In this video, Jim Jansen from Sporland talks about demystifying the TXV or the thermostatic expansion valve. Really enjoyed this class. Uh, really appreciative to Jim and to Sportland for coming to the 2023 Hvacr Symposium Here in Claremont Florida and teaching this class, there was many speaker sponsors who committed their time to teach these classes and to share their knowledge. You can still find all of the classes at the Virtual Ticket by going to Hvacrschool.com Symposium So here you go: Jim Jansen Talking about demystifying the thermostatic expansion valve.

Thank you! We're going to talk about thermostatic expansion valves today. Sporlins paying the tab for me to come here today. but I really thank this whole group for putting on this. Symposium This is really a nice thing I Mean they're going to feed you.

You've got drinks. It's a nice environment. it's this is the best I Don't know. Flea market Carnival Act I've been to in a long time.

They really do a nice job. Sporland makes a lot of different products for use in this industry. If you're familiar with us, you know we make everything from expansion valves to contaminant controls. And we do have a booth out here where we're talking about our press fittings for those of you who are interested and learn more about that.

So we do have a booth, please come by and see us! I'm Jim Jansen that's that's me right there. Uh, the guy on the left I'm uh what do they call me senior application engineer? That means I've been with the company a long time and I got a lot of gray hair. Uh I Started in this business family business. dad had been in a Ammonia Refrigeration mechanic.

You remember ammonia natural refrigerant never went away. still being used today. I Started a carrier dealership like this dealership here and worked there after school and during the Summers You know, summer break. Dad's idea of summer vacation was doing anything that you didn't normally do.

So he owned a farm too. so we're gonna go on vacation this weekend. Well, that meant you're going to haul hay or clean. Stables that was vacation.

but I also have John Woodhouse up here. That's just this guy right here. I've got him. He's usually my partner when we do webinars.

we kind of double team it. He's the extra smart guy, published, author, consultant, all that kind of stuff. and I'm kind of the. he's the straight guy and I'm the other guy.

How many of you know what the four main components are in a vapor compression refrigeration cycle? Raise your hand. Come on. What are they? We've got them up here. There's they're they're circled in fact for you got to have a compressor right there.

and we've got two heat transfer surfaces. You're you're trying to get heat to transfer from an area that you want a cooler refrigerate and then you want to reject it somewhere where you don't care if it exists and you also need some type of expansion device to go along with it. This is a multiplex system. Looks complicated, doesn't it? Does it look complicated? It looks it.

But if you think about it, you can count them. There's like five evaporators detailed here. When was the last time you went into a convenience store? a grocery store? any kind of supermarket? and they only had five display cases? So this is quite simple. though it looks very complicated if you remember that there's four main components.

five if you count the refrigerant tubing. six. Maybe if you include the refrigerant that's circulating through it, but there's just a few main components in every. Vapor compression system has to have those man words.

Stan Come on, they've got an extra seat up front if anybody wants it. I will only Heckle you. marginally. Now we kind of zoom in.

You'll see the evaporator detailed. You'll see a distributor that's feeding the multi multiple circuits that are feeding the evaporator. Then you'll see the expansion device. Bless you You doing okay there.

You don't have Covd or anything like that, do you? no? Okay, all right, we're going to detail and talk about thermostatic expansion valves and how they operate the some of the different types. I'm not promoting any manufacturer's valve, but they all work more or less the same. We're also going to talk about a an Associated device that works in conjunction with it, known as a distributor. Now here's kind of a cutaway of a typical sporland valve that we used to use in a lot of our ads.

and you can see here different components. There's the sensing bulb, a capillary tube that joins it to a thermostatic element assembly. you might hear this referred to as a power head in the industry. Then there's some attachment device to the body of the valve, and this particular valve has a lateral Inlet on the side of the valve and then an outlet.

And we believe it or not, even though there's an elbow Inlet on this valve, we call that straight through Construction You don't want us designing roads for sure, but it straight through. As far as thermostatic expansion valves are concerned. And this one happens to have a removable strainer assembly. The single biggest impediment to our products working well in a system.

You want to guess what that is. Contamination? Well, you part of it. Yeah, I Mean that's so. Things like this removable strainer assembly help to curtail that.

This will catch the hammer Handles in the lunch boxes, so to speak. Then we've got an adjustment assembly. You'll find that on a valve that is externally adjustable. Many of the valves you're going to encounter are not.

Now here's when I First got into the industry. it didn't make any sense to me that we referred to the capacity of the system in terms of a unit of measure that I equated to weight tons. How did we come up with that? I'm going to tell you how we came up with but one thing that happened. this was my partner who was calling on a military base.

the officer's mess tent. Not mess tent, but the officer's mess. The rooftop unit quit over a weekend. So they they and they and whoever was diagnosing the system knew what they were doing.

and they had a failure on the expansion valve. Rare as it is. Uh, I think they had snapped the cap tube and lost all the magic juice out of it. That's kind of like an electrical system frying and you lose all the magic smoke.

you can't put it back in. So they needed a replacement valve. So they called a parts house. Some guy went down there to open up on a weekend and and they needed a five ton valve.

Now they wouldn't let the technician drive down there to get it. Somebody from the motor pool had to go because that was the rules. So they tell the guy to motor pool. we got a five ton valve down to Parts House You got to go get it.

They send a flatbud truck. they did and they pull in down there. and so it's The old Question is, how much does a five ton valve weigh? Well, about two and a half pounds if it's still in a box. So he hands the parts.

he goes. What the hell. So why did that come about? Well before we had mechanical Vapor compression to get some type of refrigerating effect. The use of ice was very common, but they couldn't make ice.

They had to harvest it from streams, ponds Lakes bodies of water that froze over in the cold months of the year. and you see over here there's a delivery service for that. Oh wow, Wow. Holy smoke.

Olas Delivery of ice. You ever seen Ice and fuel? You know this company. ice and Fuel. Well, that's because they delivered ice.

You had somebody that would come along and deliver ice to you and put it in the ice box. How many of you refer to you? The fridge in the kitchen is an ice box. Basically where Yeti got the idea and still done to this day. Now the cooling effect that was delivered by melting a certain amount of ice over a certain period of time gave way to this concept of equating unit capacity to weight.

So a one ton block of ice either to freeze it or to thaw, it is equivalent to a number that you all probably know the 12 000 BTUs per hour conversion factor and that BTUs is British thermal units and the British get credit for that because there was British thermodynamicists that were working on that concept at the time and that's how this is equated. How many of you knew that before you came in here today? but some of you didn't, so maybe you learned that. if nothing else. Now, this is the this is really the demystifying part right? here.

We've cut away all the ancillary things involved with a thermostatic expansion valve. Now, some of you may know the that t EV as a TXV and you know the difference between the two. well. one in one case people know how to spell and the other one they don't.

Uh, I'm being I'm being sarcastic there. The the X valve part of it I think came out you'd see pressure piping an instrument diagrams sometimes and and how are valves often depicted. You'll see an X with a circumscribed circle around it and I think you know you know thermostatic in nature X and I think it was a very, you know natural inclination to call that a TXV So they're the same thing intended to convey the same concept. Now here's the demystifying part.

We've cut away all the ancillary bits and pieces and all. We have left: a sensing bulb, a capillary tube. There is a diaphragm, wafer, thin stainless steel, two push rods in this particular design, a pin working in conjunction with a port, a closing spring, and I always call it the closing spring because that for me, because again, I'm not very smart helps me remember what it's supposed to do. Closing spring: The bulb with its magic constituents will develop pressure in it when it's attached properly to the suction line, and it will provide a force that will cause this diaphragm to deflect, applying some movement to the push rods, which will then Force the pin away from the port so the bulb tries to open the valve.

the spring does what it close, closes, and then I'm typically also sampling evaporator pressure which I'm shown here someplace either in close proximity to the valve which would be generally referred to as it internally equalized valve though we're not really doing any equalizing and I'll explain that more, or in some from some remote location. but that's part of the feedback loop. so there's only three things telling the valve: What to do, a bulb that tries to open it, equalizer pressure that tries to close it, and a spring that tries to close it, and it's just that simple. And what's the result? The function of a thermostatic expansion valve in a vapor compression cycle.

Whether it's a Danfoss valve, a Sandwa name, fill in the blank Fujikoki, spoiling whoever is to control super heat which we'll talk about with superheat wherever you've mounted that bulb. and that's it and folks. And I made the mistake two years ago when I didn't know any better. They will adjust that valve to get suction pressure, to get amp, drawn, the compressor to get box temperature, and and you can get that done.

but then it won't do the job it was supposed to do and the whole thing won't work right. So if you remember nothing else from today, you know besides my name, you know Jim Jansen If you remember that a thermostatic expansion valve's job is to control superheat where that bulbs located into three things that tell it what to do or bulb bulb pressure or Force open it evaporator pressure or equalizer pressure trying to close it and spring pressure trying to close it and almost everybody's design has a closing spring whether they put it in the bowels of the valve or they put it up a top and this really helps to demystify this whole thing from my perspective. And if you hadn't ever seen this this is this is good to see. And when you adjust the valve, you're adding or subtracting preload from this spring.

so you're not changing the capacity of the valve. The things that impact the capacity of the valve are the diameter of that Port angle of the pin and the length of the push rods. Those are architectural features that you can't easily change out in the field, but you can change preload on that closing spring. but people think that changes its capacity, that just changes the superheat that you need to open the valve or allow it to go closed.

Does that make sense? Now there's a concept known as a bleed port and folks get confused about that. so we've tried to pull Concepts that our tech support people get asked all the time and we actually have humans that answer the phone who are in United States who will help you with questions if you call and they get asked about this. So what's a bleed port? We've exaggerated an opening that's been drilled or machined into the body of the valve and that just allows Inlet high side pressure to get to the low side of the system and bypass the regulation portion of the valve. So it's unregulated flow.

Why would you do that? heat heat pump? Maybe, but you would do that sometimes. If you've got a small system and you got low starting torque in the compressor and you have a valve that shuts off tightly and the high and the low sides don't equalize, it trips off and it won't start. It's a Hard Start kits how how many have heard of hard start kids? So this quickly allows the high and the low sides to equalize on an off cycle on our off cycle. Now it it doesn't have that in its name.

You know it doesn't say anything about Equalization it says bleed Port So people get confused by that. it's a bleed Port High inside low side Equalization off cycle or it's unregulated flow. That happens all the time. which means there's a little more capacity in the valve because it's you've added.

you've added area or volume if you will to the port opening. Except this happens all the time and normally what we do in our industry is we'll say well, it's 10 or 15, or 20, or 30, whatever the case may be and that adds to the overall capacity of the valve. You have to be able to live with that. And simply put, if you want to visualize it this way, you could approximate a bleed Port by adding an external piece of capillary tube tubing from the to bypass the whole valve.

That's basically what we're doing. and in fact, we tell folks if they encounter a project A system that has a valve with a large bleed port on it and and it has ceased to function because primarily because of contamination in the valve or because that cap tube might have snapped because of wear and tear. and the only thing they have is a replacement is a standard valve that they can get from a wholesaler with no bleed. Port We tell them you can.

You can size an appropriate piece of cap tubing and install it from the inlet to the outlet and approximate that. Does that make sense I mean that kind of shortcuts and gets it done. What you don't want to do is take a valve that has a bleed Port from the manufacturer and replace it with one that doesn't because there's probably a reason why they did have that either because of the off cycle pressure Equalization Are they needed that fine tuning with the extra capacity? Now this here's a definition of superheat. So in this case, we've Illustrated an evaporator with a little bit of instrumentation on it.

You see, we've got we've got a gauge that's reading pressure and then we've got an instrument that's reading surface temperature, the suction line and we're making the approximation that the surface temperature of the suction line and the temperature of the refrigerant flowing through it are the same Fair approximation. And we're saying that's the actual physical temperature of the refrigerant. If you measure the pressure you can then subsequently go to. we're depicting a pressure temperature chart over here on the left side.

You can pull up the saturation temperature that's associated with the pressure and that's a number and it's almost always going to be less than the measured surface temperature of that suction line. The difference between them is what we call superheat. It's a differential it it is kind of identifying the the the spacing between the actual conditions you you have in the system and what occurs at the saturation point which at the saturation point. then you start experiencing a certain amount of liquid being present.

and the the objective here is to make the best use of the evaporator. you know, fill it with refrigerant but not have so much in it that we send liquid back to the compressor and so that expansion valve in that role is acting as something of an insurance policy to help make sure that we get the best use out of the evaporator while not flooding or slugging the compressor and also not barbecuing. Oh, and by the way, we give these pressure temperature charts away and and you can download this this analysis guideline from our website for Free Continuous Flood Back. If things aren't set up properly, you can see wear patterns on these are some old Pistons out of a reciprocating compressor, you can see some wear lines on the Pistons Continuous flood back won't necessarily break things immediately, but it sure won't do them any good, whereas a nice big heavy slug of refrigerant going back to the compressor depending on the compressor type can cause some major failure.

You can see there's some parts that have, as my old dad used to say, come from together because they're not together anymore and there were supposed to be compressors don't like to. Oftentimes hear people in the industry refer to the compressor as a pump. Technically, it's not a pump, but I Get the vernacular. Pumps handle liquid nicely.

Compressors, not so much. Now here's some more demystifying Concepts Here we're talking about internally and externally equalized valves, and here's where people will think. Well, we're talking about the high and low side pressures equal to Isaac. No, not at all.

not at all. So it's a misnomer, but it's been in the industry on our part of the business forever. Internally equalized simply means that we're sampling evaporator pressure generally at the outlet. fitting of the expansion device right there.

Externally equalized means we've got a third fitting on the valve, which would provide for an equalization line that will place appropriately on the suction line again to sample low side pressure. Now, if you sample the pressure where you're trying to control superheat, it's going to do a better job. Some systems are designed to operate with internally equalized valves like this one, and that's fine, and you can almost always replace one of these with one of these, but not vice versa. But there's a caveat to that which I'll explain a little later.

If the valves roll is to control superheat where you place the bulb, wouldn't it follow that? Where you're placing the bulb comes into play and that's important. Wouldn't that make sense? So we're giving you some guidelines here that are in general they apply to anybody's valve. Generally speaking. if you mount it on the four or eight o'clock position, nine or three works pretty good too.

On the suction line that would be horizontal and free draining. they'll tend to work reasonably well. and here you can see that we're also talking about The Equalizer location on an externally equalized valve and we're tapping that in to the suction line here. and we're showing it tapping into the top of the suction line Downstream of the boat.

Now, why would those two things be important, Anybody? Yes, Yes, you got a question. Well, I would be so bold to say our valves never leak. except when they leak. and then and then if you've got them in this position, that leakage that might come through the equalizer causes the damn thing to close.

And and that happens every once in a while. So you don't want that. If however you organize it like this, you got a better chance. Everything working nicely.

Plus, you'll provide an Avenue for that equalizer line, which oftentimes are either eighth inch tubing or quarter inch tubing to not get contaminated with that single biggest culprit That keeps these things from working properly. Any kind of contamination. Here's some more guidelines on how to mount it. We got a free draining horizontal line prior to a trap if you got a riser and then you wouldn't believe it.

But people will use friction tape, duct tape, zip ties, you name it to attach Scentsy bulbs to suction line. Also, if that's convenient spot there where there's a where there's a a joint, they'll put it there. If you can see daylight between the bulb and the suction line, it's probably not going to work very well. and I see that all the time I Don't want to see daylight there.

Here's one more thing that's not widely known. You can use our I mean if you're familiar with Sporland valves, you know that we provide perforated brass knuckle slicers for you to use to attach the sensing bulb to the suction line. And they are good at that. but they're also good at being flexible enough for you to attach the bulb to varying sizes the suction lines and you can get them tight without crushing the bulb.

However, if you organize the bulb, the suction line, and the Fastener like we've shown here, you can make this tight and you can even crush the sensing bulb, but the thing will be loose up against the suction line so this makes a better way. We don't widely advertise that now. I've argued that that needs to be in our installation instructions, so maybe I'll get that done. Another concept that's confusing to folks: Conventional construction Balance: Port Construction What's what's a balance? Port Valve You balance the port I Thought the port was just an opening through the body of the valve.

How the hell you balance the port? It's more of a balancing the forces that are telling the valve what to do. Conventional designs are like that cutaway. I Showed you with two push rods in a pin and a port and that again, you just have the three main things telling the valve what to do. In this particular case, we're trying to eliminate a fourth influencing Force the inlet pressure if it's high enough, and the internal construction of the valve have large enough spaces, that condenser pressure can have an influencing effect on trying to drive the valve open.

So it's you know, a fourth thing telling the valve what to do and it's sort of like I've got a really off-color joke that I sometimes tell about this. you only want three things. Telling the valve What to do? Knock four and if we balance the port, we we can balance and there's several different ways we can do it. We can.

We can eliminate or neutralize that Inlet pressure. This depicts one. We've machined a a shoulder onto the push rod that's roughly equal to the exposed surface area of the pin that that in the pressure sees. So you have some Force pushing up and some Force pushing down on that push rod.

Here's an industrial size valve. We've made these for years. In fact, we still do. There's two ports in this valve.

There's two seat discs in this valve. One is forced up while the other is forced down. If they were exactly the same size, You Could argue that it was balanced perfectly, but because of the way we build the thing, we can't get all the parts together if we do it that way. So we refer to this as being semi-balanced and we still build this today.

and they're fairly widely distributed in large industrial applications. They're being replaced as time goes by by electrically actuated electronically controlled valves, and you're going to see more of those all the time. Now here's one that we build that is as good a balanced valve as I Know that we make it has a passageway drilled through the Piston assembly which acts as the pin and this one allows Inlet pressure to get to the underside of that whole mechanism such that there's Inlet pressure at the inlet and there's Inlet pressure down here at the closing spring location and that becomes as balanced the valve as we can make. Now those are a little pricier for us to manufacture and we still build these and sell them.

Large air conditioning Oems you know, carriers and trains still buy this type of valve from us. this is. this is typified of that first one that I showed to you where we've machined the push rod. And there's the push rod we've got.

Um, we've machined a shoulder on it so that we got Inlet pressure pushing up and then the pressure pushing down. And depending on how good a job we do, it's balanced or it's semi-balanced But a lot of our valves are made with this type of construction on valves that are equipped with an adjustment assembly. We can add or or subtract preload from that closing spring. Remember that closing spring.

Now, Typically what you would need to do is remove what we call the seal cap and that is the final seal in valves constructed This way, if you don't put it back on, the damn thing's going to leak at some point. Many of these valves have a packing gland around the adjustment assembly. We give away a tool for you to use to loosen that. Then you would make adjustments incremental small ones.

We say quarter turn. Let the system. It's not a light switch. Let the system run 15 20 minutes, check the conditions before you adjust it any further.

Typically people will go through the full range of adjustment that's built into the valve and then the back and forth and they never get the system time to settle down. and they're like this isn't working well, it's not working because you haven't given it a chance to settle down. It's not a light switch and I know times money. So this becomes frustrating as heck to get this done.

But once you're done adjusting it and you've got viable, constant superheat that's within specification of whatever the manufacturer said it ought to be, you'd re-tighten that packing gland and you'd replace the seal cap. How many degrees? That's hard to predict we are working on I Got a slide if I can make it to it without running out of time. that gives an uh, a recommended range of superheat for an application. and we are working on a superheat predictor that we've got on one of our software systems.

I'm not supposed to mention that and we're going to try to make an estimate of just exactly that. at this point. systems vary so much because you're building the system, you're You've got different length tubing, you've got all kinds of variables, and for us to predict operating superheat based on how many terms of adjustment you're going to make on an expansion valve is extremely difficult, but we're trying to work out to get to a point where if we say with these constraints, you can make the prediction, but we're not there yet. Yes sir.

Uh, I've heard a few times about Minimum Stable Superheat. Well, there is. There is what's called Static Superheat and that's what. Uh, you know the Ahri and Ashrae as far as what cracks the valve open and that's where we set the bowel when we're building it.

Every single valve that we make, we put on a test fixture. We have dry compressed air flowing through it. We control the bulb temperature and the inlet pressure and we we measure the outlet pressure and that correlates back to a static superheat. Then there's then there's uh, the you know the overall operating superheat.

We've got a nice bulletin called 10-9 that goes into almost Ad Nauseam. You can download it for free and I'd recommend that you do and then it and it goes into that. The minimum stable superheat depends on how low it evaporator temperature you have. The design of the system.

Is it air? conditioning? Is it refrigeration? The air conditioning guys tend to run a little higher superheat. The refrigeration applications can take a little lower depending on on the temperature and that's it. It's all over the board. Here's some of those recommendations: Application Air Conditioning you'll typically see I mean we've seen Oems take evaporator temperature up to 52 degrees already, which seems incredibly High to me.

Uh, air conditioning may be down as low as 40. And you could have a range of superheats anywhere from 8 to 12 and be perfectly acceptable in that application. Refer to what the manufacturer generally says and if they don't have a recommendation, here's some recommendations for you: You get into Commercial Refrigeration which might be 40 degrees and this says zero, but I'd say Commercial Refrigeration could go as low as as minus 10, maybe even minus 20. And these are all correlated back to thermostatic charges that we have available.

This would be correlated back to an air conditioning specific thermostatic charge. This would be a medium temp charge, and then this would be a low temp charge. We don't see a lot of minus 40 applications so much anymore, but there still are some, but these are from past history. Some rough guidelines that we've compiled unless the manufacturer has some proclivities to the contrary.

Here is a chart that shows superheat profile super heat plotted versus evaporator temperature, and you can see there's a wide variety of them where you'll see one up here called a sea charge right here. That is probably the closest thing that we have to I Hate the term wide range charge, but it's kind of a wide range charge and depending on the application, you can handle evaporator conditions in refrigeration as high as almost 50 degrees and go as low as minus 20. unsaturated suction temperature. but it's something you gotta.

you gotta if you're not in The Sweet Spot You kind of got to experiment with it to see if it works for you. But this is taken. the concept of there's not just one charge that works for everything You know. It varies by refrigerant that's in the system.

It varies by application. That's where something like an electronically controlled, electrically actuated valve has some Superior characteristics because it doesn't care about that as much. Now, this shows some depictions of two different adjustment mechanisms that we still manufacture. One is a rising stem.

One is a non-rising stem on the rising stem. The adjustment assembly has that packing gland around it that I talked about to keep it from leaking and if you look at it, you can get a visual determination of maybe how much that valve's been adjusted. You know if if the stems run all the way up into the valve, you know what somebody's done to it. If it's sticking, clear out and in fact, this one you get on it with a crescent wrench, you can run that.

Some of you can run that stem all the way out. This one has a follower that runs up a threaded rod and you have no such indications on it and this is becoming more the norm over here. On the right, We've made non-adjustable valves for air conditioning manufacturers for a long time. They want that because one, there's fewer Parts in it.

They want it because it allows or doesn't allow adjustment in the field and they know better than everybody. So they don't want technicians screwing with it and that works in certain types of systems. Certain types of systems. It's not so friendly.

These two valves are the same, except when you get down below the pin in the port and we can convert non-adjustable valves. For the most part, the valves that are adjustable. we sell kits to do that, and where manufacturers have insisted sometimes on a non-adjustable valve. We've run into situations where the poor technician out there trying to get everything to work right needs this and they can convert it.

We'll sell this adjustment, bottom cap, and and all of this, and then you throw away or discard the bottom portion troubleshooting. There's some things that can go wrong: Valves can starve, They can overfeed, or they can hunt, and that's not taking a gun out and shooting rabbits. it's just that's excessive modulation. Starving is high superheat and low suction pressure over feeds low superheat and high suction pressure.

Here are some causes for the high superheat: low suction pressure and you'll see in that list is contamination. A whole lot of things in there I'd go into great detail if I had time, but I'm going to move through this a little quickly and get as far as I can. Here's some more detail on that as far as migration is concerned, and that's the charge constituents not staying in the bulb where they need to be. This is something that we found Works to help us with that.

If it does occur, we can attach the the capillary tube to the suction line. Dead elements can occur that magic juice that we install them can escape. If that cap tube breaks, or we unavoidably manufacture one with a little pinhole leak in it, you can't put it back in, you've got to replace it. That'll keep the valve from opening.

then. low superheat. High Suction pressure means we've put too much refrigerant into that evaporator. Again, contamination is on that list, but there's a whole lot of other things on it as well.

TV Hunts excessive modulation. Now, what's excessive modulation? What's excessive to one person is not to another. But if the load is low, if the valve's oversized or you have other issues in the system, you can have wild swings in the super heat. There may not be a thing wrong with the expansion valve, but there's something wrong with how it's set up wide.

Distributors Well, that's because we got two phase flow flowing. After the refrigerant flows through the expansion valve, there's liquid and vapor and the distributor helps to manage that. If you you can get away with a header and there's many headers in a big refrigeration system. I Put single phase flow.

If it's two phase flow, we need a way to mix those two flow streams in appropriately sized distributor does that. and that's what we're depicting here. And if there is a distributor in the system and this is real important, an externally equalized valve is mandatory because of that extra pressure drop from the distributor. externally equalized valve is mandatory if that's the case.

And this gives an example. Why if you have excessive pressure drop in the evaporator because of a distributor being present and you're using an internally equalized valve, it's sampling Outlet pressure to help close it which will be too high if I sample it over by the bulb which is where I want it to be done anyway. you get a more accurate response and you can always substitute an externally equalized valve for an internal one, even if the internal one was the right choice for the system if you simply go ahead and run this equalizer line and attach it. So Size Matters We put a lot of design into these.

we've got them modeled in our virtual Engineer software and contamination again is a single biggest cause of problems in our systems. And I'm going to talk about contamination control tomorrow, so please come and join us. And there was a time where you had to specify all these different things when you bought a thermostatic expansion valve from us because we didn't have item numbers in the system, because we didn't have computers that could handle it. and to this day we still use all these descriptive features to pinpoint it.

At one point, if we're talking about a OEM designing a half or one ton R22 system, we had over 20 different versions of expansion valves that could handle that job. almost a bit too many. Now we've got a lot of teaching material you can get from Us online. it's free, We've got tech support you can call and get humans that have been in the business a long time will answer questions for you.

try not to ask stupid ones like what's Jansen's phone number at home or hey, we got tech support email sometimes I'm the one answering those and you can go online to access our our free software package, our YouTube channel all our free teaching material and we're happy to talk to you on the phone if you call us again. Big thanks to Jim Big thanks to Sportland All the sponsors measure Quick Akka for making the event possible. We are going to have another one next year so just keep an eye out at the Hvacrschool.com website for details on that and if you want to watch all the sessions, just go to Hvacartschool.com Symposium and you can still get the virtual pass to watch all of the sessions from this year's symposium. Thanks for watching our video if you enjoyed it and got something out of it.

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