Latest / The Refrigeration Mentor Podcast / Episode 358. Trend Graphs and CO2 System Troubleshooting with Andrew Freeburg and Erik Holland

Transcript

Episode 358. Trend Graphs and CO2 System Troubleshooting with Andrew Freeburg and Erik Holland · The Refrigeration Mentor Podcast

• 0:01
  Where this is something that you can do on an E two. 'cause Microthermal is super easy. Like you just pick a bunch of them and then you have like four or five graphs all at once. ? You can match them up. Where if you had Ultra Site it was easy to do, kind of easy to do with Ultra Site, but it's not, it's not difficult to do it with E two either.
• 0:02
  Speaker: Yeah. Which is good. This is something that you've been looking for for a long time now. It's not like this just happened overnight. You worked really hard towards this. You asked for it and they were like, ah, well we don't have anything yet.
• 0:03
  Speaker: Yeah, that's okay. How, what's been going on with in your beautiful life?
• 0:04
  And Andrew, do you wanna walk through the steps on that? On if someone's going to go up to a E two and pull up a trend graph, just even, yeah. Not even a double one, just a single trend graph. How do you actually do that?
• 0:05
  Speaker: like ALT I or alt o your inputs or ops against Alt I, you can go right to, to the point right there and then you go into that point and then graph it. The next step is how do you graph two points? That's the, the next step, right? So here's an example of an HPV valve. So a high pressure valve on a CO2 system.
• 0:06
  That doesn't seem right. It should, it should, , just be a real linear, I guess motion. But this one's just banging on and banging off. And that's what we're trying to do is control that. I mean, if we could control that in a better way we, we, the customer's gonna save a lot more money on energy and man, really less wear and tear on your.
• 0:07
  Like a, a fine smooth running system should be way tighter than that. And it doesn't mean that, it doesn't mean that it's the, the valve. PID set up. It doesn't mean that it's the val the valve itself. It may be something else in the system that is causing this erratic behavior. I think that's, that's something where I used to get stuck on.
• 0:08
  On a suction group. I mean, if that thing is all over the place, then all your valves are gonna be all over the place, and that means your temperatures are gonna be all over the place. So yeah, it, it all affects the system, so we have to, that's where that fine tuning commissioning comes into play. And that's where I'm really starting to spend a lot of my time now, is trying to make these graphs not look like, like, like what that graph looks like.
• 0:09
  This is, it's something that's not done enough and it's gonna, it is gonna, I see it done more now because there's more electronics. But when I was in there, like in the field 15, 20 years ago on the tools there, we, I'd never heard of continuous commissioning. It wasn't really a thing that was, was even a really a role that it, there was roles, don't get me wrong.
• 0:10
  Speaker 2: Oh yeah. I mean, just, just the ambient conditions alone, you got more valves that are going to maintain head pressure. I mean, not necessarily valves depending on where you're at in the world, but yeah, it's a whole different ballgame when you're talking about low AMIT conditions versus hot Amit conditions, ?
• 0:11
  Speaker 2: Yeah, I agree. And, and really what it comes down to if you, if this interests you, like you, like I've done, is say something. If, if you wanna learn what this is, say it talk to your boss and say, Hey, I would like to learn more about this, and they're gonna give the opportunity. Most likely it just gotta be, , set up, right.
• 0:12
  And now I'm trying to figure out how, , and that that's, that's what's fun about this trade. So.
• 0:13
  Speaker 2: Oh, for sure. Yeah, the e threes is, it makes it a lot easier, but it's a lot newer, so it kind of goes hand in hand, right? Yeah, yeah,
• 0:14
  Speaker 2: Mm-hmm. And so, yeah. But just go ahead, sir. Just seeing that like, I'm like, man, there's, we can do better. I mean, that, that to me just seems like that valve is just all over the place that's trying to maintain, which, which it is.
• 0:15
  ? Maybe you're working on, sometimes I, I work with a lot of contractors and technicians who work on supermarket rack, but they're also doing the air handlers or the heat pumps at the stores. ? Like, they're, they're working on everything. So they might be here, there for something else and they just wanna go check on the rack to see how it's running.
• 0:16
  'cause you never know. Actually, prime example this was great. I was on a HVAC call the dehumidification, I live right off the coast, so there's a lot of humidity over here. And it was making the, the glass door sweat all the time. So I went over there and find the, actually, I just went, they had a Dan Fos 800 series time controller for their HVAC and refrigeration.
• 0:17
  I was able to get the rack going a hundred percent, but that's just, , taking that extra step and that you just found some, some work of course, too, which I know it's not every situation, you have time to take care of extra work, but you just really saved that customer a lot of headache. Maybe, , if the, if the system went down overnight or whatever it may be, or you just saved your on-call guy, that on-call guy that just, , you just saved them from having to come out middle of the night now and you were able to handle it.
• 0:18
  They're not, they're usually not calling dispatch for work. They have enough work 'cause they know how to create work for themselves or, or what is not even creating work. It's just seeing the work that needs to be done and they're taking that down, noting it, that down and building their own like dispatch for themselves, their own service calls.
• 0:19
  Speaker 2: Yeah. Yeah, absolutely. Gr reading the graphs is, is a game changer once you spend the time to learn. What you're looking at in a graph, if, if you can figure that out, it, it makes diagnosing just that portion of it a lot better. Then you could also come into a store and see that there's obviously a problem.
• 0:20
  If you have worked on a, on an E three or microthermal Dan Foss 800 series, you, you could pull up multiple graphs at one time, which is super nice. But you, , the E two is kind of, , it's kind, it's dated. So when I found out that you could pull two graphs, man, I almost do that every time now because it just gives you that much more information to figure out what's going on.
• 0:21
  They're, they're running pretty good, but something happened right at this point right here. Something happened in the system now you got your pressure control valve going all the way up and right down to its minimum setting, whatever the minimum setting was at this one, opening it up, going right down to the minimum setting, opening it up, going right down to its minimum setting.
• 0:22
  So the, those are the two things that come to mind, but I honestly don't fully remember what I did to fix it. Obviously this was the something going on, then something happened. Maybe it was the VFD settings on the condenser fan. It's been too long for me to remember exactly what I did to fix it, but really the main thing here is like, okay, there's obviously something wrong, right?
• 0:23
  Speaker 3: This triggers me quite a lot. Yeah. And, and knowing these two valves here, how they, how they work and operate that is the, the fundamentals to be able to analyze what you're seeing.
• 0:24
  I think you should find your problem at, at the, at the, at the high pressure site somewhere. And my go-to guy as soon as we talking high pressure is my gas cooler. The gas cooler will be point number one to, to, to, to look at. If I can view here, share my screen here. I requested you.
• 0:25
  Speaker: ' cause that's, that's a a good point that you had there, Eric. , That's, that, that HPV opens up, then the flash gas needs to let some of that gas through. ? So that's trying to compensate. And then what, what you can get is fighting and like you said, I really like what you said, that high pressure valve, you see that, that acting app, it's something to do with the gas cooler.
• 0:26
  Speaker 3: Just a quick run through. So the first thing I'm gonna look at is figuring out what, how, how, how, what is controlling the high, our high pressure valve. And that is basically our, our ambient temperature. Because as mo I don't, I'm not quite sure with the, with the, with the E two system, but I'm reasonably sure that it's controlled by the ambient temperature is a set point for, for the, for the droplet temperature.
• 0:27
  So, so my go-to will definitely be check the gas coolers. It's running. Is anything blocking the, the, the, the heat exchangers in it? Is the sensors, are they okay, are they, are they exposed to, to, to sunlight or whatever, or, or a different heat source. So we get on a false readings and my, my pipe temperature sensor here, is that firmly connected to the pipe?
• 0:28
  Speaker 3: That could also cause that effect Because when, when you got, I think that's when you got instability in your gas cooler, then you have an have a fluctuating drop like temperature. Then your pressure set point will also be changing up and down and depending on how your system is working there, there, of course there will be some smoothing in, in this set point here calculation.
• 0:29
  Mm-hmm. Then your expansion valves here are trying to fight that because they're trying to feed in a, a metered amount of of liquid to, to maintain super heat. If you, if that liquid flow is constantly changing, it's constantly working to, to letting more, more liquid or less liquid. And then in turn then the final step will be your compressors will also start to oscillate, and then now you can see you're in a bad circle.
• 0:30
  Speaker: That, and that's something that is basic, ? That having a clean, clean con condenser gas cooler. So I wanna go back just a couple of things. So you said that the high pressure valve on the system here, the high pressure valve is controlled by the ambient sensor plus the gas cooler drop leg sensor of two three K.
• 0:31
  Speaker: Yeah, so that's important. So just so everyone's listening, 'cause a lot of people are listening on the, , afterwards it's the ambient sensor plus two or three K will trigger those fans to turn on and turn off or ramp up and ramp down. Because a lot of them are all, like, sometimes I see a bunch of them, and I don't know how you guys do it on all your systems, Eric, but like, if there's six fans, all six will ramp up at once and ramp down.
• 0:32
  Off, , down, they were downstairs and they were off. They checked with their volt meter, , check if they were getting a zero to 10 volt DC out to the gas cooler and there was no, there was no 'cause at zero it, it turns them all on, ? So fail safe, but it was at 10 Volts DC So realistically they should have been off.
• 0:33
  But but do, do your checks then, then you're good. So yeah, just to explain with, with numbers if for the listeners so if you've got an ambient temperature of let's say 20 degrees C what, whether that be, that would be 70, 75 ish Fahr?
• 0:34
  That would be your 60, 62 bars, something like that. Yeah. And if I'm, if I remember correctly, is that just about that? So 60, 62 bar, that would be your, your, your minimum condenser pressure at this time. So that's what, that's what the valve here would try to maintain. So we would always try to mm-hmm.
• 0:35
  What's your thoughts on that? How do you control it? What, what's your go-to, I guess, when you're starting to commissioning? What's the best way to handle that situation?
• 0:36
  Just set a manual speed of like 80% output or something like that. So you, so that is not affecting your signals now. Now you gotta a steady. Steady cooling of, of of, of your gas. So now the gas cooler is not an issue anymore. Then you can see what happens and, and you try work away from that.
• 0:37
  What that high pressure valve is doing, what affects that flash tank receiver pressure, which will affect the flash gas bypass valve, which will affect the EAVs, which then affect the suction, suction and oil pressure. ? Mm-hmm. So you may, you may come up and you have an oil issue, but the oil issue isn't necessarily because of the oil, , itself.
• 0:38
  So, so that, that's, that's the key route. If you've got unstable systems, then, then you need to obtain stability somehow to, to figure out what's going on. And, and everything starts at, at the gas cooler. So start with the gas cooler, either switch off the fans or sit them on full speed just to create some kind of stability and then work your way from, from that.
• 0:39
  ? Or Yeah. Degrees out. So it's just understanding where that equipment's gonna be placed and how is it set up and designed, which, when you're looking at your oil trend graph, that's gonna be a major di difference when you get, start to get oil liquid refrigerant in your receiver, oil
• 0:40
  Speaker 4: Yep.
• 0:41
  Speaker: Yeah. Mi yeah. So minus 10 Celsius. Just say that liquid would be about which is 14 degrees Fahrenheit is 369 PSI, or 25.5 bar, ? So that's, yeah. You
• 0:42
  Speaker 3: We've seen, yeah. Quite a lot actually, because there's more and more times we get into, especially bigger industrial installations where they only starting up parts of the system and then later on adding on more capacity.
• 0:43
  So you, so you add a little bit. I know for the Dan, for CCM T valves, which we are using here. It's, it's actually still closed, even if it's the, IT controller says like 5% output. So then the piston is still on the seal. But if you just move that minimum opening up to maybe seven or 10 ish in that neighborhood, you get just, just a crack open.
• 0:44
  From Hill Phoenix. And they, what they did, it was a, it was offline for a couple years and they used it at a different store, but the store was a different capacity and the low temp would just shut off. ? Like mm-hmm. And then when you're low temp shut off, it affects the medium temp and hot gas defrost and all this.
• 0:45
  Speaker 3: We had at some point we had a customer who always started up his low Tim rooms, his freezing rooms before his medium TIM rooms. Okay. Which caused a lot, a lot of issues in, in the startup procedure because now you, you need to make sure your, your MC group is actually working before you could start the LT room, but, but you cannot check if it's working because you don't have any load on the MC side.
• 0:46
  It's not just a ball valve, but it's a ball valve with a V-shaped cutout. So you have a line area opening degree and then, then you can, then you can tell the control system to look at your return temperature at the at the machine and say, okay, if you go below a certain temperature, I can start bypassing a bit of gas, a hot gas coming in here directly around the gas scooter.
• 0:47
  This was the time when I was there, ? Like, that's a big piece of metal that is really, really cold. ? So it doesn't even matter if the fans are off, , it doesn't matter if the fans are off, it's just Nope. The, the metal and the pipes are cold. So I've been seeing more and more of these bypass happening.
• 0:48
  Speaker 3: But it, it is, it is useful if you, if you, we use it a lot when you have heat recco heat recovery systems on when you have your, your big, big heat exchanger up, up here, and then you want.
• 0:49
  Speaker 2: So that's obviously a low ambient thing. So like, is there like a degree range where all of a sudden you're probably should consider this in your design that you've noticed, Eric?
• 0:50
  So it's more, it's more likely to be seen in, in, in the colder climate. I think California not too much. But I can see some application where it would be nice to have, especially if you are using the racks as a heat pump, then you basically wanna do this and only have a gas cooler as in more or less like an emergency cooler if you, if you are not unable to recover all the heat in your heat exchanges.
• 0:51
  Any any, any final thoughts? Andrew? For, let's start with, we'll go with the, the trend graphs, 'cause that's where we started and then we got to this conversation, which is really good, which takes us back to the trend graphs on how the system should actually work. 'cause I think that's the biggest thing.
• 0:52
  Or there's a problem taking the time looking at the graphs at multiple stores. Don't just do it one store. Go to all the stores that you have, pull the same, same, whatever that might be. Pull it up if it's a pressure, is the high pressure, and just start comparing them. And that is, that's honestly the best advice I could probably give you is just start looking at 'em and then and then that's when you're gonna start to see consistencies, as you go through and start looking at 'em, and then you're gonna, you're gonna see something that like, well, something happened here. It's weird. I don't understand what's going on. And that's where your curiosity kicks in, and that's where you go and investigate what's going on.
• 0:53
  Andrew does this because he, he knows the struggles that he went through. Same with me. I do this 'cause I know the struggles I went through, and we don't want you to go through as many of those struggles 'cause you don't, shouldn't have to. You shouldn't have to. I've had a post on LinkedIn that someone was about a gasket.
• 0:54
  ? And you always willing to learn because I didn't know. Even working at Copeland for so many years, nobody said that you don't oil the metal gasket. I train people to oil metal gasket where Bitzer says they don't want you to oil metal gasket. And I know people listening, they, they do it all the time.
• 0:55
  You've come on, like, I've had people message about the sessions that we've done before, and same with you, Andrew. I really appreciate you guys taking the time to, to share this knowledge with others.
• 0:56
  And so I, I like your point there. Sometimes you have to just sit and just look at it and watch it. I know me and Rusty Walker had quite a few conversations of if you want to see how a system really one runs, you sit on a bucket and you watch it, , that's it. ? And I've done that for a long time.