Latest / The Refrigeration Mentor Podcast / Episode 346. Troubleshooting CO2 Gas Coolers with Greg Martel and Al Rivera of BAC (Part 2 of 2)

Transcript

Episode 346. Troubleshooting CO2 Gas Coolers with Greg Martel and Al Rivera of BAC (Part 2 of 2) · The Refrigeration Mentor Podcast

• 0:00
  Speaker 5: Hey, welcome back everyone. So happy that you're here. This is gonna be part two of the session I did with Greg and Al from BAC, talking about their CO2 Atic gas. Cooler. This is once again, is what I talk about consistently in our CO2 training programs, the different training programs that we have. Really how do you set those things up?
• 0:01
  , Running into issues and we want to try to help you understand the, these systems a little bit more. Giving you some practical service tips. , For example, like how to properly remove and clean the pads we walk through on the do's and don'ts that checking out. What these common issues are, what are the common codes on the alarm boards in the systems?
• 0:02
  Speaker 3: So usually it's the most commons are related to the water system. So it would say it would be either pump failure. So pump failure means that the proof was not made. So the PLC sent out a DA digital output to turn the pump on. It did that, but it did not receive proof through the current.
• 0:03
  Speaker 3: Well, so let's say that we, we get that alarm and we're standing in front of the unit. So obviously the first thing will be to check that the pump is not running. Like, we'll touch the pads or see that there's no water. So there's no water. We have to assume that the pump is not running.
• 0:04
  Speaker: Okay. So, so that's great. So when we, so we're still on this call, you check the breakers tripped, you turn it on and it runs fine.
• 0:05
  But it is. So it turns out that we have a transformer in there, which is a linear device. So it, it would, if at two 30 you get one 20 or one 15, at 2 0 8, you're gonna get like 90. So your pump will run. But because of OMS law, now you're gonna be pulling significantly higher. So it would run maybe for a week a month, who knows, maybe even longer, depending how long.
• 0:06
  The PLC and the rest of the devices are really tolerant. To fluctuations in voltage. So like the PLC can take anything from like 36 to 20 volts ac. So even if you w incorrectly, you know those PLCs have a huge range. So they're same thing as the fans. The fans have a huge range. The fans can do four they can do 200 to two 30, so they don't really care.
• 0:07
  Well, essentially you've got a drain valve that's closed and you've got a makeup valve that's staying open. The unit's calling for water. The sums full, but it, but it doesn't, it doesn't know that, so. Could be a couple things. You could check the drain valve. Maybe the drain valve is commanded, is being commanded open, but it's, but it's stuck in the closed position.
• 0:08
  Speaker 3: So another code that we get, it's called make water failure slash no water in the system. Okay. So that is a literally an alarm that our unit gets and that, that one could be multiple things. So the first thing you should check is make sure that the pipe going to the unit has water.
• 0:09
  You get that alarm, but the unit is overflowing with water. So that just makes no sense. So what has happened is the only way the unit knows if there's water on the basin is with the float. So if the float is down and the makeup is open for 10 hours and the float never closes, the unit is gonna think that either there's no water in the building or that your makeup has failed.
• 0:10
  So when you apply water power to it, it opens. Now the drain valve is normally open, so if you're running the unit in wet mode, you expect it to be closed. So for it to close, it needs to have power. So sometimes we get calls saying, well, the unit is working backwards. Because I'm, I'm putting my meter on the drain valve.
• 0:11
  Is that correct? And when exactly, the pads not all of a sudden the temperature drops down to 65 Fahrenheit or down to 10, 12 Celsius. All of a sudden we don't need any water that's gonna be open, so we're drain it so there's no bacteria building up in the water or in the, the gas cooler. So Legionnaire disease and all that stuff.
• 0:12
  So if, if, if you lose all power, the unit should be dry. So a dry unit means a closed makeup valve and an open drain valve. I love that.
• 0:13
  Our unit PLC controls the waterside system, so the makeup valve, the drain valve, the float switch, and the pump, that's all handled by the onboard PLC. And then as far as an external control signal, we're, we're looking for the fan speed signal from the customer's rack controller. And typically that's a 10 to zero volt signal, so sending the unit 10 volts, the fans are off sending it zero volts.
• 0:14
  They'll be able to see many more points many more alarms, and then they can get into more nuanced control. They can command the pump on and off themself. They can see more of the, of the readable values and such. But I, I think we're probably moving more in that direction, but it's still a relatively small subset of customers that are taking that extra step and doing that full on controls integration.
• 0:15
  Everything is carere, like the sensor, the temperature sensor. It's, it's Carell obviously that, that our controller is really small. It, it basically just controls the water system. And then obviously the fans that have their own PLC in them.
• 0:16
  And I use Google Molecular weight of ammonia on the phone and that's how I know the password. So yeah, it's just a good way of remembering that and that that password is needed if you wanted to do like changes. Like the timers, if you wanted to change how often the unit dumps and things like that. And the other, the, the things that you guys were talking about before, how we control the unit.
• 0:17
  So that is something that you can easily change on the PLC. And, and the promise is that if you don't know that the unit is just gonna run at full speed forever because no signal, you know, the fans are designed to fail at full speed, so at least you have some cooling, but obviously you, you won't have control of the fans.
• 0:18
  ? If you want a good efficient running system, one of the big things is though, is seasonal efficiencies. And this is where I get, I have lots of conversations, well. Should the summertime set points be different than the wintertime set points and transitioning like to those high peaks, to those cold winter months.
• 0:19
  You know, it's, it's funny, we, we, we size these heat rejection devices based on design day. Everyone's worried about peak ambient conditions. I have customers using Ashray 10 year extreme conditions. But. Honestly, we have more issues with stable control during the colder months. We, I, I don't think we've ever had an issue meeting capacity in the summer.
• 0:20
  Speaker 3: Yeah, so like Al was saying sometimes our customers think that a bigger unit is better. More capacity, you know? But the problem is in the winter time, now the unit is sign, especially in places like that, gets really cold. Like Canada. Canada. Oh yeah, yeah.
• 0:21
  So it is important to take advantage of that because, you know, some of the cost of that fan, I mean, customers are paying for that technology, so I think they should use it. So tuning the PAE loop on a cold day, that's important. I know that startups are usually, or, or they could be there in the summer or things like that, but it's important to go back in the winter time and make sure that things are stable.
• 0:22
  Speaker 3: know, cycling like that. So I wouldn't say that there's no setting in our unit. There's nothing you need to do physically to our unit for any season, because it only cares about one thing, the outside air temperature, and it will turn the water on and off based on that.
• 0:23
  'cause I, I've seen this run into an issue like you just said earlier. The customer thinks a bigger gas cooler is better, but if I have eight fans, even at the minimum speed of 5%, that might be too much. What are can, can they separate them if they want? Or what is your thoughts on running that? 'cause this is a low ambient issue and I seen it on multiple gas coolers in different locations where that 5% is just still too much.
• 0:24
  Speaker 3: So yeah, it might help a little bit, but e efficiency wise, I mean, if you're looking at your power consumption, it's just not it, it, it is cheaper to run eight fans at 5% than to run two at 50%, or, I mean, the math is in there. Yeah.
• 0:25
  Is there any strategy before the fans, because we said a, a temperature of say 72, you know, the water comes on. Does the fans have to be at a hundred percent before that comes on, or is that a strategy up to the manufacturer, the contractor?
• 0:26
  One is called energy saver mode. And what that does is that it will, it will command the water on if your fan speed is over 35%, even if we haven't reached the ambient temperature set point. So basically it's gonna keep your fan speed at 35% and. Using water to save energy and run the, and run the fans more.
• 0:27
  It's yeah, it's, it's available for customers to use, but most people are just controlling the fan speed based on the control algorithm from their rack controller.
• 0:28
  Is, is is the facility manager staring at the water bill? Is he staring at the electric bill or is he looking at it from a, from a holistic standpoint? So yeah, you could also, you know, try one month to the next and see the results and you know compare if you're, if you're monitoring your energy and water use.
• 0:29
  Speaker 3: And obviously like I was saying, now you only run water if your fan speed is above 90% for over 10 seconds, 15 seconds, something like that. So that works. Awesome. And units that are slightly oversized, because as as, I mean, I know it's opposite to what I said before, but, but what happens is now if you have more dry capacity, obviously you can sustain your set points for longer.
• 0:30
  Speaker: subcritical. And then in the winter months, we don't want it to run too low, like you guys said. We've got that valve holdback valve and that comes play with the, with the gas cooler to make sure that our pressures, we don't get too low because if we get too low, then now we get oil issues and we got compressor issues, which you guys, you guys probably get called for, you know, it's like the gas cooler issue.
• 0:31
  So it was working fine for two years and now today it doesn't meet set point and my head pressures are through the roof. So we, we have a case, and again, we, we could spend hours talking about this. We had a case in Phoenix, Arizona. It was like 119 degrees outside. We got a call, the unit doesn't have capacity, but it had capacity months ago, but now, today it doesn't.
• 0:32
  The other thing that we have seen is that sometimes what I usually do when I show up on a site like this where the, the customer complains about lost capacity, I would just look at the gas, whatever gas it might be. It could be CO2 or anything. I would look at the pressure on the pipe and I'll look at the temperature and I will compare it to a chart to a CO2 chart or whatever gas.
• 0:33
  If you see the water just dropping off the pads and not going down the pads, that's an issue as well. So do you wanna talk about how to probably put them on and take them off maybe.
• 0:34
  Like the situation Greg mentioned, where the pad's upside down. You don't have that water distribution piece at the top that spreads the water over the pad and allows it to fully, to fully soak in. It's, it's, it's easy to see. It's like a separate like a separate piece of cardboard box that's at the top.
• 0:35
  So try to make that simple, but if you're not aware of the orifice plug even existing, it, it's easy to skip that step.
• 0:36
  And, and all that doesn't sound like a big deal. It sounds like. It doesn't, it makes a huge difference. I mean, you basically lose like 40, 50% of your capacity just by doing that. And we have seen it many times when, when the pads get installed up, dry
• 0:37
  So that's the best thing to do. Another thing is when you open the control panel, you can kill power to the low voltage to the controller PLC, all the 24 1 20 volts and leave power onto the fence. They will stay on at full speed. Forever, basically. So there's a way to do this without having to shut down the store or the rack, which is, which is just leave the fans running, you know, kill your low voltage, and now you're letting the fans dry off the pads, right?
• 0:38
  But do not install all of them because they're not gonna fit again, because they're too, too they have expanded. They're a little bit too wide still. And that will help accelerate the product because I, we, we usually tell people just to let them dry in the sun, but then technicians would say, well, then I'm gonna lose eight hours.
• 0:39
  Any, any final thoughts, any tips you'd like to give technicians, either new out there, or technicians who are gonna be cackling these gas coolers at some point? Any any final thoughts? Al?
• 0:40
  Speaker 3: No. Same thing that Al is saying and, and, and also, I would like to know also what, what, what technicians want to learn about what they want to know. I don't know. It probably happens to you, Trevor, a lot. Like sometimes we have groups of, of technicians who want to learn about, like thermodynamics and they wanna learn more about the science behind it.
• 0:41
  There's something happening in that gas cooler. Why, why do you design them this way? You know, you were part of the design team, Greg, ? So why did you design them in this way? So we can probably dive into that because I, I can give you some tips as well as people that ask me what they're looking for.
• 0:42
  Speaker: So that's, that's one step. And so if they need a call like for support, just say that they need some help. They go through all what we talked about today. They check the sensors, they check the faults, they check the pump. But the real, they're, they're really stuck.
• 0:43
  I really, really appreciate. So thank you guys very much.