TechStuff Goes to the Ice Rink

Market where we have an ice rink. Now, now, when I actually had this conversation, the ice rink had not been completely installed. There was a distinct lack of ice, for example. But it got me to thinking about doing a full episode about the technology then makes ice rinks possible in areas where it is not below freezing. I mean, obviously, you can have a natural ice rink if you happen to live someplace where it gets cold enough for a pond to freeze through thick enough where it's safe to

do that. But as for indoor ice rinks like hockey ranks and ice skating rinks in general, you have to have a system there in order to make it work, So that's why I'm really going to explore today. Now, I'm not really familiar with this from a personal level, and that's because I live in Atlanta. I grew up essentially in the Atlanta area. I am a Southerner. We are not well known for our winter sports. We did once upon a time have an NHL hockey team called

the Thrashers that got sold off to Winnipeg. But I'm not going to spend this entire episode grousing about how we don't have the Thrashers anymore. I could do that, but I won't. We do have a few temporary ice rink seasonal ice rinks that pop up during the winter, though, and I've never actually been on an ice rink. The closest experience I've had would be roller skating, and that's obviously similar but not the exact same thing as ice skating.

But I do know I'm terrible at roller skating. I mean, absolutely, hilariously not graceful on roller skates, so I'm pretty sure i'd wipe out instantaneously on an ice skating rink. But I did want to learn more about how those are created and how they're maintained, particularly in places like here in the South where we have some of these outdoor

ice skating rinks. And in case you weren't really familiar with us, our temperatures rarely dip below freezing, so it takes a lot of engineering to make sure that ice rink stays nice and icy. The tech to make an ice rink is pretty cool, pun intended, and a big component of it is essentially the same sort of tech that makes refrigerators or air conditioners work, only on a way bigger scale, but the same basic principles apply. So we're gonna talk a lot about the refrigeration cycle, and

we're gonna talk a lot about heat exchangers. But first let's get some basic physics under our belts. Now, we've got to talk about thermal physics, as in the physics that are all about heat, and heat itself is a physical process. Heat is not something that is necessarily possessed. Heat is technically the transfer of energy from something of a high temperature to something else of a lower temperature.

That process, that exchange, is in fact heat. So a lot of this stuff i'm gonna talk about you've probably heard plenty of times in basic science classes. But if you're like me and may have been a very long time since you've had a physics class, and you might need the refresher. And I always feel it's important to start simple and then you build from there. So first things first, heat always moves from an area of high temperature to an area of lower temperature within a system.

That's how you do not have heat move from low temperature to high temperature. That would be crazy. It only goes high to low. That's just how our universe works.

You cannot transfer the other way around. So any object that has a higher temperature than its surroundings within a system will gradually transfer heat to those surroundings and its own temperature, assuming there's not something actually generating the heat within this object will decrease until both the object itself and its surroundings will reach an equilibrium, that meaning they

reach the same temperature. Similarly, if you have an object that has a lower temperature than its surrounding environment within a system, it will gradually warm up. Now this is not to say that cold is leaking out or escaping. Cold does not transfer. Only heat transfers. Heat from the environment moves into the object, ject gradually increasing its temperature.

Until again it reaches an equilibrium. Now, in the real world, we would typically call this room temperature, because the systems we operate in on a day to day basis are these rooms and basic environments. So if you have a hot cup of tea and you leave it sitting on the counter for several minutes, it starts to cool because it's releasing that heat. That heat is transferring to its surrounding environment that is at a lower temperature than the

hot cup of tea. Uh. Likewise, if you have a nice frosty beverage and you leave it on the counter, it will start to warm up. It'll start to absorb heat from its environment as it transfers in, until again it reaches that equilibrium. From a macro level, we could say that the heat is this flow of energy, So just keep that in mind. Generally speaking, if you want to make the base of an ice rink colder, technically this works for anything, but we're gonna use ice rink

specifically because that's what this episode is about. If you want to make the base of an ice drink colder, you have to expose it to something that has a lower temperature than the rink base. So here in Atlanta, it's in I think the low sixties right now on fahrenheit, and we want to get the temperature of the base of that ice rink below the freezing temperature of water,

which in fahrenheit would be thirty two degrees. It means that we have to expose that base of the ice rink to a temperature that's actually significantly lower than the freezing point for water in order to make this happen. Then the rink base will transfer heat to that lower temperature object, in other words, whatever we're using to cool down the base. Technically, what's happening is that the base is actually transferring heat to that system, and thus it

will grow colder. Now, on principle, that's pretty simple, right, It's not a very amplicated thought. You just have to get something that's colder than what you're working with and move them within the same system, and then it will gradually make the other thing colder because they'll start to absorb the heat from that other thing. That's not that complicated. But then when you start actually looking at practical applications, you realize, all right, we've got to solve some pretty

big problems. Requires a lot of engineering So, for one thing, if you want the ice rink to remain ice even if the surrounding temperature is above the freezing point for water, for example Atlanta, Georgia, and the winter tends to be that, you'll have to continuously chill the base of that ice rink. You can't just get it cold and leave it. You have to keep it cold. And since the base of the ice rink will continually transfer heat to that colder object,

that colder object will eventually warm up. So whatever the system is that you're using to chill the base of the ice rink, it's absorbing heat. That means it is warming up. That means you have to have a continuous way to to keep that that's system more cool, to chill it, to use a chiller if you will, that's what they're called. Uh So these are actually pretty complicated. Now. I keep saying colder object because not all ice rinks are equal. They're not all exactly the same. They use

the same principle, but the actual application is different. So, for example, if you wanna hockey rink, like a standard hockey rink in HL hockey rink, you're talking about typically a a base. There's a concrete base under which you have a network of steel pipes, and the steel pipes carry an extremely cold liquid, something that's below the freezing temperature of water. We'll get into that a little bit later, and that in turn pulls heat away from the concrete base,

making it colder than the freezing point for water. You can then add water on top of the concrete base and start building up layers of ice. Others are a little bit different. The one that's up on the rooftop of our building actually has a series of plastic tubes that are carrying an extremely cold liquid in them being pumped underneath the surface of the ice rink, and that's what allows the water to freeze even in temperatures that

are above the freezing point for water. And essentially pour water on top of this or otherwise distribute water on top of it. It's a little more precise than just pouring, and you get your ice rink. Uh So, generally speaking, same approach, just slightly different applications. Now we have to create a system that will hold a temperature below the freezing point of water. Now that presents itself with a few challenges. First, you have to figure out, all right,

what substance are we going to use. Clearly, we can't just use plain old water because if we did the water in our system to try and absorb heat, that would freeze and then you wouldn't be able to move it through your pipe system. So you can't just use plane old water. You would need to have a liquid that has a lower freezing temperature than water does. So one way you could do that is by adding stuff to water in order to lower its freezing point. So

salt is a good example. Saltwater has a lower freezing point than freshwater, and that freezing point is dependent upon how much salt concentration there is within that water mixture. So some hockey rinks will use a briny mixture, meaning they've got some salt content in the water to lower

that freezing temperature. Um if you have fresh water that freezes at thirty two degrees fahrenheit or zero degrees celsius, seawater, which obviously is not the same thing as being used in hockey rink systems, uh seawater freezes at twenty eight point four degrees fahrenheit or minus two degrees celsius. So seawater has a salinity that's salt content of about three point five percent. That is not as salty as water

can get. Though. You can keep adding salt into water up to the point that the salt makes up about twenty three point three percent of the weight of the mixture. So at that point you reach what's called saturation. You cannot put more salt into that mixture. It will never dissolve. So at twenty three point you hit that maximum salinity. Now, at that concentration, saltwater would have a freezing temperature of minus twenty one point one degree celsius or minus five

point nine eight degrees fahrenheit, So very different. Right, You're talking about a vast array of temperatures there, and again it's all just based on the amount of salt in that water. So a lot of ice ranks, like I said, a lot of hockey ranks, use a briny mixture as the cooling mechanism for the base of the rank. And now the ice itself that's on the the rank, that's

pure ice. That's just water that doesn't have any salt content, and at all, the only thing that has the salt content is the system underneath the rink that is at a lower temperature in order to allow the ice to form the one that's actually being or one that's in use now on the rink. When we went up to talk, they were still putting this all together. Doesn't use a briny mixture. Instead, it uses glycol, which is a type of alcohol, and glycol also has a lower freezing point

than water. In fact, glycol will remain a liquid until you hit about negative seventy four degrees fahrenheit, which is about negative fifty nine degrees celsius. So if you can cool glycol down well below waters freezing temperature, but still above the freezing temperature of glycol itself, you're in business. You can keep pumping liquid glycol that's at a very low temperature at the very base of your ice rink, and that will provide the heat sink to pull heat

away from water and allow it to freeze. But this leads us to our second big problem to solve. How do you get the cooling liquid to that low temperature. How you keep your glycol or your briny mixture, and

they'll temperature lower than the freezing point for water. If the water you are adding is constantly transferring its heat to the system, how do you then get rid of that heat, because if you don't do that, you're cooling pipes will gradually warm up and then your ice rink will just become a very shallow swimming pool and people will not have very much fun. That is where the chillers come in. Chillers are all about transferring heat, so as you can siphon it away from one area and

dump it in another area. You cannot destroy energy, but you can move it from one place to another. So you can't destroy heat, but you can pull it from one location and disperse it into a different location. Chillers do this by taking advantage of thermal physics. And there's several different types of killers that use slightly different approaches, some of them dramatically different approaches, but they all have essentially the same end goal, which is to facilitate heat transfer.

We're gonna look at a general approach and talk about the types of chillers you're likely to run into if you were, I don't know, going to an ice rink or installing a massive HVAC system for an office building. So think of chillers as three loops that are adjacent to one another, but they don't connect to each other. So almost like three rubber bands that are very close together.

Within one loop, you have the chilled liquid. That is, this is the stuff that is creating the heat sync, that's pulling the heat away from whatever it is that you want to cool down. This might be an air conditioning system, or it might be again the basis the foundation for your ice rink. Uh. So you've got that, You've got the second loop that takes the heat gathered from the first loop. So that first loop starts to heat up as it's absorbing this heat. You've got to

find a way to remove that. You've got to find a way to dump that heat someplace. There's a second loop that it essentially does that. It takes the heat from the first loop and then finds a convenient spot to dump it. And then you have a third loop that is your refrigerant that kind of acts as the facilitator between loops one and two. In fact, it's the most important component of the entire system, is your refrigerant uh loop. Now there are four different pieces to the

chiller system. Within that refrigerant loop then make all of this possible. You have a compressor, you have a condenser, you have an expansion valve and you have an evaporator. And this leads us to another element of thermal physics, which is if you crank up pressure on a gas, for example, you not just increase the pressure of that substance,

you also increase its temperature. And it also means that you can push up the boiling point of a substance by putting it under pressure, which is also a great song with Freddie Mercury and David Bowie. So if you take a gas and you pressureize it enough, you can convert that gas into a liquid, even if the temperature of the substance is above its normal boiling point at

regular air pressure. So it will end up condensing into a liquid, whereas it would normally evaporate into a gas under that under a normal pressures, as long as you're cranking up the actual pressure of the gas. So here's how I think about it. On a molecular level, it's really easy to understand the behavior of solids, liquids and gases. A solid substance has its molecules pretty much locked into place. I mean, there's always some little movement, but it's more

or less locked into place. They hold their positions relative to each other that keeps a solid consistent. But a liquid has molecules that can move around more freely. They spread out a bit, they get to wander around, they test their boundaries because the liquid always is going to take the shape of whatever container it is in. Then a gas goes even further with molecules spreading out even more.

But if you do put that gas under pressure, you're effectively forcing those molecules closer together as if they were in a liquid. So if you do that enough, the gas condenses into a liquid. You push those molecules together enough to convert it into its liquid form. So how does a chiller take advantage of this? All? Right, this is gonna be a little tricky to describe without the use of visual aids, but I'm gonna do my best. So let's just imagine the system as simple as we

possibly can. Imagine a rectangle, and it's wider than it is tall. So you've got a wide rectangle. Now in the center part of the base of the rectangle, that bottom border of the rectangle, just imagine a circle right in the center of that. That circle is going to represent our compressor. Now at the top of the rectangle, opposite of our compressor will draw a little triangle, and that triangle is going to represent the expansion valve. So you can think of these as two gates. They keep

the pressure different on either side of the gates. On the right side of this rectangle, we're going to imagine that's the condenser, and on the left side, we're going to imagine that that is the evaporator. So refrigerant moves from the evaporator side through the condenser side via the compressor. So you have the refrigerant moving from evaporator into compressor where it gets compressed, thus the name, and then pushed

over to the condenser side. So we're going to take a journey with the refrigerant to understand how this works from a technical perspective. From the evaporator side, just as you get to the compressor, that refrigerant before it goes through the compressor is a low pressure arm gas. Typically, the compressor then compresses this gas so that the output on the other side, on the condenser side is a

high pressure hot gas. This hot gas then moves through the condenser and that's typically a long length of pipe or tubing that folds back and forth on itself. If you've ever looked into the back of a refrigerator or in an air conditioning unit, you've probably seen this where you've seen these these pipes that do these tight s curves over and over and over again. Well, that's the way it's laid out. In a condenser. The high temperature, high pressure gas moves through this length of pipe and

it can start to transfer some of that heat. Some of it gets transferred straight through the pipe, some of it typically gets transferred through fins that are uh connected to the pipes so that it can draw heat away through conductivity. It's it's conducting the heat and you then have um a fan typically that blows air across the system that uses convection to pull heat away as well. So this gas starts to lose some of that temperature. As it's moving through this series of s curves, it's

transferring heat to the air around it. Now, the higher pressure means that as this happens, the gas begins to condense into a liquid. As it makes its journey through this part of the loop, the liquid is still under a lot of pressure that you can't really pressurized liquid the way you can with gases, but it's still under a great deal push, you could think of it in that sense, um, but it's reaching more of a regular temperature. At the end of the condenser side, you have that

expansion valve which leads to the evaporator side. Now, the reason its valve is so that it can again create this partial seal. It's sealed. Whenever it's shut. You have a low pressure side on the other on the evaporate raator end of this loop the circuit, if you think of it that way. So you have high pressure on

the condenser side, low pressure on the evaporator side. That expansion valve allows for one way travel, so it goes from condenser to evaporator, and pressure, like temperature, is all about moving from areas of high concentration to low concentration. So the expansion valve allows this pressurized substance, this refrigerant, to pass through into that low pressure side, the evaporator side, and when it does, it suddenly finds itself with a lot more room to spread out than on the high

pressure side. Right Suddenly it doesn't have that high pressure to cram it together, and so the molecules of the refrigerant end up spreading out and as a result, the temperature begins to drop, so at the beginning of the refrigerant journey around the evaporator, it becomes a low pressure cold liquid, and as it moves through the evaporator, it starts to absorb heat from the system. Whatever it is

you're trying to cool. In this case, it would be the the stuff that's running underneath the rink, whether it's the brine or whether it's glycol, that would be tangential to this refrigerant system, and the refrigerant would be absorbing the heat from there, and as a result, the refrigerants starts to boil off, it starts to evaporate, thus the

name of operator. In air conditioning systems, this heat would be from the air of whatever area you were trying to cool, But in the case of the ice rink on the roof of our building, the heat is in that glycol that's running through the tubes that are under the rink itself. The refrigerant boils as it moves through this part of the loop and evaporates, and that turns into the low pressure warm gas that we started off with when I began talking about this refrigerant in the

first place. That low pressure warm gas that immediately moves through the compressor and becomes the high pressure, high temperature gas. So we're back at the beginning, and we just keep going through. It's a close system, so it doesn't go anywhere else. The refrigerant does not mix with any of the other loops. It just continuously goes through this process.

Now the glycol again access that separate loop, comes into close contact with a refrigerant, but it never actually shares a common line with it, so you never mix them together. The glycol will transfer heat over to the refrigerant, and because it's transferring heat, the glycoal itself becomes colder as a result, or if you prefer, the temperature decreases due to this heat transfer. The glycol then moves through its own pump to travel underneath the rink through lots of tubes.

I mean there were hundreds of these tubes underneath the rink, and it absorbs the heat from the environment as it moves through until it gets back to the heat exchanger part of the loop, and then again transfers heat to the refrigerant and goes all the way through it again. So again closed loop systems. It's just pumps moving liquid

through at this point. Typically you then would have a third loop, and this is the one that picks up all the heat that was pushed out from the condenser side of that refrigerant when it was that high pressure, high temperature gas. So there's some that are air cooled, but a lot of them end up being water cooled, so you have this water loop again on that side of it. You can use water in this particular system because you're not you're dealing with temperatures that are well

above the freezing point of water. You just have to make sure that the water is at a lower temperature than the gas going through the condenser, because again, heat's going to only move from high temperature to low temperature. So if the water you're using is high temperature and the condenser is at a high temperature, it's not very efficient. You need the water to be cool enough to actually pull heat away, or rather to accept heat that's being

rejected from the condenser. This water would then typically be pumped up to some sort of cooling mechanism like a cooling tower, and these are the big things you see on top of buildings that often emit enormous amounts of steam on cold days. If you've ever seen that. That's typically a cooling tower on the top of a building that's part of the HVAC system. The hot water will go into the cooling tower. It drips down over fins

that are inside the cooling tower. You typically have a fan or maybe a couple of fans at the top of the cooling tower that is drawing air into the tower. Their vents along the side that pull air in. The air moves over these fins that have the hot water on them, thus cooling the water, some of it evaporating away and then ejecting out the top of the cooling

tower being pushed out through that fan. So it's kind of like a vacuum cleaner, but instead of sucking up dirt, it's sucking up heat and air from the water, or heat from the water, but air in general, and blowing it up through the top. The cooling water ends up dripping down these fins, typically collects at a basin at the at the base of the cooling tower and then drains back down into the system. Uh and then back down to the heat exchange, your part of the chiller

that I was just talking about. So that's your basic parts of a chiller. And again it's the same principle that's working with things like refrigerators, it's working with air conditioners and also ice skating rinks. Now I've got a lot more to say about the technology behind ice skating rinks and maintaining them, but before I do any more of that, let's take a quick break to thank our sponsor.

All Right, So we've talked about how to get the temperature down low enough to freeze water and keep it at a temperature where you still have solid water a k. A. Ice. But how do you fill up the ice rink. The answer is that you do it very carefully, or if you prefer, meticulously and slowly. So a large permanent ice rink typically will have that concrete foundation, and underneath that you have a network of pipes that carry the cool

liquid that keep the concrete foundation nice and chili. The concrete will be at a temperature that is below the freezing point of water. Uh. You fill up the rink by spraying it with a fine mist of water onto the concrete layer to start off with the temperature of the concrete so low that those tiny water droplets pretty much freeze as they make contact with the concrete, it doesn't take along at all for it to freeze to

the surface. The first couple of layers of ice are always extremely thin, So for a typical hockey rink that uses this concrete approach, you're talking about an inch thick, which is about point eight five millimeters, and once those layers are down, you paint it. So most ice rinks will lay down a layer of paint on those first couple of layers of ice. This helps do a few things.

For one, it hides the base of the ice rink away, so you're not looking at clear ice and seeing a concrete floor, or in the case of the ice rink that's on the roof of our building, you wouldn't see a series of tubes that are pink because call has a the glyde call they're using has a pink tent to it, so you would otherwise see just lines and lines and lines of pink tubes. So they paint the ice that it obscures that. It also will allow for good contrast with any logos or words that you want

to paint on the ice rink. So, for example, with hockey rinks, you would typically paint the name of the hockey team on there, maybe put their logo on, maybe a sponsor logo could go on there. But you want there to be good contrast, so that's why you have that white base. Also, it creates great contrast for the puck in hockey because you want to be able to see that if you're a player or or an observer. Really, So after that layer of paint would come another layer

of ice. This one is a little more thick. It is one of an inch thick, that's about one point six millimeters, and that acts like a seiler for that layer of paint that was just laid down, and then you could put more paint down on top of this layer. So this is where you would paint logos or the lines and circles and arcane symbols that make up the rules of hockey that I never got a chance to understand because Atlanta's team was taken from us before I

could ever get a full grasp on the rules. And yeah, I know, I said I wouldn't talk about it, but I'm still angry about it. Anyway, after that you would add your final layer of ice on top. But this actually would happen in several stages, so it's one solid layer, but it's done in phases. This is the actual surface

that people would skate upon. Now. Typical hockey rank, which again is much larger than the one that we have upstairs, would require between twelve thousand and fifteen thousand gallons of water, that's forty thousand to fifty seven thousand liters. Most of that water gets added in that final layer. The overwhelming majority of the water is added in that last layer. And whereas the early layers get added as a fine missed,

the final one is a bit less delicate. They typically will just use a flooding hose to pour water out on top of the rink, and we're talking about ten thousand gallons of water at a rate of about five hundred to six hundred gallons per hour, which means it can take about twenty hours or so to add that

final layer to the rink. And according to Don McMillan, whom hell Stuff Works, interviewed for an article on how ice rinks work, most rinks will allow each five hundred or six hundred gallon amount in that hour to freeze completely before they start adding more water. So again in phases, and that helps maintain a really good quality of ice and ice quality is really a thing. You can have good ice and you can't have bad ice. If your

temperature isn't right, you're gonna have some issues. So for example, um, outside, if you don't have the right temperature, it's gonna start melting. You'll have some slushy ice at the top, and that's not great for skating. Um if you have really high humidity, you're gonna end up with a lot of fog over the ice, which happens here because we have a lot

of humidity in Atlanta. And uh, it's pretty spooky looking in the morning to walk up to Pont City Market and see the the the mist pouring off the top of the building. Professional ice skaters tend to like their ice at a relatively warm to twenty degrees fahrenheit at the surface. That's minus three point three three to minus

two point to two degrees celsius. Hockey players like it a little colder because the ice is harder, it's more resilient, doesn't grip the ice skates quite like the softer, less cold ice does. They prefer the surface to be closer to twenty four to twenty six degrees fahrenheit or minus four point four four to minus three point three three

degrees celsius. Now, I had a chance to chat with the project manager for the ice rink installed on the roof of our building, and we cover some of the stuff I just mentioned, but I think it's a pretty interesting discussion, including all the work that was required to install an ice rink on the roof of a nine story building in Atlanta, Georgia, and just the amount of sheer effort it required to do that. So here's what

he had to say. Oh and just so you guys know, we were talking up on the roof on a windy days, so it was also during while you know, construction, they were still playing the ice ring together, so the audio quality is a bit atmospheric. But here he goes, so basically, you got to have a level surface. Obviously, if you're gonna make guys it's greight water, you can have it running downhill. So we were fortunate enough to already have

a basically a perfectly leveled deck up here. So then we put in foam insulation over that deck, uh, and then a biscuen plastic and then we put these mats together, and each of these tubes is a circulating system that will run the glacoll pump pressurized probably minus ten twenty degree claike all through and as the glacoll is running through it and freezing, you basically take your standard garden

host and start missing water. And as soon as the water hits that minus twenty degree glycol to being, it starts to freeze. And so you start building that that base of ice. And they'll basically take it from from below the glacoll t being that you see here to about a half inch above it, and then they'll paint it white so that you don't see everything all this pink glacol underneath. So then they'll put after they've got that basecoat of white paint on it, then they'll put

another layer of clear ice on it. So it looks just like any other ice skating rink in America, hockey rink that you would see on TV. And if we wanted to, you could paint lines, or we could have a sponsor, we would have a how how stuff works out there, and you know, logo in the middle and everybody skating would be skating over it, and that's pretty much that. That's you know, that's the the end of

the process, and it's pretty simple. It's what happens prior to that where all the engineering comes into play and uh, all the hard work happens. So in order for us to create this on the roof, a lot had to happen. We had a hundred and twenty ton chiller that we had to crane to the roof, and so that was we had a three hundred foot crane basically that we hooked that up to. But before we did that, you just can't set pounds plus another three thousand pounds of

glycol on a roof. It has to be engineered. So we did structural engineering analysis and then built a platform that would handle the weight the distribution, because not only is it weight, you also need a little shock absorbers in there to handle any of the vibrations because once you tie into the columns and the beams, you don't want the neighbors below hearing or feeling any any vibration

and rattling. So we isolated that system, craned up the chiller, and uh and at that point we're running six inch steel pipe from the chiller up to the rink here and it's a closed system. So it's just a massive circulation of glycol. Because we had to locate our chiller UM further than about twenty feet from the rank. We

had to put a massive pump on it too. So the chillers themselves have a limited pressure capability for runs, but our run was so long, we we put a huge pump on it so that we get the constant pressure that we need and UM and that we maintain our ability to keep this thing frozen. We're lucky that we're under a tent. If we were outside in Atlanta, you know, we we don't have a lot of days of constantly below freezing here and in the sunshine it would probably melt the ice at some of the some

of the other outdoor rinks struggle with that. UM, we will not have any issues. I'm told by the experts. Without rect sunlight on our rank that we should have a great surface. We could probably do it all year round, believe it or not. UM. I know that this company UH does things worldwide and they have outdoor outdoor skating in San Diego, so and they say to run that in the summertime there. So you just have to have a you know, it's all about your how big your

chiller is, and how big your rank is. In order to to make that happen, and then all the six inch piping of course had to be highly insulated. Uh. You don't want to lose any of your value, your temperature values. You know, steel obviously would would bleed out and into the ambient air temperature. So we've got about

the two inches of insulation around all the piping. Uh. From an electrical standpoint where four naty volts three phase uh, so lots of lots of juice to run all this, as you're probably aware, you know, the bigger equipment, anything that involves heating and cool really it's gonna pull a lot of amps and it's gonna need a lot of a lot of voltage. So we we actually ran additional power up here on the roof in order to make

that happen. Can't just plug it into the outlet on the wall, regrettably, because running power from the west side of the building to over here is it's it's pricey at at the thirty bucks a foot just for the just for the wire, just for the cable. So they the power was was a disappointment. My landlord has been very helpful with with helping us out on some of that. So basically what we're looking at here for for people who may not be aware of how this all works,

we're looking at essentially a heat exchanger. You've got your glycol, which has a lower freezing point than water, so you can lower that temperature of the glycol much lower than the freezing point of water. You run that through the system, water hits it. Obviously, the heat transfers into the glycoal system, which is so cold and so massive and being up so quickly that it's not effectively raising the temperature of

glycol enough for it to affect uh. But it's not like you're going to have one part of the rink that's slushy, whereas the rest of it's all all nice and solid. It goes, pumps through the system, hits the chiller, reduces the temperature of the glycol back down to what you wanted at the top, goes right back in because it's a closed loop, and just continuously pumps through to keep that water at that that below freezing temperature, so that you have anice solid rink. Is that more or

less what we're looking at. That's exactly what we're looking at here, And and In fact, the chiller has got it the sensors on it, and it will monitor the pressure and it will also monitor the temperature. So it's kind of a smart system in order to be efficient to tell itself exactly what it needs to do to maintain the conditions that we're looking that you just described

out here. Well, that's great because this is exactly the same sort of principle that you would see on things like air conditioners or a refrigerator, just on a much more are massive scale. And it temperature is far lower than what you would I mean, I like a nice cool man cave, but minus twenties is low even for me. Yeah, you know, it's not something you want to walk around barefoot on in the garage or in your cave. So that's great. About how long would it take to go

from from dry to full rank? Uh? Knowing that this is going through phases right once, once we're at this point where the system is set up, the grid is laid down, and once we flip that compressor on within an hour, we're gonna start making ice. As soon as we reach the right tempts that are circulating through the system, we're gonna start spraying down that that first coat of water in order to uh to build up that ice. So it should happen very quickly. Uh, you know, we

probably will. It'll take hours, of course to build up inches. Will probably get to about three inches of ice out here. That may take some time. But again, because we're not interact sunlight, we're and it is cool at night. So if we start this in the afternoon and work into the evening, we should have a solid rink within a matter of four or five hours up here to skate on. That's incredibly one of the do you happen to know

the dimensions of this rank? Yes, this rank is fifty by seventy, so we're right at suare feet here, So just five hours or less for that much that much square footage is really impressive when you sit there and you think about the energy requirements, as you were saying, just for the equipment is incredible, but if we're talking about just physics, the energy requirements to remove that much heat so that you can convert water into ice for that much square footage, it's it's phenomenal and it's an

elegant solution to I'm sad that my listeners won't be able to see this. Well, we'll share some images on social as well to kind of get a look at how this works. But when you see it and you see the solution that was proposed, from an engineering perspective, it is simple and elegant and yet incredibly effective to be able to turn that much water into that much

ice that quickly. Um Again, when you start looking at it from a physics perspective, like that's a that's a lot of energy that you have to take into consideration. And of course that's before anyone that tries to manage a triple axel out here. I will not be one

of those people. I might try my hand at skating, but considering my lack of grace just on roller skates, I suspect spectacular white belts would be to followed so well when they when that ice has finished and ready to skate on, you're gonna hear me tap out at the other sides and turn it over to another group

of people to handle it from there on out. You know, to your point, the amount of energy and and everything that goes into this, you know the I think only mother nature really does it better than what we're doing here, and it is it is when you start to think about the the energy and the physics involved, it is h s daunting really sure. Yeah, yeah, And as you we were pointing out, just the just taking into consideration and how they handle the weight is an enormous undertaking

because you're on we're on the rooftop of an existing structure. Obviously, Uh one, the rooftop was not necessarily intended to hold a ton chiller plus a rinkfull of solid water, uh not dimensional people on top of it. But that's incidental compared to everything else. Uh So yeah, having to take that into consideration and look at and how is the building built, how does that weight distribute already? Love would you need to do in order to offset that in

any way? If there's a point where you think, well, we'd love to play it here, but the roof literally can't support it there, There's a lot of things you've taken into account, and I imagined the whole process took quite some time before anything was laid down at all. We we should really started visioning this over a year ago and started to kind of analyze the hurdles that we would have in front of us, and uh, structural engineering. Of course, it was our first consideration, can we handle

the pounds per square foot up here? What's the rating of this ice gonna be? And how well is our deck engineered? And and so we had to bring in, you know, the brainy acts to help us out and figure out exactly what we could handle up here, because it's not just ice. We have wind load up here, and then we're gonna have a human load as well. So if you really start to factor in all of that, and the math kicks in. And we were fortunate that we have very robust engineering up here and that we

were able to to pull this off. But uh yeah, almost at every turn of the project we were we were surprised by the complexity of it and surprised because this was a little bit out of our wheelhouse. This was a new venture for us, and so the learning curve was steep. Well. To me, those are the most exciting projects to work on. I've always said that my job is one of the best I can imagine because I get to learn new things every single week, and that you know, that challenge is what I feed off of.

At times, it can obviously become so challenging as to be frustrating, but the fact that we're looking at a project that's so close to being ready for the public to see. I'm very excited to actually get a look at the rink once it's all finished. Being able to see that in this state is actually really cool for me because it's something that I typically would never have been able to see, you know, outside of just images or maybe some videos. So having this opportunity is fantastic.

I really appreciate it, and I can't wait to see this chiller I've heard so much about. Well it was. It was a beast and and to see it come off of a huge flatbed truck and have the crane and of course you just don't latch onto it. You can imagine, you know, even a five mile an hour breeze as you're craning something hundreds of feet into the air can get a little bit dicey. So they just just watching the crane set up, it's booms and it's

it's weight distribution. That was a whole another engineering lesson in itself. Again, the physics involved in every phase of this was really amazing, and and yeah it was. It was an enormous amount of fund for me to be a part of this, To go through the learning curve and I can now speak in in some languages of physics that I couldn't have before we started the project. You never know, and that's gonna come in handy on the future projects. And that's also well, thank you so

much for showing the rink. I really appreciate it. I'm I really can't wait to see this one. It's ways ago well as a pleasure having you up here. And uh, I think we'll force you to get into a pair of skates and get on the ice when we're done. I think I have to. At this point, I want to thank Mr Brett hole Ride for inviting us up and taking a look at the ice rink in progress.

It was pretty awesome, not just to see the rink itself and how it was laid out and with all those tubes of glycol underneath, but also just that massive chiller, hundred twenty ton chiller on the roof of this building. It was enormous, along with the huge pump that was necessary to actually move the glycol through the system, and we never would have had a chance without it. So thank you again, Brett. And I got a little bit

more to say about maintaining an ice rink. But before I go into that last section, let's take another quick break to thank our sponsor. Alright, I thought it might be fun to end this episode with a look at ice resurfaceers. Typically, folks would refer to these as a Zamboni, But just to be clear, Zamboni refers to a particular brand of ice resurfacing machines. It's just that most folks use that brand name to refer to the technology in general, much the same way that some people will refer to

any copy machine as a xerox. Now, the purpose of these machines is to repair and polish the surface of ice rinks as they experience wear and tear, and it does not take very long for metal ice skates to carve up that nice, pristine surface of an ice rink. And once in a while you need to fix things so that they're more attractive and to avoid situations where a skater goes topsy turvy after hitting a particularly big

divot cut out of the surface. Now, in the good old days, and by that I mean the awful old days, this was all done by hand. People would actually venture out onto the skating surface with tools to physically chip away at that top layer in order to get as

smooth as surface as possible. They would use shovels to shovel up any of the ice shavings that they created, either from skating or just scraping that top layer of ice, and they would use water hoses to pour out more water to replace the ice lost from the whole process as well, and they'd use squeegees and towels to help spread the water in a thin layer across the entire surface to get that nice shiny appearance and make everything clean and beautiful again. And the whole process would take

several hours of backbreaking work. Then in you have a visionary named Frank Zamboni who decided to tackle this problem and find a better way to resurface an ice rink. He and his brother Lawrence had opened up an ice rink in California, Southern California at that and they had been using a tractor that was outfitted with a large blade to scrape that top layer before manually shoveling up all the ice shavings and pouring hot water from a hose onto the rink and then squeegeeing it by hand

across the surface. The whole process, even with the tractor, meant that it would take about an hour and a half to resurface their ice rink, which was not an enormous rink. It was a It was a decent size one is bigger than the one that we have upstairs, but not the biggest one in the world. And so Zamboni thought, there's gotta be a better way to do this. His solution was to create a new type of vehicle that could do as much of this work as pile

all by itself. And he worked on this concept for nearly a decade and created a truly terrifying Frankenstein's Monster of a vehicle out of parts that included stuff like there was a cylinder from a plane, there was a jeep engine driving the whole thing. There was an oil derec chassis. So this invention first debuted in nineteen forty nine, it obviously went through lots of different evolutionary processes until it was refined into the sleek, sexy vehicle we all

know and love today. And of course, there's more than justice Amboni ice resurfacing machines out there at this time. There's all sorts of ones that are out there. But here's what a modern ice resurfacing vehicle actually does. So underneath the vehicle there's a blade that is positioned inside

an overall structure that's called the conditioner. This you can actually raise and lower underneath the zamboni, so when you're just driving it onto the surface of the ice, you can raise it up so nothing is dragging, and when you're ready to start, you lower the conditioner down and then you typically have a control that can put the angle of attack for the blade at such so that you can cut exactly the amount of ice you want

off the top surface. For hockey rinks, it's a very very thin layer, but other rinks it might be a little bit more more severe, depending upon what they're trying to do. So the blade is typically somewhere between seventy seven to ninety six inches in width, which is about a hundreds and it cuts that top layer of the ice, the very top layer, removes any protrusions, helps level out

any big divots. Uh. There are a pair of augers that catch all the shavings, the the ice chips or the snow and they move it into a snow tank. Augers are are essentially large screws, so you rotational force to move those shavings around. There's one that's horizontal and it ends up pulling all the ice shavings, are really pushing all the ice shavings into the center back portion

of the zamboni. Then there's a vertical auger that lifts from that central packed mass and moves it up to the snow tank, this waist tank that's typically on the front of the zamboni or ice resurfacer, i should say. And then typically one of these machines will pour hot water onto the ice. Behind this there's maybe it's warm, not hot water, and helps level out anything that the

blade wasn't able to get. There's a squeegee that is right behind this hot water that then allows that to get sucked back up into the system so that it can be recycled. And then there's another hot water emitter at the very back of the zamboni just before you get to the the extreme rear of the vehicle where

there's a flap. It's essentially a towel at the very back, and so hot water drips out and the towel then spreads the hot water against the surface of the ice ice free surfacers use hot water instead of cold water because the hot water, when it makes contact with the ice rink, will start to melt that surface ice just slightly before it begins to free freeze into a solid layer.

If you were to use cold water, cold water freezes so quickly that you end up more like very thin additional layers on top, and those chip way very easily. So if you're doing some sort of fancy ice skating or you're doing you know, playing hockey or something, you end up getting these big chips that fly up, and that typically is not really preferred. So that's why they use hot water. It it melts the top surface of the ice just a little bit before it all refreezes

and makes it more of a solid layer of ice. Often, Um, you'll have a couple of other elements, like there might be another brush. It depends upon the vehicle. Some of them run on natural gas, some of them run on battery power. Um, if you're looking at a full size zamboni with a full tank, these things are heavy. They weigh about eleven thousand pounds or four thousand ns. These are massive, heavy vehicles. So running across that ice is

no joke. And they also tend to have a metal studs on their tires to give them enough purchase to be able to actually move across the ice effectively. And according to Car and Driver, operating a zamboni isn't exactly like driving a sports car. The report said, quote, visibility from the elevated left rear position is poor, the abrupt throttle tip in takes some getting used to, and the vague steering is totally seventies Cadillac end quote. But it's still kind of like to ride on one, though, And

that's our show about ice rinks. I'm still not likely to get on one anytime soon unless I just decide that a few nice weeks in traction would be a really good vacation. But like many Southerners, I really only trust ice if it's in my t That wraps up

this episode. If you guys have any suggestions for future episodes of Tech Stuff, whether it's a particular technology company that's been important in tech, or a figure that's really important in tech, or maybe there's someone you would love me to interview or have on as a guest host. Any of those suggestions, I welcome them all. You can write me the email address for the show is tech Stuff at how stuff works dot com, or you can

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