Latest / The Refrigeration Mentor Podcast / Episode 350. Supermarket Refrigeration Tips and Tricks with Robert Ochs

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Episode 350. Supermarket Refrigeration Tips and Tricks with Robert Ochs · The Refrigeration Mentor Podcast

• 0:00
  Trevor: Welcome to the Refrigeration Mentor podcast. Super happy you're here. So this next podcast is recorded from the refrigeration mentor community@refrigerationmentor.com slash hub. Had my good friend Rob Oaks come out and started talking deep on supermarket refrigeration. Some tips and tricks that you know is gonna help me share and help other technicians that I didn't even consider.
• 0:01
  At the case versus the rack to make it run more efficiently and effectively. This is a super cool episode. Thanks for all the community members asking questions. And if you're interested in joining this community, head to refrigeration mentor.com/hub. We're there to help and grow technicians in the refrigeration space, level them up, get to the next level in their career, and as always, let's get a conversation going.
• 0:02
  Yep. Two compressors I didn't even know they had, you know, which was really cool. Now he is moved on to a new company. Congratulations. Thank you for much. And I out there and now we're gonna have a conversation about some rack refrigeration. So, When I first started to talk with Rob, he started to tell me about a little bit about his history and what he, what he knew about refrigeration.
• 0:03
  I'm, you know, I hate to see my phone number, my name out there with a, a, a piece of junk. Yeah.
• 0:04
  What's, yep. What's the difference of checking net oil pressure, rob, onto just a standard compressor versus a compound compressor and how do you do it?
• 0:05
  So all we did was add that manifold externally that you're seeing connecting head one and head two, right? Which become your four suction through the inner stage of the last two of your discharge. So the reason I should back up a little bit, the reason those were developed was for low temp R 22, but checking the net oil pressure on an oh six cc, right?
• 0:06
  You'll have your net oil pressure on your oil pump in the front. So although we have the little pressure sensor, we, we have a a port there on the high side of the pump. So you should get, I think it's about, I don't remember the book right now. I'm thinking nine pounds to 15 pounds is our standard net oil pressure on an but the oil pressures are exactly the same as the DE because of the exact same internals.
• 0:07
  What were what, because you've done it for a long time, you did all the designing. What were some of the biggest rack troubleshooting issues you've seen in your in your day? Because a lot of people, these are the biggest things that I get in my courses, Rob. Sure. I get oil issues. Is a big one.
• 0:08
  So I would say some of the key ones that I typically answer, we're just talking about parallel system racks. I just wanna start where you guys kind of started your, your conversation where we picked up on expansion valves. So I, I'm with you on the balance part and on the sticky part, but a lot of times and I just had this same circumstance 'cause there's a lot of old systems in the US out there, but I had the circumstance actually recently with Sprouts.
• 0:09
  So that's the gas on top of the receiver that they'll use. That is a tempered gas to do defrost versus straight hot gas that they felt in that engineering timeframe. Guys that would crack coils, crack copper, right? And so they were trying to get away with that. But in those differences, when you approach a parallel system rack from a nineties rack to a two thousands rack, and that's kind of where the break was in refrigeration, some of those that you'll get is that how do you choke that in order to get the gas to flow and defrost.
• 0:10
  So it's not a type of store that you wanna go in and say, you know what? My cases are icing up. I think you wanna get to root cause analysis. Like Trevor points out. You don't wanna say, look, I'm gonna add another 15 minutes to defrost. I'm gonna add another 20 minutes. That'll clear up my ice. Rather than finding the root cause of, Hey, I have a plugged drain, I have a dirty coil, I have a fans that are out.
• 0:11
  So it's very, very common that you go into a store with problematic tech after tech, after tech. But I just wanted, that's a big call because I have that a lot that, Hey, my store's not working. I just did this literally with Sprouts at FMI, you know, that Trevor and I were just recently at, they said, Hey, listen, my store's not running, blah, blah, blah.
• 0:12
  The second thing, I just wanna stay on the, the, the, the expansion valve on the balance port guys. So talking about super heat, I heard you guys talking about gumming up when I jumped on the call here. So a lot of times you gotta set that super heat. I wanna back up one step from an engineering standpoint.
• 0:13
  So it's very, very critical that you go in, 'cause a lot of stores don't wanna spend time or money to add, add the right level of gas. So now you have, you don't have the latent gas or the cool gas. They don't want to charge the system and let the technician put 20 or 30% in the receiver. So now you're coming up to a lack of sub cooling.
• 0:14
  So it's a different strategy. But what I want to go back to is talk about is that, so what you've seen is people increase the defrost times in a lot of the cases, and that's a major issue for cool gas defrost.
• 0:15
  So when it comes out of that cool gas or latent gas defrosts, whatever the terminology is, by the OEM manufacturer. Yeah. Now my velocity inside the pipe is so fast. My valves are hunting for I can never catch up. Because I have, I have consumers that are breaking the air, bands reaching in the cases I have air conditioning, and I live in Arizona, guys, so in Arizona I have air conditioning that the building's not at temperature.
• 0:16
  If you don't have those conditions in your store, because the store manager says, I wanna save energy and I run my store at 78 degrees or 79, your super heat is not going to be the same. So you read the book. When you read that book, and now you've got this velocity because you've choked this OLDR and you've starved the liquid.
• 0:17
  Trevor: We got a question here. How do you find the proper design subcool temperature of a system manual based on refrigerant py that comes from the manufacturer.
• 0:18
  Guest 3: Yeah. And a lot of times guys, at least when I did the schedules, you should see the as-built in the mechanical room. And you'll look for that liquid temp and the way that we typically design through the nineties into the two thousands, and I would say up to about 2015, the normal design for sub cooling just to give you guys a little hint in the event that you're, you're there and you lose a compressor.
• 0:19
  But if we're in states, like I live in again, Arizona, where I'm hot in the summer, we would go to both valves and get nine tons through that sub cooler. So there's a strategy on the sub cooler. So if you're not managing liquid temp, you're either short on gas or those valves, your super heat on your subcool isn't set.
• 0:20
  I can't get a car out compressor. It's down. The store doesn't have it. You know, I can't keep the store running. What do I do? I would say, okay, go over to the sub cooler, turn it down to 45 degrees. If I got colder liquid, I can offset that horsepower need and that CFM, because now my liquid quality is greater and I could do more work to survive that circumstance if I lost a five horse or a 10 in between the five and the 15.
• 0:21
  Within that health department, you know, requirement. Yeah. I don't know if people know that strategy or not, but we do design it like that.
• 0:22
  Yes. And it's in there. It'll say cool gas defrost. And it'll tell you the time. So you might have to go back and reset a whole store that's been butchered, not butchered, but really mis, mis tuned over the years. ? Yes. This is why fine tuning or going back and retuning a store, which I keep telling customers.
• 0:23
  And we could talk more about different strategies on these systems. I was like, oh, as soon as I walked up, I could see it from. Being an engineer and being a technician and having that background, oh, hey, whole Foods, you need to do this, this, and this. It wasn't, oh my gosh, they can, why didn't we do that five years ago?
• 0:24
  So we get the oil back to the system. Well. A lot of times you have to look as a technician. Do I have a 60 foot run to a parallel system rack? Do I have a 300 foot, like in Las Vegas where you have big hotels, big distribution centers? Oh, now, now the refrigeration parallel system is in a, in a, in a box in a house outside, 300 feet away.
• 0:25
  But the compressor guys say, no, no, no. My max guys, my max RGT return gas temperature is 65. So there are many times in recommissioning I've gone into a store, a problematic store, Costco, Walmart, target since, hey, I can't get this store to run. So I have to go out there and the first thing I'm looking at is how I just walk it on the floor.
• 0:26
  Super heat. 'cause the compressors are the heart of the system. That's what you're trying to keep alive. It's not just the food quality. It's the compressors and the oil breakdown. That's what's pumping all of that stuff. So remember that there's a relationship is my point. And just note that relationship when you're walking into a system, and again, it doesn't manufac manufacture, these are just simple basics that you should look at.
• 0:27
  You gotta check each and every one individually. You gotta check all the head temperatures, the discharge, the suction, the pressures, the oil. And it's, it is a lot of work and it doesn't take that long after you learn how to do it. But a lot of people don't do that. So, and I'm glad that you put that and you said that because when you do have a 300 foot run or a 400 foot run,
• 0:28
  So the reason that's important and in comparison between compressor manufacturers, so in Carlisle specifically, it's in the internal design of the compressor. So a Carlisle, when you're pulling off a valve plate on the top and the bottom of the valve plate on a Carlisle, they're both metal gaskets.
• 0:29
  When you go to a Copeland, you have a metal gasket on top of the discharge and on the bottom you have a fiber gasket. On Bitzer, you have a fiber gasket. So in the compression cycle they use the fiber gasket specifically, right? So that in the event you slug oil or liquid, right when you swab oil or liquid, that that fiber gasket will break before you bend a connecting rod or when you blow that fiber gasket, right, that's basically their way of protecting it. Where what happened in Carlisle was they have an internal passage of the compressor, and so when that liquid or oil or liquid slug would come back.
• 0:30
  So if you go into a store right away and you see that the Y 10 37 is injecting, or the Copeland is injecting its liquid, you know that your rgt is low on gas, bad superheat, something of that is happening in the system in order for you to have that injection. And I noticed that right away. So that's very obvious when you start to see that when you walk right into a compressor room.
• 0:31
  I like to say two 50 all the time because why would I push it to the limit? Why do I take, well, because my car has red line, tachometer says 7,000. Do I wanna go 7,000 RPMs on my card? No, I don't wanna run my engine at 7,000 RPMs. So just because I can, I always committed myself to my own standard as a tech because I didn't wanna call back.
• 0:32
  Trevor: Yeah. And I totally, I totally agree.
• 0:33
  We work on smaller motors and we don't think of it the same, but you wanna have a baseline, you wanna keep that. So then you know when your store starts to go out. I did I think back in 2012 was the first time I worked on some targets. 20 11, 20 12. Mm-hmm. And they had a great maintenance pro program.
• 0:34
  Andrew: I got a question. I, my name's Andrew supermarket refrigeration guy. And yeah, I was very interested in your super eat coil. Super eat when you have a long run.
• 0:35
  Once I commission that set of evaporators that's on that group, I go back and I say, okay, if I in the manufacturer's spec of that 65 degrees, if I'm there, I use, just to be honest guys, the way I would service stores, I like to keep my stores at 55 degrees. It's not gonna hurt the compressor. It keeps my oil a little bit more chilled.
• 0:36
  'cause I'm fully loaded in that case, right? But I gotta be careful because I don't want flood back. So how do I prevent flood back but service and commission the store correctly, I can finalize that checks and balance by that compressor superheat, right?
• 0:37
  If each one of those are different distances, let's, first on your question, put 'em in a box that says they're all on the same suction group. I can't answer that question. If you're telling me that the short one is on plus 18 on a different set of compressors than the plus 25, right.
• 0:38
  Remember you have this liquid feed. So the liquid is, let's say you have, let's just use two runs to make it simple. 'cause we're, you know, it's hard to communicate on a call, but let's say you have a a hundred foot run and a 60 foot run. So the 60 foot run is closest to the compressor room, right? So the liquid gets sent out with this pressure, does it automatically make a 90 degree turn to go to the 60 before the hundred?
• 0:39
  Ah, okay. So by process of elimination, you are gonna start to determine, right? Because you've gotta get that 85 degree RGT that you came up on. Well, is my receiver level good? Yeah, I'm at 20%. I have liquid, I'm feeding. The only ones that are starving is the 60 foot lineup and not the a hundred foot lineup.
• 0:40
  Andrew: Well, this is okay. This is, this is great stuff. So now, now I got more additional questions if you don't mind. So yeah, fire away. Yeah. So when that system, that lineup goes into defrost now you just lost that cooling basically, but it's hard to say. So on your example, if you lose that circuit, 'cause it goes into defrost or you have to shut it off for repair, what is that?
• 0:41
  Liquid gas, now you're starving. That a hundred foot lineup. You're absolutely right. But if your a hundred foot lineup is not alarming, right? You're not getting any case alarms, you're holding temp, right? You have a liquid receiver level, but that would tell you right away if you went back up to 85, oh my gosh.
• 0:42
  It could be that closest, closest case that 60 or so. Good stuff. Good stuff. Rob, we could, we could talk all night here. We could be diving into oil. I think we'll get you come back on and we'll do another oil session maybe. 'cause that's what we're gonna start off with. But I think this was really good.
• 0:43
  Trevor: It's happening now. Right now it's outside where it, it was zero this morning. So 32. Right. So we're at that point where she's going, she's gonna start to climb up to the roof. Right? It's getting cold up there. Yes. Yeah. I love it. So as we got one last question, Frank. Thank you for the question. We have trouble with a system that gets the TXV strainers clogged often, even when oil changes are made.
• 0:44
  And then we went to 4 0 4, it was like, change the filters the first 24, then change the filters to 48 and then change the filter 72 and then two weeks later, back changing them again. And if we would've just purged Yeah, we wouldn't have had to do any of that stuff.
• 0:45
  And then that's when you, you start having some oil issues. Rob, this has been awesome guys. I wanna, I want to give a shout out to Rob. Thank you so much for taking the time. We'll do this again. Thanks for everyone showing up for the community meeting. Love this stuff. Any final thoughts, Rob?
• 0:46
  Speaker 2: And if you wanna learn more about refrigeration mentor, head to refrigeration mentor.com. If you wanna get into the community, check that out. Refrigeration mentor.com/hub. We have a ton of great. Experts this is what the, the community is all about, is to really share the knowledge, to help you grow a little bit faster and actually help you grow along your journey.