what form it makes, but
Speaker 1: pads moist pads um evaporates the air, cools, the evaporates
Speaker 1: the water cools the air, and then the cooler air
Speaker 1: polls is pushed in through by a fan into the
Speaker 1: into the house or whatever. Now this only works in
Speaker 1: really dry and ironments, and the reason for that is
Speaker 1: that the temperature of the air is going to be
Speaker 1: different between the regular dry bulb air, which is the
Speaker 1: temperature of the air as it is, and the wet
Speaker 1: bulb air, which is the temperature of the air if
Speaker 1: it were a humidity all right. So the greater that difference,
Speaker 1: the more a swamp cooler will cool a building. So
Speaker 1: if you're in a very dry spot, let's say Las Vegas.
Speaker 1: Las Vegas is pretty dry, the difference between the air's
Speaker 1: temperature at its normal state, and the air's temperature if
Speaker 1: it had a humidity will be pretty large. Yeah, then
Speaker 1: using a swamp cooler means that that difference in temperature
Speaker 1: will essentially result in a cooling effect. They can get
Speaker 1: a house down to around say seventy two degrees, which
Speaker 1: is a comfortable temperature for most people. Now, if you
Speaker 1: were in a very high humid area like say, I
Speaker 1: don't know, Atlanta, Georgia, where the humidity can be or radar,
Speaker 1: the difference between the dry bulb air, which let's say
Speaker 1: it's at that eight percent humidity, and the wet bulb air,
Speaker 1: which is a percent humidity is small. The difference is
Speaker 1: not significant really, and so you are not going to
Speaker 1: get a big cooling effect from a swamp cooler. You
Speaker 1: may just feel like, oh, the hot air in my
Speaker 1: house is being replaced by slightly less hot air coming
Speaker 1: from this cooling system. That's not not more comfortable, it's
Speaker 1: just not as hot. So swamp coolers can work great
Speaker 1: if you are in a very dry place, a dry,
Speaker 1: hot place, um, and if you're in a stifling hot,
Speaker 1: wet place like like most of the southeast most of
Speaker 1: the Eastern seaboard. Really in the United States, I should say, yeah,
Speaker 1: there are many other places around the world that would
Speaker 1: have similar problems. Yes, yes, this is true. It's not
Speaker 1: just us. It's just easy for me to talk about
Speaker 1: because I have a lot of experience on the East
Speaker 1: Coast the United States of America. Um, swamp coolers are
Speaker 1: not the best choice for you, Yeah, they're there are
Speaker 1: problems with I mean, my father told me about someone
Speaker 1: he knew who tried to essentially a modernized version of
Speaker 1: the grass matt technique. And you know, blowing air through
Speaker 1: your house in a high humidity climate when you've been
Speaker 1: you know, pumping water down this you know surface, basically
Speaker 1: you're just adding more humidity and it's closed off, which
Speaker 1: makes mold and mildew a problem. Yeah, and it's yeah,
Speaker 1: there's also that there isn't with regular air conditioning. My
Speaker 1: basement is the top floor of my house is you know,
Speaker 1: pretty decently comfortable, but downstairs is like a meat locker.
Speaker 1: And uh, we actually run a d humidifier in the
Speaker 1: summer because it can get sort of musty down there.
Speaker 1: So yeah, and uh, really, when you when the air
Speaker 1: is saturated with water, I mean we're talking about a
Speaker 1: hundred percent humidity. When the air is saturate with water,
Speaker 1: then you're not going to add more water to that system.
Speaker 1: So that's why the swamp cooler won't be effective at
Speaker 1: that point. It's also why if you are in the
Speaker 1: southeast of the unit It States and it's a very
Speaker 1: humid day, you might start sweating, but you don't feel
Speaker 1: any cooler because the sweat is not really evaporating off
Speaker 1: your skin. It's just accumulating because the air is already
Speaker 1: so saturated with moisture. That's that you can't you can't
Speaker 1: add to it. That makes me feel even warmer, right right.
Speaker 1: That's why you will often hear the phrase it's not
Speaker 1: the heat, it's the humidity, and then you immediately punched
Speaker 1: that person out. It's uously followed by vio. I have
Speaker 1: been punched in the face many times. When I've talked
Speaker 1: to my friends out west. We're like, yeah, well, it's
Speaker 1: a hard or fifteen degrees out here in Texas, And
Speaker 1: I said, well, it's you know, only degrees here, But
Speaker 1: you know it's not the heat, it's the humidity in Texas.
Speaker 1: They like to punch yeah, yeah, cattle. Sometimes I end
Speaker 1: up sometimes Jonathan, It's it's terrible. I mean it's just
Speaker 1: blood and barbecue sauce everywhere. It's it's a horrible thing. Anyway,
Speaker 1: that's all I have. Do you have anything else you
Speaker 1: wanted to add before we kind of wrap this up? Nope? Cool, Well,
Speaker 1: well I did not. Yeah, that was totally unintentional. Guys,
Speaker 1: that was well. First of all, Ted, thank you so
Speaker 1: much for that request. That was great. We had a
Speaker 1: fantastic discussion. We talked about one of our really cool
Speaker 1: articles on the site. Like I said, if you guys
Speaker 1: want to learn more about this, go find how air
Speaker 1: conditioners work at how stuff works dot com because there's
Speaker 1: a great article on that, and and really this is
Speaker 1: one of those things that we a lot of us
Speaker 1: take for granted, but it is a pretty cool application
Speaker 1: of science and technology, and I thought it was a
Speaker 1: really nice topic to tackle. So thanks a lot. If
Speaker 1: you guys have any suggestions for topics that you would
Speaker 1: like us to talk about, you can let us know
Speaker 1: an email. Our address is text stuff at how stuff
Speaker 1: works dot com, or contact us on Facebook or Twitter
Speaker 1: and the handle there is tech stuff h s W.
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