Right thanks for joining us again on the hvac school podcast eugene thanks surprisingly brian brian always a good time to uh spend some time in chat. Yeah. That's's the joy of this and it's uh. This is really my excuse for having a podcast as i get to talk to people i look up to and uh have enjoyable conversations.

So this will be fun um. So to kind of just kind of tee off this conversation. You wrote a book and it's one of many books that you've written and it is about pressure enthalpy. Which i think a lot of technicians.

Maybe learned a little bit about in school maybe haven't learned anything about it why did you choose to write this book well. It's it's my students at the college actually pushed me to write it because this is a topic that i've been passionate about for for decades. This is something that i started messing around with back in the mid 80s. And it was a like i said a topic that i really gravitated to i really liked the physics and the you know and how the whole process works out so when i was teaching this concept.

This topic at the college. My students were asking me well professor where where is this in print and it's in print. But it's not in print because a lot of these formulas and calculations are embedded in in ashrae handbooks. Which are you know higher level books you know geared toward engineers and my students will push me like professor.

We need something in writing we need this written you need to write a book on this and and if you look at the dedication page of pressure enthalpy without tears. It's dedicated to my first graduating class at suffolk county community college. Because without them pushing me to actually write it it probably wouldn't have come to fruition yeah. So when you talk about pressure enthalpy without tears.

You know i immediately want to cry because i don't like math uh it feels like engineering and so i think uh me and a lot of technicians. When we bump up against this. You know pe charts. And all this.

The thought is sometimes isn't this just for engineers. I mean is this even for us as technicians yeah well in its original format. It's absolutely for engineers. The the math behind it is kind of complicated.

But brian is that there's a big difference between a technician. And an engineer as as hvst technicians. We're out there to restore the system the way it was before it failed. It's not the hvac technician's job to engineer a system so when you're engineering a system you're searching for perfection and you're looking at ideal systems.

So you know for example ashrae. When they when engineers design a system using ashrae standards. You're looking at a saturated cycle. Where there's no superheat.

There's no suction line super. There's no condenser sub cooling. It's a very ideal system and technicians you know that's not the real world for us. So our job is to restore the system to what it was doing before it failed and the pressure enthalpy without tears concept was to take these engineering level concepts and repackage them in a way that's going to benefit a technician out in the field.

So it's really really neat. And i get a lot of flack from from engineers. And you know without tears pressure. Enthalpy is supposed to be loaded with tears and the the math.

That's in this book. It's really nothing more than addition subtraction multiplication and division. It's basic math. And the concepts in the book are really just an extension of things that we're already doing in the field.

So we get that a lot. It's like oh. This is complicated you know this is so hard to do and it's really a minor minor extension of what we do you know for example. When we install a system and we start it up and you put it in a four ton system.

How do you know you're getting four tons. You know we stand on a chair and and we feel the air coming out of the supply register. Oh yeah. That's four times ah.

It's probably four and a quarter you're getting extra how do we know right by by measuring temperature differences and and feeling airflow. We can't determine capacity. We can't determine efficiency. What if a customer buys you know a 20 seer unit.

When you start that system up are you getting 20s here is that system operating at the capacity and efficiency that that system is intended to operate. And what's neat is with with the concepts in this book you can actually determine system capacity system efficiency. So you can really really drill down and determine and verify that the system is doing what the system is supposed to be doing yeah. And i also love that this goes hand in hand with psychometrics without tears.

It really is um. It really is the perfect companion to it because when you even think about a word like enthalpy and i'm going to ask you to kind of define that for us again. But but when we as technicians over the last several years there's been a big kind of shift. Where we are starting to look at things like looking at you know wet bulb temperatures and supply ducts and so you know with with accurate enough psychometers that we can start to kind of understand this so on the air side.

We've started to kind of think about enthalpy. We started to think about total heat content. And that sort of thing. But on the on the pressure refrigerant side.

You know how do you think about it in that how does that relate uh and so i gotta riff on that a little bit you know what does enthalpy even mean in this context. Well. Yeah. What's really neat is enthalpy is just a fancy word for for heat and heat should not be confused with temperature.

I mean temperature is a level of heat intensity. Whereas. Enthalpy is a total heat content. So we measure temperature in degrees.

And we measure heat content in btus per pound or b2s per per unit. So if you have and and this is an example that's in in the refrigeration air conditioning technology book that we've used for forever. If you have a one pound sample of water and you heat. It one degree right you put some heat energy into that water but now if you have a thousand pound tank of water and you add heat and you increase its temperature one degree well which water sample has more heat content and obviously the thousand tank.

You know the thousand pound tank. Has and and it's kind of interesting. You mentioned psychometrics and the two are really really interrelated. They really do go hand in hand.

Because if you're a fan of psychometrics and you're a fan of all the formulas and discussions that that you and i have had previously you can calculate the capacity of the system on airflow and say okay well the air is giving up x number of btus per hour you know making the air cooler. We're dehumidifying the air and we're cooling air well if an air stream is giving up heat to cool. It and dehumidifier. Where is that heat going well that's the heat.

That's being absorbed into our air conditioning or refrigeration system into the refrigerant. So. If you know the capacity of a system based on psychrometrics calculations. Then you know what the capacity of your refrigeration system is you know how many b2s per hour.

That evaporator is absorbing and using that psychometric chart. There are also some really neat tricks where you can determine from that psychometric chart. What the temperature of the boiling refrigerant is in the evaporator. So there really are some some really nice links between the psychometric chart and the pressure enthalpy chart as a matter of fact when when my students at suffolk county community college.

We're taking their final in one of their last courses before they graduate. They're given a system and they're given psychometric charts they're giving pressure enthalpy charts. But they're not given enough information for each chart to complete one or the other and they actually had to work back and forth between the two charts to get a complete answer and to troubleshoot so using the psychometric chart using the pressure enthalpy chart together you can actually identify where a system problem. Lies is it an air flow problem is it a refrigerant problem.

When you plot. These things out it really jumps out at you and when i teach i always let my students know and i guess lecture at colleges across the country and it troubleshooting really is a game it really is a game that can be fun troubleshooting is you know it's where is the problem where are you hiding. And it's kind of a neat little game of hide and go see in fact that's actually a game. We never titled it but we played a form of a troubleshooting game.

When i would ride with uh whoever. I was was teaching in the field um. Because most that's how i started in in doing uh. Some some teaching was just you know the guy who's writing with me teaching them and we would we would play this game.

Where you know i would give a set of of information um to start with. But then they would have to ask the questions in order to fill in so um. You know kind of role playing the customer technician interaction. But also kind of acting as the gauges and just sort of shouting out.

What the what the measurements are and then they have to figure out what the problem is it really is a game and actually uh that's what i love about this trade is that it's it's kind of like solving a puzzle. It really is it really yeah so let's talk about the chart itself. So. When we talk about the the pressure enthalpy chart.

Or the pe chart. What is it like what is it what is it for well you know we mentioned before we were talking about the difference between enthalpy and temperature. And we all have either in our pockets or as an app on our phone. We have pt charts so that's pressure temperature and every refrigerant has its own pressure temperature relationship.

So you look up the refrigerant you're working on and you find this saturation pressure. And you get the saturation temperature or vice versa and a pressure enthalpy chart is exactly the same the only difference is instead of temperature. We're talking about heat content and every refrigerant has its own pressure enthalpy chart so your pressure temperature chart represents saturation you know one pressure one temperature or a temperature glide if you're dealing with blended refrigerants and that's one aspect of this pressure enthalpy chart. There is what we call the thumb print curve.

It's a saturation curve on the chart in the middle of the chart and that represents your pressure temperature chart. But on the left side and the right side of the chart are your sub cooled liquid regions and your superheated vapor regions. And what's really really neat with the chart is you by after you take a few simple pressure readings and temperatures things we're already doing on a system. You can plot these points on this on the chart.

And you create a visual representation of the entire system so picture. What a technician is doing in the field now they're going outside to the condensing unit. They're gauging up they're measuring outside ambient temperature. They're getting operating pressures.

Then they're going into the house. Then they're climbing up into the attic to evaluate the the blower so to get a full picture of the system. Our technicians really have to go from place to place to place to place to place and then put all these pieces together in their brain about what's going on with the system. And what's neat with the pressure enthalpy chart you get the whole system.

In one place. You create one picture. And it's a it's a right trapezoid. Very very basic shape and if you understand what that shape looks like on a properly operating system.

Then you look at the shape that you plotted and by looking at changes in the shape is the trapezoid skinnier than my design is it thicker is it shorter is it shift it to the left shift it to the right. I can actually troubleshoot that system and determine exactly what's going on with that system and whether or not you go through the calculations. And again. The calculations.

Basic addition subtraction multiplication. The basic math operations. Even if you don't go through those calculations. If you understand the lines on this chart you could say well what's going to happen if all right oh if my outdoor coil gets clocked well that's going to cause my highest high pressure to rise that's going to cause this picture to become taller.

That's going to cause the right side of the plotted picture to move to the right. That's going to cause this to move that's going to cause what we call our heat of compression to increase well that's going to cause my coefficient performance to drop so whether you actually go through the numbers or not you can explain why a dirty air filter is going to cause a system to malfunction for example again not to get too crazy yet. But if you have an air filter that gets dirty all right what happens less heat gets absorbed into the refrigeration into the refrigerant low side pressure drops my net refrigeration effect is going to get smaller. My heater compression is going to get bigger my mass flow rate is going to go down so now i'm moving less refrigerant through my evaporator coil.

And my refrigeration effect is now my capacity is going to go down. So we didn't talk about numbers yet so what's neat is if you understand the concept. If you understand what the lines on the chart do and you and i have had a similar conversation when we were talking about psychometrics. If you understand what the lines on the chart mean.

If you understand what the lines on the chart do whether or not you make the calculations you'll say okay. If i humidify an air sample. The density goes down all right on a psychometric track well the same thing with a pressure enthalpy chart. If you understand what the lines.

Mean what they do then regardless of whether you do the actual calculations you're going to understand how the system is going to respond the laws of physics don't change the laws of chemistry don't change when you expose refrigerants to certain conditions they're going to behave. Predictably. And that's what it's all about. People.

Think. Oh wow. You know you know this. You know refrigeration stuff is magic.

No. It's on a chart. It's predictable. It's absolutely one one really interesting thing because again i keep bringing back the parallels between pressure enthalpy and that chart and the psychometric chart.

But one thing that is different and is very interesting about the pe chart is that we're actually plotting um. The entire system. So we're going through and we're that shape that we're drawing on this on this chart is about looking at that entire system and how it's operating. Which is something that we actually rarely do on the psychometric chart.

It can be done and is done in some cases. But you could do the same thing where you would actually go around and actually look at you know air under different conditions or as it changed as it may be you know how it went into the duct work versus. How it came out of the duct work etc. Etc.

But in the pe chart. It's very unique in that way. Where we really are we're almost getting a almost getting a look at time um. We're looking at a fluid that's that's moving throughout this entire system and almost looking at the life cycle of that fluid and the heat.

That it contains. Which is uh. Which is really fascinating and is very like like you said. It's it's very tactile.

It gives you this visual representation uh in a shape that you kind of you kind of get a feel for it. Which is really uh interesting and uh useful yeah. And you know what just to you know to expand on that the top and the bottom lines of this chart this this right trapezoid that's created represent the high side pressure and the low side pressure now for us as technicians. We're not engineering a system so when an engineer and i've had a lot of engineers look at the book and actually love it because it makes it easier to understand for their for their people.

But there are pressure drops in condenser coils. There are there are pressure drops in evaporator coils. So the pressure is not constant. But for us.

As technicians again our job is to restore the system to what it was doing before it failed. So we assume that the high side pressure and low side pressure are unchanged. They're constant. So the top and the bottom lines of that pressure enthalpy chart are perfectly parallel to each other and the compressor.

I mean we have a line entering the compressor and an engineer will look at it and say well that's not what happens yeah well we know that's not what happens you know when you put on your engineer hat. But when you put on your tech cat. This is really really sufficient to give us an understanding of what's happening in that system. So yeah we set a right trapezoid.

Four sides well we have four main system components in our air conditioning system. We have compressor condenser metering device evaporator one of those sides represents the compressor one represents the condenser one represents the metering device one represents. The evaporator and you can look and say okay well this is what's happening in my condenser this is what's happening in my metering device this is what's happening in my evaporator and this is what's happening in my compressor and you're looking at it as we've said a few times already as one whole picture and you're treating the system as a system you're not evaluating each individual component. You could let's say you rip the suction line insulation off the off the suction line.

Which is where suction line insulation usually lives and you plot that system amount you're going to see that that shape changes. There is a line. There's a short little line segment on that pressure enthalpy plot between the evaporator and the compressor that represents the suction line and if you re and we've done this on hundreds of systems. You know i had the the opportunity of writing directing and teaching a program at a college and you know having a lab at my disposal was great so in the in the 12 and a half years.

I was at the college. I mean we literally lab tested hundreds of systems and we were able to tweak formulas and get everything really nice. So it works really really beautifully. And yeah.

You rip the suction line insulation off the unit. You're going to see that that little line segment. That represents the suction line went from from this to this and you can see it you can actually look at that picture and say this is the problem so you know the laws of physics you can't break you can't change. But that picture is is absolutely dynamite.

We did a an energy audit down in miami. And it was at a marriott property. And the students realized that the heat on the roofs was was really really killing the insulation on the suction lines. You know all these little split units.

And the students took readings from the system. And they plotted everything out they were able with the pressure enthalpy chart. They were able to calculate the end the hourly operating cost of that system how much it costs to run that system every hour and then they repair the suction line insulation and once that sucks line insulation was repaired. We waited till.

The next day until the you know outside ambient temperature was about the same they retook a set of readings. They replotted everything they recalculated and they realized that they were saving two cents. An hour on operation and at first my students were like well what's the big deal about two cents and we're like well how many units does this you know uh does this property have and how many cooling hours a year do we have in miami and they did the math and the savings were absolutely astronomical and it doesn't take a lot of skill or you know to replace suction line insulation and that was one of the first things that the staff at marriott took once we left they replaced all the insulation on all the suction lines. So yeah.

It's it's a game of pennies when you're talking in the scheme of things. But yeah with this chart they were able to calculate how much it cost to run that unit for one hour and then they could calculate how many hours a year. And what the percentage was and you know it's really. It's a really really powerful tool and like i said before it's nothing that we're not already doing we're already taking pressure means we're taking temperatures now it's just putting them on a chart and once you have all the information maybe two minutes to draw a box on a chart and then what i did is i took a um.

I took all the formulas and put them in an excel spreadsheet. So all i had to do was enter highest pressure. Low side pressure condenser out of the temperature compressor in the temperature evaporator outlet temperature. Calculate the horsepower of the compressor you know the actual horsepower not the nameplate and boom.

Everything would populate you know the net refrigeration effect. The heat of compression. My coefficient of performance. My eer you can calculate eer from this chart.

What the capacity of my system is how many btus per hour. How well it's doing i mean what the capacity of the compressor. How many cubic feet per minute is that compressor moving and if you have that documentation. I mean let's say for example you have the specs on the compressor on the system.

So you know what the volumetric capacity of the compressor is x number of cubic inches per minute you can work backwards and determine what the evaporator capacity is what the capacity of that system is so what's neat is you can work backwards and forwards with this you know with these formulas based on what information. You have you know and and it's it's not magic a lot of i've worked with a lot of tool manufacturers you know you have smart manifolds out. There you know there are a lot of manufacturers that make smart gate. Gauge.

Manifolds and i i consult with all of them and a lot of the algorithms and formulas that are in these units in these devices are what's in this book. The the formulas that are embedded in in those instruments are formulas that are are in this book. So it's kind of a neat thing yeah. It's it's uh super fascinating and i was going to ask you next about what uh.

What you need to take in order to to plot it. But i think you just answered. All the questions right pressure right low side pressure condenser outlet. Temperature evaporator outlet temperature compressor inlet temperature.

Now the only thing is on the pressure enthalpy. Chart the pressures are expressed in absolute so. Yes there's 147. But you know what we're technicians.

15 is more than good enough again we need to be in the ballpark. So. If you take an operating pressure. And you're looking at 120 psig.

At 15 135. That's the number that gets bought that's one of the biggest mistakes people make when they plot is they take gauge readings from the field and they put it directly on the chart and they and they forget to convert to absolute. So yeah. It's high sub pressure low side pressure condenser outlet temperature evaporator outlet temperature compressor inlet temperature now again i mentioned compressor voltage current you know actual and then meters that we have now give us the power factor.

So that's going to give us the actual wattage and then we can calculate the actual horsepower. And and the more accurate the better your numbers are that you put into this the more accurate and reliable your readings are gonna you know your calculations are gonna be you know what do they say with computers garbage in garbage out same thing. You know if you take the time and get good accurate. Reliable readings and you put them into these formulas.

You're going to get reliable answers out. And that's what it's all about. And there's um yeah. It's magic.

It really is it's kind of neat that you can just take one additional step from what you're already doing and just get all this information. And we used to do this you know i was fortunate enough to have owned three service companies in new york and we would plot these things out on every system every time. We did an annual preventive maintenance call on a client's piece of equipment. We took the we didn't ask the text to do it in the field.

But we had a checklist and they had to provide us with all this information and when they came back to the office with this information. We actually plotted the system out and it was all automated. We kind of had it in you know a different worksheet or spreadsheet type things. And it would become part of the customer's file.

And you could actually predict system failure you know back then we had a lot of reciprocating compressors. And and valves on reciprocating compressors on water systems would leak over time and we could actually predict we've done it on numerous occasions. We actually predicted compressor failure and we go to our larger customers. And say listen you're going to lose a compressor.

We don't know if it's today tomorrow next month or next year. But this compressor is showing signs of increased valve leakage and we're going to need to schedule a valve job on this compressor and schedule. Downtime is always less expensive than you know that emergency service emergency repairs. And it's really really a neat way.

It's kind of like that magic eight ball for hvac. You know where you can actually you know look at what. The system is doing and kind of predict what it's going to do yeah. It's and it's also just a really great learning tool as well uh.

You know we're talking so much about how you can use it as a technician. But it really helps you to understand the operation of the equipment in terms of that enthalpy side of things and we often think in terms of of pressures. You know text learned that very early on to think about pressures. But this helps you really understand heat and how it's moving to the system.

Which is really really cool um. The biggest question that i think anyone who kind of dives into this and you know you know most of it makes sense like you said you know each line represents a component in the equipment. And you know you kind of get to it it's all making sense. It's all making sense and then you hit these things called the constant entropy lines and it's like okay all right what what is this because you know i remember hearing in high school.

You know like entropy is disorder. I mean what what what is this what is what's going on if if you if if i talk to you about the number of questions. I get the number of emails. I get the number of phone calls.

I get about pressure enthalpy the vast majority of them are about lines of constant entropy and the conversation always starts out professor silverstein. I googled entropy and it talks about the state of unrest. The state of decay and i have no clue what that means for hvac and when you look if you think about decay and if you think about decay when something decays. The process says you don't undecate you know once you decay.

It's decay once damage is done they talk about you know the world after people and they talk about mother nature reclaiming. The planet and so when we talk in in terms of refrigeration and air conditioning. The the lines of constant entropy refer to the compressor so off to the right side of this chart are these steeply shaped steeply sloped lines and those are lines of constant entropy and i can explain entropy to an hvac technician. In one word and that's reversibility.

The compression process is 100 reversible. So for example if i give an example of a reciprocating compressor picture. Refrigerant inside a cylinder picture. The valves closed and as the piston moves further into that cylinder the volume of that refrigerant is decreasing and the pressure is increased if i then move that piston back to where it was before i started the pressure in that cylinder is going to be exactly the same as it was when i started so the process of compression is 100 percent reversible.

And if the process is 100 percent reversible then we follow one of those lines of constant entropy those lines of constant entropy refers to the reversibility of a process. If we cross a line of constant entropy that means that the process is no longer reversible and we've just said that compression is 100 reversible. So notice when i said what information you need to plot these things out on the system. I said you need high side pressure low side pressure condenser outlet evaporator out and compressor inlet.

If we have the compressor inlet temperature. We automatically have the compressor outlet temperature the discharge temperature. Because when we find where that point is we follow a line of constant entropy up without crossing it because we can't cross. It.

And if you could figure out a way to cross a line of constant entropy call me because you've just shattered the laws of physics and where that line you follow that line of constant entropy up and where that line crosses your high side pressure that point. Where your refrigerant is leaving your compressor and i and i stress this because if you have a uh. Let's say an old low side dome compressor right where you have a i'm going back to like an ultra comp. So you know tin can the discharge line of that compressor is not where the copper line is leaving the shell that that discharge line is deep inside because the shell of that compressor is filled with low side gas.

And there's a discharge line inside that shell with a coil of tubing. So that refrigerant that's leaving the shell of that compressor is already desuperheated. It's already cooled down so. If you take that temperature as a discharge chamber.

Try and work down you're going to end up underneath. The saturation curve. Which is a no no so i always say grab the inlet of the compressor follow the line of constant entropy up so remember so yeah one example i give with with reversibility is if you have an induction type cooktop in your house. Take an ice cube put it on top turn.

The heat on at some point. That ice cube is going to melt on that induction. Heater well now turn the induction heater setting back to where it was before the water. Doesn't become an ice cube.

Again right. The water is still water well. That process is not reversible. So.

If you plotted that process out on a chart. Where you had lines of constant entropy that process of melting. The ice cube on that induction heater is going to cross those lines. Because the process is not reversible.

So when you what i always tell people when you when you embark on plotting a system out on a pressure enthalpy chart. And it says lines of constant entropy. I always tell cross that out just put reversibility lines. You know and you can't you know compression is reversible.

You know you're going to you know compress you're going to expand and it's always going to be along one of those lines or parallel to one of those lines. But yeah. It's cool you brought that up because the vast majority of questions i get about that chart from technicians from teachers is about that line like what is that you know is that why is it decay and unrest. And you know it sounds like there's going to be like a mutiny in the air conditioning system right yeah.

No that's cool you brought that up because that's that's a major major concern. Yeah. Your explanation is actually helpful mine not so much i i say a good example of uh of entropy and an air conditioning system is when you let the smoke out of a motor. And it's really hard to get it back in would that work it's not reversible.

It works and you know what at the college. We've let the factory smoke out of a lot of components. We've let the fact transformers out of motors. Yeah.

My students have become actually really really good at that yeah you know right it's tricky to get back. It's a quick aside you know i was actually shocked the um you know after we did our pressure our our psychometrics podcast. It's kind of really neat you meant we mentioned the school. But it was kind of wild.

How many of my old students reached out to me they commented on youtube. But they also sent me emails and called me because all my students have my my phone number and they actually would text and say i saw the podcast. It was great and it's really nice to know that they're that they're still in the industry that they're they're active in the industry. So that was actually really cool after after we did the psychometrics podcast.

That we have a lot of people who who got to witness this firsthand and got uh are still into it which is neat. They're still into it because they learned how to do it uh without tears. So if you would if they would have learned it with tears. They would have just rejected it you know probably become underwater basket weavers.

There you go that's awesome um. Yeah. So you've already mentioned you know a lot of the things you can do with it as a technician. That's the thing that i think a lot of people maybe don't get is like what where's the value as attack and and it is one of those things that it's probably not something you're going to do on every system uh you know as a tech out in the field.

But it is something especially when you're maybe having a difficult or interesting uh troubleshooting project. That's really helpful and especially when you're learning. It it's it's something that i would definitely recommend for people who are you know maybe teaching a trainee or if you're a contractor and you're you're wanting to kind of get that that strong underpinning of understanding of how it works as part of a very full understanding of the compression refrigeration system. But like we mentioned before alongside things like psychometrics it helps you just understand you know we're dealing with fluids here right and we're moving heat around with these fluids and one side we're doing it with air on the other side.

We're doing with refrigerant and getting that full understanding is really a beautiful thing and and helps i mean i was i was joking. But it actually does help people stick with the trade because uh when you have some we have some passion you have some curiosity. It actually does make it a lot more enjoyable at least. I think so you know what it appears to be really really complicated.

But once you drill down it really is not that bad since high school all right. There's yeah. I went just i graduated from high school in in 1883. And the popular thing in high school was this and i always wanted to learn how to solve it and everybody was trying to teach me how to solve it and how to work with it and how to you know.

And it always seemed complicated too complicated too complicated too complicated so i would try throw it away for a couple years pick it up throw it away for a few years well i'm 56. Now i graduated from high school at 17. So 40 years later it was probably about a month ago did i say you know what and i had this sitting and i said let me try again and i watched some videos and i spoke to some people and now i looked at and went you know what it's really only it's really only two moves that you're just repeating over and over again. It's really not that bad so my advice to you and technicians and contractors and even students.

If you've looked at pressure enthalpy before look at it again with a fresh set eyes because it's really it's addition subtraction multiplication division. And it's really just it's powerful you know and it'd also be really good for you say you know what i've tried in the past. It didn't work i tried to pass it didn't work try it again you never know you know so now i can actually now i can actually solve this thing. Yeah.

It only took it only took 40 years right i could i can solve it too. I do it very easily you just keep pulling the stickers off and putting them on the other side this right here on myself was actually the first rubik's cube. I ever solved and and if you notice. It's all messed up again so um one of my nieces came over and she decided to play with it and i kind of freaked out so so now now one of my past times is people build chips and bottles so if you notice that rubik's cube is in a bottle.

I actually build rubik's cubes and bottles. Now okay. That looks kind of neat right yeah i'd love to see how you accomplish and i put it back in the bottle. The same way that my niece left it so that is actually the first rubik's cube.

I saw. But it doesn't look solid. Now yeah well at least it shows that you're a good uncle yeah. But you know this this whole pressure enthalpy thing.

It's in my blood like i said i've been doing it since the mid 80s. So it's something that i absolutely absolutely love and uh and i'm glad my student has pushed me to to write the book on it yeah. We always need that extra that extra push um. So for people who want to they want to learn more about pressure enthalpy.

They want to learn how to plot things on the chart. They want to you know they want to get the book they want to expand how do they go about doing that well the book's available through through esco so they can visit um esko group e s c. O g. R o.

U. P. Dot org. And you know they have our e learning site in there we have you could shop you could you could buy the book there um.

You can get it on a number of platforms. Too you can get a hard copy. I this kind of book. You know i i recommend actually getting a physical copy of it so you can scribble in it and take notes you know so i mean it's available on you know kindle a lot of you know digital versions and and those are really really good but this book and pressure and psychometrics without tears.

It's the kind of book you want to sit down with with a red pen and post. It notes and those little sticky arrow. Things and and the way you get good at it is really just to go out there. And do it you know and you know my contact information is in the books too so i mean i do answer my emails.

I answer my phone when it when uh when i can. But yeah i know people have questions even in the big book in the refrigeration air conditioning technology. Title book. You know our contact information is in there.

You know so you're not alone so. When you know if you're out there with problems. We you know we definitely like to you know to help you out you know right now. It's about helping the future of this industry.

Yeah so if you want to you know call eugene on his cell phone at 3am on a sunday. He would love to hear from you about that it's happened. It's happened. I'm sure i'm sure i'm sure no i've got my copy right here on my desk.

Uh and it is great it's got the um. It's the demystification series. It's got the spiral bound. Which i really like because it's easy to flip open to a page and um at least.

I'm hoping it's still spiral bound. That's what my copy is like but i've had it for years. Yeah that book yeah i don't need to interrupt you. But that book and the psychometrics book even right like i said right now they're published by by esco.

But in the earlier years of those books. You know they were self published. And even then they were spiral bound. Because that's the kind of book that you need to open and have it be able to lay flat on the table as you're trying to plot one of these systems out and originally when i had them printed.

They weren't spiral bound. So you would open it up and you would let it go and it would close and it would so so we kind of went to the you know to the spiral binding. It just it makes it a lot easier. It's it's user friendly.

But yeah so you know with the chart. It's really about interpreting the shape you know overcharges under charges you know airflow problems. But uh. It's kind of neat and if nothing else it really helps solidify your understanding of the system.

As you mentioned before it's almost like being a hvac palm reader you know you just read the lines. Awesome all right well as always. Eugene it's a. Pleasure and i encourage everybody to go to escogrouporg.

Get the hard copy of the book. And as we've mentioned on many occasions here on the podcast and in the videos that if you go to the e learning site use the uh use our special coupon code. Which is all of a sudden i forgot what it is what is it hvac school. 22 that's what it is hvac school 22 to get a great discount um eugene thank you so much as always i appreciate you man be well me too thanks for watching our video.

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