This episode of the HVAC school podcast is made possible by our happy fantastic, incredible sponsors carrier, Mitsubishi, Electric cooling and heating, the uei hub, smart kit, both their air probes, temperature and humidity, and their pressure and line temperature probes to find out more about this kit. By going to Yui, I test comm refrigeration technologies at refridge tech, comm makers of wet rag, viper products, night log and the new pan and drain spray, which burt was just telling me about mmm-hmm care to comment on that yeah. I've really liked it so far. It smells fantastic, I like it, because I can spray it exactly where I want it from like two feet away.

You would try to stand like really far back in his spot. No, you get all sorts of opportunities when you were doing AC work. To do that, I wouldn't know anything about that when I sharpen your aim: yeah yeah and then also air laces, the bipolar and nano whole home purification products which bird also has in his house care to comment about that they're, fantastic you're, saying fantastic too much. Oh! That's my word: no I've been very happy notice, the media difference and the way in my house smelled.

Originally we had a pretty bad after we moved in mold outbreak in our house behind our scene. We have a leak, so we had to have that taken care of and at the time our twins just came home from the hospital they're brand new babies and they got exposed to some stuff and allergies for him. -- it things like that and so anyways long story short still dealing with some of the overlap from that and the kids were pretty much every night right about midnight. Waking up coughing and my son Isaiah always having respiratory issues.

So we went ahead and put those in our home to help clean up our air and see how that would work and less than a week they stopped coughing. In the night they haven't woke up. Coughing sit. It sounds like you're making a false claim here, bird.

It doesn't get it call the FCC on you, you can call whoever you like, okay, and maybe they were just having a wake up in the middle of night coughing for three months in a row and it's gone now. That's fine, but the reality is. I've noticed a difference and I feel like it's made a difference for them, I'm happy about that. We did the Petrie test before and after about 70 percent improvement, a lot of people have seen that test out there, some pretty ugly pictures from the original results.

When we did the tests in my house, I'm definitely happy about that. I'm glad it's working out for you yeah now I have a story to tell yeah just needs to get shorter. Yes, all right, you find out more about all of the air oasis products by going to Errol ASIS calm. I also want to thank retro tech, retro tech makers of really good quality precision.

Manometer we use it. It's covered iam 32. We actually have two of them that can then be used with a blower door or with a duct leakage jester or if you're doing, zonal pressure testing any really advanced pressure testing. In a space where you're measuring down into the Pascal range, we highly recommend the retro tech products and specifically the DM 32.

And finally, when I mentioned right, soft writes often writes Ofcom, really good software for doing manual, J manual D. I was at the humid climate conference the other day in Austin and Corbett Lunsford cornered me as he often does and asked me what product we use for loads and for duct design, and I recommended write soft he went home, got, write soft and he just texted Me yesterday and said, he's really been enjoying it and he wonders why he hadn't done it sooner. So you can find out more about write soft by going to write soft calm, that's W righ, t soft calm, and now the man who stays humble because he has two teenage sons who always let him know how much smarter they are than him, Brian or first Of all you know what is this podcast for you know, I, don't you don't know not this episode with the podcast in general, it's the podcast that you know one teaches you some things you might not have already known reminds you some things. It's for text by text and it broadens your knowledge in the heating, ventilation and air conditioning field.

Okay, I don't know the line the line is it helps you remember some things you might have forgotten about the HVAC trade as well as helps you remember some things. You might have forgotten to know in the first place. I remember that no different versions of it yeah well, I basically said the same thing: yeah I'm trying to be cute based on I mean that's it's it kind of a key thing anyway, I'm Brian and with us. Today we have Bert.

What's up yeah Bert, some of you know Bert Bert's, a little bit of a cult figure yeah and the HVAC school group, especially that's why I have two names online. What are those I don't know whenever I'm on Facebook? My name is Jessie, so it is yeah, and so people were probably like who's this guy right and then we have Kieran with us good morning, you'll notice that Kieran sounds a little different. It's because he's from Montana is that strong Montana accent yeah yeah. He says some weird words like when we were working together and noticed.

He said he's about a lie: britches trouser trousers over the body browsers yeah and I was like used to keep going pants nailed. It so we're working on that and he also said rubbish picking up stuff in the bottom of my van and said better grab all this rubbish. Sorry trash right. Yes, yes, yes, sir, Karen is not from Montana, as they say in the Andy.

Griffith Show he's from the old country from Great Britain from Great Britain. We just call it Britain, as we aren't sure how great today we're gon na talk about the basic refrigerant circuit, and we did a episode about the basic refrigerant circuit. At the beginning of HVAC, school and Bert, told me the other day. He said we need to get back to the basics again and then I said why could republish and you're like? No, you need to rerecord it yeah, because it's kind of jacked up, I guess, was your feeling about it.

That was my feeling about it. Only I never told you that right, so I'm not sure who you were talking to okay, so Bert and Kieran's role here are to heckle me. Mostly that's the primary job, so Bert's job is head. Heckler Kieran's role is head question-asker, okay, okay, so you have to ask questions even if they're completely irrelevant just random questions about the refrigeration or you could ask me questions like do.

I think that the movie watership down isn't appropriate for children, for example, and the answer is no, it has lots of rabbit violence, but it's very important for children. This is gon na, be a terrible pun. Yes, okay. This is great basic, refrigerant circuit, so the four basic components.

So, let's go through the components in lines, because that is the first thing that my instructor made me do when I went to AC school and winter garden. Florida ron carey was his name made me, stand at the whiteboard and write over and over the four basic components and the four basic lines and there's one controversial one out of this eight. And so, let's see if you can pick up which it is through. The metering device, immediate advice is not controversial.

No, no. The metering device stays away from conversations about politics and religion and Thanksgiving it's very unconscious North even know the receiver is not one of the four it's not. The compressor is not the evaporator, nothing condensing. No but again, there's four components and there's four lines: okay, so compressor condenser metering, device evaporator, those are the four components and then the four lines are huge: okay, head controversy: there, no, no there's no head because discharge line when we say head pressure.

Oh sorry, I mean discharge suction run. Is it run? Do we call it run for something I saw something in a book the other day. I think this is the great British coming in and interfering live good line, yeah, okay, so again three faiths. Okay, let's see this is the controversial one all right, so we've got, let's do an order between the compressor and the condenser is the what line BIRT discharge discharge, the line between the condenser and the metering device is the liquid line is the liquid line.

He said you knew that one between the metering device in the evaporator to fail okay, so he calls it the two-phase line. Some people call it. Sometimes there is no line right. In fact, in a lot of most cases in residential there's no line at all, we don't see a line.

I call it the expansion line. Some people will call it the flash gas line. There's another name that people call it. I call it capillary tubes.

No! Well! That's not a capillary tube, okay quickly. There's a lot of controversy on this, and I'm just gon na make my own stand here. No quickly, a capillary tube is a type of metering device that is just a small tube and the amount of restriction. The conductance rate, through that capillary tube, is based on the diameter, the internal diameter of the capillary tube and what other factor the pressure of the refrigerant well speed of the flow.

No, that affects it, but as far as how much that capillary tube restricts is based on the internal diameter Plus how many times, what no because a true capillary tube, is only one tube. Okay, it's the length of the leg them to do so. The longer the length, the more it restricts and the diameter so you'll see cap tubes, primarily in small refrigeration. I mean that's old refrigerators.

That sort of thing - that's where you don't even even a lot of modern refrigerators - are gon na have cap tubes in them. A capillary tube is not the same as a distributor tube, and this is something that technicians get confused, they'll call it a capillary tube and basically in the field, they say that to mean any small tube right. I go. That's a capillary tube.

Well, no, a capillary tube is a specific type of metering device like technically speaking, mm anyway. All right so you've have the compressor, condenser metering device, evaporator the line between the metering device and the evaporator. I call the expansion line, but it really doesn't matter what you call it so long. As you know what it is where's a case in the type of work we do where you will actually see an expansion line.

I see it on mini splits, mini splits. Yes, also known as necklace, yes, alright, so, as you know, I've worked with true tech tools. Tr? U tech tools comm, since the very beginning, Bill's phone is one of the first people who I talked to after I started the HVAC School podcast about sponsoring and turning this into something that was a little bigger and we never ended up doing a true sponsorship. But what we found is is that Bill and I just help each other.

We work together, no money changes hands, but we just find ways to help one another as we both serve the industry build us a lot of really great things for the industry. A lot of you may not know this, but Jim Bergman, who is one of the common guests who come on he's the founder of measure, quick, the measure quick app as well as the owner, and I guess, chief development officer or whatever product development for redfish Instruments. Super smart guy - and he actually founded, was one of the founders of true tech tools as well. So when you see throughout the excellence that goes into true tech tools, technically that has a lot to do with both bill spoon.

The current president and Jim Bergman, who later on left your tech tools to start some other adventures, there's a really good company, and one thing you may not know, is that you can get a lot of the products that I talk about here on the podcast, the Testo products - you have talked a lot about test, Oh, is the test of 6:05 eyes. You can get the uei hub, smart kits, the hygrometers, the hub and the hub for the hub is the thermal hygrometers, the induct humidity and temperature sensors that I, like so much with the really thin probes. You can also get their pressure and temperature probes by going to true tech tools, calm and use the offer code gets cooled. You get a great discount another product that you may not know that you can get from true tech tools.

Is the refrigeration technologies products so their Viper cleaners, my log most of the products from refrigeration technologies? You can get at true check tools if your local provider doesn't happen to have it and then also you can get the retro tech, blower doors and duct leakage testers that I talked about quite often from true tech tools as well, so a lot of different products. I would suggest that you take a look at true tech tools. If you haven't been there recently and see the great discounts you can get by using our offer code get schooled all right here we go back to the basic refrigerant circuit, all right, so you have the compressor, condenser metering device evaporator over between the metering device. In the evaporator now and then between the evaporator and the compressor, what is that line called suction? That's called the suction line right, so these are all fairly obvious names.

So, let's go through. Why they're obvious names, alright suction line? Why do we call it the suction line? Because the compressor sucks, because you can wrestlers drawing the refrigerant back on the low-pressure side, the discharge line? Why do we call the discharge line? Because the compressor discharges to the condenser, the liquid line? Why do we call it? The liquid line, because the condenser condenses the vapor refrigerant into a high-pressure liquid correct. And why do we call it the expansion line? Because the metering device in a solid spits it out as a two-phase mix with liquid and vapor to the evaporator right? Because it has a pressure drop when you give it that pressure drop, which is the job of the metering device, then it expands on the other side and it's begins to expand into a vapor. So it starts to make that change and in fact what it's doing is boiling alright.

So now let's go through and talk about each component and what each component actually does. Okay, what the job of each component is bird, I feel like I'm losing you buddy. Well, it's okay! I'm here! Oh yeah! Okay! Here, that's good! So you have the compressor. Why is it a compressor and not a pump because it compresses the refrigerant it does? It makes a higher pressure.

Yeah I mean it takes in the low pressure vapor refrigerant from the evaporator and discharges it as a high pressure, the vapor refrigerant to the condenser. So a pump could move liquid, but a compressor is not gon na move liquid. Why? Not? Because it actually is literally compressing the refrigerant and a liquid does not compress so a lot of people will say a liquid is non compressible and which is not true. Everything is compressible, oh come, but it requires so much force right to compress a liquid.

I mean, if you see, hydraulics and a bulldozer, for example, you're using a compressed liquid to drive these crazy crazy amounts of force and you're using it, because a liquid doesn't compress at least not in any significant way. So we can't run liquid through a compressor. That's one of the absolute rules of a compressor: you don't run liquid through it, but the reason it's a compressor. The reason why is compresses is because it's taking a vapor and it's taking it from a larger Uman, it's forcing it into a smaller volume.

That's what you're doing a pump can't do that with the liquid. So if you have a water pump, for example, and you look at how a water pump is designed like a little circulating, pump a little taco pump or whatever I don't know if it's taco or takeout whatever I know a lot of my hydronic guys are like This guy's friggin idiot, he doesn't even know that let's go to groom to Foss a groom, Faust pump, you open it up and there's this little impeller I mean it's like a little fan and it just spins and moves the water along. It's not compressing the water. So it's a different design.

There is a difference between a compressor and a pump and a lot of the metaphors we use when we talk about the refrigerant circuit or even when we talk about electrical theory and a lot of cases, we pretend like it is a pump. We use a lot of analogies with water but of course water and it's where we normally interact with it, is a liquid, and so it's not the same. You take this low temperature, low pressure, vapor right, you run it into the compressor, and what does it do once it gets inside that compressor, Burt I'll? Let you take this one. What happens to it gets compressed by the compressor? What does it do? First, before it gets compressed by the compressor, it cools the compressor as it passes through that's important for the compressor before getting compressed.

If you imagine so imagine a residential like commercial system, yeah typical systems that you work on, okay, every day, yeah every day, yeah because every day, you're hustling right. Absolutely absolutely that's true about you, especially so you work on these compressors and you imagine that refrigerant going into that suction line on that compressor, think of a scroll, compressor! Okay, you see it dumps down into that suction line and dumps down in what is it doing? It's definitely moving and possibly picking up some oil if it's going through an accumulator, but also picking up some heat from the compressor. What does the accumulator have to do with it? Why'd you bring that up, I'm just trying to figure out what you're aiming at I'm just saying it like. If you imagine this, because here's how I use I'm imagining it, but I don't see a lot happening before it gets compressed.

Okay, all right! That's good! It's good that that's how you feel about it, or so I used to imagine that the refrigerant went into that compressor like that little pipe there right, I'm going into the compressor in that pipe then fed right into the head of that compressor and it just pumped It right out yeah, that's not what happens. Probably what that is what I picture. I'm a head right. That's not what happened! No, what happens you just pretty much fill the inside of that compressor with vapor right just loaded that whole chamber right that whole inside shell is like a big refrigerant container.

That's pretty cool, okay and packed inside that refrigerant container is what two things primarily oil. Well, you really can't let go of that. I know okay, what is in there oil? Okay, what else vapor refrigerant right? What else oil oil again ease inside that compression right? Well, there's some windings right now! Can it? What do you call the windings? What is that called winding? What does it call copper? What is it called a thing that has windings in it that make thing go spinny. What's that called a motor, a motor, I used to call it an engine.

It's not. I literally called it an engine for like my first job. No don't do that, so it's a motor right, yeah and then what else is in there gasoline. Okay, no way only is Joe gasoline get done to get focus here.

Pistons, you see you had one. I scroll compressor, you don't have school, but you would just call the actual compressor portion the head of the compressor. The part that actually does the compressing right, yeah, okay, makes sense. Let me follow me absolutely all right good.

Do you have oil? You have vapor, you have the motor that drives again. I keep wanting to say pump. I mean that's, naturally how we want to think about it, but it's not actually pump. That's actually the compressor portion, the mechanical portion that compresses the refrigerant all right.

So your fridge down that section, let dump sound inside that compressor and inside that compressor. There is oil, and there is also this hot motor. A motor produces heat, it's sealed in there, so that refrigerant is going to pick up a lot of that heat from that motor. So it's gon na cool the motor.

It's also gon na cool the internal components of the compressor itself, because you have friction you know. I think spinning around in there and you get to get all that heat out of there right mm-hmm. So that's one of the jobs of the refrigerant is refrigerant has to be low enough temperature. It has to have enough refrigerant density that it can cool that compressor.

Hopefully, below 61 degrees, no, not below 61 degrees, hopefully below 61 degrees over the refrigerant via a low 61 degrees. Entering that compressor, okay or Copeland will find you, I think it's 65. I respect that. Okay, yeah, so ya, Koplin recommends - and I correct me if I'm wrong here, but I believe it's 65 degrees.

They want the refrigerant to be less than that on a typical high temp air conditioning application in order to properly cool that refrigerant. But it also even more importantly than the temperature of the refrigerant is the density of the refrigerant. And how can you tell the density of the refrigerant coming into the compressor, the PSI? The PSI also known as the pressure square in pounds per square - and I don't square yes coming in so the higher the pressure, the more the refrigerant density, it's kind of cool how that works, it's pretty simple, so the temperature of it and the density of it Dictate how well it's going to cool that compressor? That's it pretty simple! We also have to care about the oil, and so, if we bring liquid into that compressor, it goes down that suction line dumps down in there mixes with that oil and there's liquid in it. What's going to happen to that oil, well, that oil is going to tend to start to foam you're going to dilute that oil with liquid refrigerant and that's going to create lubrication problems.

Oil is not going to do what it's supposed to do. If you bring liquid refrigerant into that compressor, right, yeah Wow, not good! So in my head, I always pictured, like you said that tube feeding straight into that compression and when there was liquid in it it was just being smashed right into the compressor right into that. Right, but there is a chance for it to boil off there. It's a extremely likely chance, like the odds that you're going to fill plug a compressor with it running right are super slim super slim when we talk about slugging, a compressor, that's more for air-cooled compressors.

When you're running the equipment, it can happen, so I'm not saying it's impossible, but it's very unlikely that you're going to slug a compressor right all right what we do when we bring liquid into a compressor into the crankcase itself. We flood the compressor flooding. The compressor means that you're just bringing liquid into the crankcase and it's mixing with that oil and it's foaming and it's you end up losing the oil and the compressor doesn't get it washes out. The bearing surfaces washes the oil off because it's a solvent.

So when you have that boiling refrigerant, imagine it's like taking one of those electronics, cleaners and spraying it on something because it actually boils off. Then it removes the oil off of whatever you're cleaning or whatever it's exactly the same thing that's happening when you're bringing that in because you don't just have the compression chamber, you have all the bearings and everything that's leading up to it. Cuz, you imagine, you have this motor and then you have it attached to the compression chamber with a shaft and all those bearings have to be properly lubricated, so bringing liquid into the compressor. While it's running is bad, but that's not slugging.

On most of the refrigerant cooled, compressors that we work on most the compressors, we work on our refrigerant cooled, compressors right now there is such a thing as an air-cooled. Compressor and you'll see this in refrigeration. In some cases and in an air-cooled compressor, you have a motor, that's completely separate, like it doesn't do what we've been talking about here, where the refrigerant dumps into the crankcase. So it's got this separate thing.

In that case, it's exactly how you imagined it initially goes down that suction line hits that head gets pumped out. Well, if you have any liquid in that sucker, it's going to blow that head to high and I've kind of wanted that before, like you, show up and you got zero sub cool or superheat and a frozen evap and it's running and I'm like. Oh, this is compressor even I was it surviving, yeah real, quick. This won't take very long.

I want to mention to you about AM rad American radionics they're, a company that makes capacitors here in the US and when I heard that they manufacture capacitors in the US. I thought: well, maybe they assemble them, that wasn't sure, but I went up to their factory and it is a legitimate factory. I mean they make these things from scratch. They actually wind up the capacitors and he showed me all the different ways that they can make.

Multiple capacitors from a single winding in the capacitor from a single plate. That's wound up. He showed how they make the turbo 200 capacitors, which is the only universal capacitor that exists on the marketplace where you can replace multiple sizes with a single capacitor. It's a great convenience product, so this is what I want to say.

Real, quick and rad makes great convenience products, products that save you time and save you money, because you don't have to make multiple trips reduces the number of parts you get to keep on your truck and a lot of you will say: yeah put your other prices. A little more but here's the thing they also make the best product in the marketplace, and this comes from my experience over the years of seeing how well these things last out in the field. No product is going to have a zero percent fail rate. I mean it just doesn't happen right, but I've seen am rad capacitors, just incredibly long periods of time.

I saw a photo just a couple days ago from somebody who found one that was from 1995, their 20 micro farad capacitor from 1995, and they took it out of a system and retested it. And it's exactly 20 micro farad's today and it's because they do a really good job, not only with how they make them, but how they test them. They test every single one before it leaves. I saw the processes that they use it's an excellent excellent product.

So not only do they make a very convenient product, they make it well, they make it in America, a family-owned business since 1939, the exact kind of business that I'm excited to work with and support. So if your local supply houses don't sell imrad, capacitors and turbo 200s, then I would suggest that you go up to the counter and say that that's what you want to see on the shelves, because it really is a great product and it's gon na make. You look good with your customers. It gives you a story to tell when that customer says.

Why is this capacitor cost so much? I can buy it online. You say you can't buy this one, not for the price that you're looking at, because this capacitor is american-made comes with a five-year warranty and it's better quality than anything else out. There gives you a great story to tell your consumers and as well as a great value to them so consider looking at the AM rad American radionics capacitors next time. You're at a supply house, so getting liquid into the crankcase is still a really bad thing.

But it's more of a long-term bad thing, and so that's why, when people talk about I've charged systems by beer-can cold, my whole life - and I never had no problems well yeah, because you don't have a problem like tomorrow or even next month. It's just the compressor. Fails on you three years when it would have normally lasted 12, you don't know whether or not you cause damage to it or not, based on a charging problem. Now, even more common in a compressor is that you have a flooded start and a flooded start is where you have refrigerant liquid refrigerant that migrates to that compressor, crankcase, while it's off, and then you get that liquid in there with the oil.

When that thing starts, it has a little mini explosion, because all that heat and all that inertia all at once and that liquid starts boiling off really quick and that oil all gets the foams and gets thrown out of the compressor. And that causes a lot of damage in most cases where we see oil related damage and the type of equipment we work on is due to flooded starts as much as it is due to flooding when it's running. Those are both real considerations and that's why we have crankcase heaters in a lot of cases. Cranky's heaters are what help solve that problem, because when you have and that's why cranky cedars become even more important and heat pumps because in he pumps were operating them even when it's really cold outside.

So this goes off right and then we're about to start it up when even the say it's 20 degrees outside well, the coldest point in that system is that compressor, let alone the fact that the refrigerant oil attracts refrigerant anyway, so just by its very nature of Being foreign oil in the vapor pressure there, it attracts refrigerant into it plus add in the fact that it's, the coldest section it's gon na definitely condensed liquid refrigerant inside there. So using a crankcase heater helps prevent that. It's probably the easiest way. You can also use a pump down solenoid and some other things, but that's a compressor.

Okay, so compressor takes this vapor and that's very. I want to use the opposite of dense being very loose. It's like these molecules, they're separated and it's low temperature, and then you take it and you throw it into the head of this compressor and you slam these molecules together, pin them together, yeah and then obviously, as the pressure rises. It goes against the discharge line.

Pressure right, I'm a buns, the pressures above the discharge line pressure a little opens up, allows the vapor refrigerant to flow through into the discharge line right right. That is the traditional reciprocating valves. That's when you have valves in it and so the pressure in the head. Obviously has to go higher than what's in the discharge line like here and just said, and the reciprocating compressor, and then it opens that valve and that refrigerant goes out in a scroll, it's more continuous, and so it actually just because it's sealed all the way back Through as it gets high enough pressure, then it just naturally goes out of that compressor and a lot of Scrolls do have a discharge check valve which disallows it when it shuts off from that refrigerant from going back into the head.

But it's more continuous compression at that point, the vapor who don't leave the scope compressor through the middle? Oh yeah, the center of the scroll is the highest pressure point yeah. So it goes out from the larger chambers in the outside and then he's continuously compressed until it goes to the smallest chamber in the center and then discharged out one of the real kind of magic things in air conditioning. Is this idea of why we go from this cool temperature suction line? You know if you grab the large line, I mean even for a complete amateur one of the first things. You'd probably do is touch the different components in the system.

Don't touch the discharge on either compressor head, otherwise, you'll burn your hand, but you touch that suction line, which is the large line and a split system that goes in between the inside and outside, and you feel that it's cold right, it's the joke. Beer can cold and a lot of times, it'll condensate. Then that's one of the kind of qualitative tests that missions will do is they'll grab that line and they'll say: okay, the system is running or whatever, and so new guys see that, and so they grab that line. Oh ho that's cold, and then you look at the discharge line, which is just on the opposite side of that compressor and it is blazing stinkin, hot right and so a lot of technicians think that there's like some magical thing that happens there.

That makes it go from cold to hot, but here's the thing to understand that all of the heat, that's leaving the house all of the heat that you're taking out of the house cuz, that's what you're doing with a refrigeration circuit you're taking heat from a place That it's unwanted, namely inside in the case of cooling, you're, taking it from a place, that's unwanted and putting it in a place where it's unobjectionable, that's the actual technical definition, they're removing it to a place. That's unobjectionable so you're taken from inside putting it outside when you're cooling. All of that heat is coming down that suction line that freezing cold sweating exactly you grab that and you think, oh that's the cold line that must be pumping cold into the house. In fact, if you want a good joke, have you seen the video from this old house that they're AC expert from this whole house Moe? I don't know what the key word you'll use to find it, but it's pretty funny cuz.

He describes it that way. He's like you, can see here this cold line. We call this the suction line, and this brings the cold into the inside coil, he's literally going backwards down the circuit, because intuitively that's how we think. We think that somehow the suction line is cold, so that must be pumping cold into the space.

And that is not how it works. It's important first to sort of pin down why we think the way we do about this. We have this imagination that somehow this cold line is indicative of the cooling capacity of the system in some way, and the reason why we have this imagination is because we use our senses all the time to dictate what is hot. What is cold right.

I used to always say - and I think I probably even said in the earlier versions of this podcast, I used to say, there's no such thing as cold. Jim Bergman sent me a message after I said that and he's like that. Actually, actually, there's no such thing as hot. There is such thing as cold, and this is something that I've come to.

The realization of is that so much of what we do is weíre measuring comparisons of energy. So when we say something is one degree right, one degree is a measurement of temperature and temperature is average molecular velocity and we're measuring it in so we would say we have water, that's 40 degrees, and then we may have it. We heat it up a little bit and goes to 41 degrees right and the definition of a BTU is the amount of heat it takes to change the temperature of one pound of water by one degree Fahrenheit right. We use these kind of like measure of comparison and the degree is an example of that, and so when I say that, there's no such thing as cold cold is not a thing that we can point to.

It's not an energy state in that sort of comparative way, but there is such a thing as cold and cold is the absolute absence of any heat, and that is absolute zero. So when you talk about a point really the only point on the scale that we can point to when we're talking about heat, is that zero point right? Because there is no maximum point of heat, you can keep adding heat and the temperature can keep going up and up and up forever right. But there is a point of origination and that point of origination is the point of there being no heat. It's a hypothetical point, of course, because we can't achieve it, but it's a point at which no heat exists.

So in one way we can say there is such a thing as cold and cold, his no heat, but everything other than that we're doing comparisons. So when we say something is hot or cold, we're comparing it to the temperature of our bodies right about 99, 98, 99 degrees right, and so when we feel something that's lower than the temperature of our skin of our bodies. Then it feels cool to us, because our body gives off heat to it right and we feel something that's higher temperature than our bodies. Then we feel it as hot because we're absorbing heat from it, and so one of the kind of universal rules really there's a couple.

But one of the universal rules that we talk about all the time is hot, goes to cold mm-hmm. A better way of saying that I think when you apply all the different elements of thermodynamics is just that energy tends towards Equalization or whenever you have energy differences. Differences in energy States, they tend to just stabilize and create a median point. So that's a way of thinking of is lightning.

Correct. Lightning would be an example of that, and in that case it's electrical potential. So you have this electrical pressure that wants to be equalized. It's the same with humidity, high humidity and low humidity.

High humidity goes to low humidity. High pressure goes to low pressure. High temperature goes to low temperature, that's ways of thinking of different energy states. High voltage goes to low voltage, and so when we've grabbed a suction line and we feel it as being colder than our skin temperature.

We think well, that's cold right, but the truth is: is that it's really not that simple? Because what we're doing when we move heat from inside to outside is we're leveraging this really powerful system. That is the change of state of matter from one state to another, and that's really the secret sauce in what we're doing in cooling a home and especially in the we're gon na focus on the air conditioning side here, because we could mix it up with heat Pumps but let's keep it stuck on the air conditioning side as a mini bonus for this episode, we did go off on a little side, note on vrf vs. ductless and some of the differences, and so that's what this is. If you want to listen to this, this is only take a couple minutes, but it was kind of off subject.

So I put it here at the end. Do you know the difference between vrf and Douglass's? I give it was a b. Rf is the variable refrigerant flow. Variable, refrigerant, flown right and Douglas is just like the mounted units on the wall right all right.

So if you go to a commercial site, this is gon na, be a very meandering conversation, so just get used to, but there's gon na be lots of value bombs backed in here everybody listen for the value bombs, so a V RF system. If you go to a commercial site - and we do meant to be she's, emit speeches, so Mitsubishi has a line called City, multi and so you'll go into commercial buildings and you'll see units that look very much like ductless heads in the building right it'll be all Over and they all connect back to these large condensers, they call that V, RF variable refrigerant flow. Now, why don't they call it ductless? Well, the main reason they probably don't call it. Ductless is because they're, not all ductless.

A lot of the heads are actually ducted. Mm-Hmm, the most common would be like a low static pancake, so it sits in a room and just has very, very short ducts attached to it, and so it's still duct it. It's still concealed. Maybe a ceiling cassette, there's just different types, and so they don't necessarily calm ductless, because they're, not all ductless, but how we define the difference between v, RF and ductless, because we all work on an mitsubishi, MXZ unit that has multiple heads.

We do this a lot to have a single condenser, multiple heads. We still call that ductless right. We don't call that V RF. Well, that's where the line becomes fuzzy, so we call something v RF when it has multiple heads, usually more than two and generally speaking, most manufacturers call it vrf once it's three-phase yeah, that's primarily the decisions not because it has multiple metering devices.

They all have multiple metering devices you're right yeah everything has to have its own metering device, but another distinction - and this is why I was going down this rabbit trail - is that most vrf systems use a true liquid line in between the condensing unit, the outside unit And the branch box and then the metering devices are either in the branch box or in some cases they're in the heads themselves, and this is a distinction. It does vary slightly based on brand right, but in a lot of cases, what you're gon na see is a liquid line in between the condenser and a branch box and then from the branch box to the different vrf heads and at that point the branch box May have a metering device in it metering devices in it or it may not, and the metering devices may be at the fan coils at the air handlers, but with the ductless it's gon na be in the condenser. This is a case where we see an expansion line, isn't a ductless unit and that's between the outside unit, because the metering device is outside. You don't have a true liquid line, and so, when you work on a ductless unit and you insulate that what we would traditionally call the liquid line, the small line.

That's the reason why you're insulating it is because the pressure drop is at the condenser, and so that is a low temperature line, make sense Karen yeah. And so, if you're working on a V RF system, where you have a branch box and the main device is the branch box in some cases you don't have to insulate that line. In some cases you do depends on two pipe three pipes: there's different types of applications there so to follow your manufacturer specifications, but when it's a liquid line, you generally don't have to insulate it and when it's an expansion line, you generally do because the liquid line Is near ambient temperature in most cases and an expansion line is obviously lower than ambient temperature because it's after the main, your device. Those are a few of the distinctions again to kind of tie that dog v RF vs.

ductless ductless is usually metering device outside limited number of heads limited length. Also, that's a challenge with using an expansion line. Is that you're really limited in the amount of distance? You can go, whereas in v RF you need to be able to go a really far away and it's easier to pump liquid and not have losses than it is to use the expansion line so with v RF. It's generally three-phase many heads and the meter devices are either at the branch box or the air handler ductless, it's fewer heads single-phase generally, although some brands do make a single-phase of e RF, which is really just a single-phase unit that uses a branch box and multiple Heads there are some variances there, but gives you an idea of the ranges of what they call those things.

So the basic refrigerant circuit is one of the cornerstones of what we do. There's so much both application and theory in our business and electrical application, electrical basics and diagnosis. That's a really important part! I talk about that. A lot on the podcast, but this series part one and part: two is really the basics of how we move heat around.

What we do every day with refrigeration - and this truly is refrigeration, as like I've mentioned air conditioning, doesn't require refrigeration. Willis carrier made his first air conditioner without using the refrigerant circuit at all, but so much of what we do focuses on the refrigerant circuit and that's what this was all about. So hopefully you found that helpful. If you have any feedback for me, you can always email me, brian, be rya and at HVAC our school comm.

You can find all of our daily tech tips and quizzes and calculators and all the resources that we have all the podcasts, all the videos, everything we do. You can find it HVAC our school comm, there's a search box there on HVAC our school comm that you can use to find anything. So in this episode I talked a little bit about saturation and how that's often misunderstood thing. If you want to read more of unsaturation, if you want to read up on the five pillars of refrigerant circuit diagnosis, if you want to read up about evacuation, checking the church without gauges, all those things popular topics, we've talked about on the podcast and also in Writing and you can find those both at HVAC our school comm as well as if you want to see more about the other podcasts that we do.

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