Episode 279. CO2 Experts: Superheat - Controls & Common Issues with Chris Griffiths and John Rothery

And me and Chris are always keeping in contact, learning from each other, growing from each other on CO2. And he's was on CO2 experts late last year. And we dove into Troubleshooting co2 system to having piping issue. So if you haven't listened to that in a podcast yet, go check that one out or go check it out on the YouTube channel, because Chris dives into all the top things that we could run into in piping issues in co2 system now today.

And me and Chris are always keeping in contact, learning from each other, growing from each other on CO2. And he's was on CO2 experts late last year. And we dove into Troubleshooting co2 system to having piping issue. So if you haven't listened to that in a podcast yet, go check that one out or go check it out on the YouTube channel, because Chris dives into all the top things that we could run into in piping issues in co2 system now today.

We're going to be diving into really some controls and common issues, troubleshooting and support. And Chris Brangan invited one of his good friends who is really another CO2 experts who really cares about the industry supported thousands and thousands of technicians out there and really cares about helping others.

And this is what I love about our industry and the people that come here and come and share their knowledge with us. Is that we really want to help the industry grow, uplift the industry. Chris, John, welcome to CO2 Experts. How are you guys doing? I'm doing great,

And this is what I love about our industry and the people that come here and come and share their knowledge with us. Is that we really want to help the industry grow, uplift the industry. Chris, John, welcome to CO2 Experts. How are you guys doing? I'm doing great,

We're learning out in the field and what works, what doesn't work. And then you move the law, you know, you, that you continue to journey along, just like all of us, we all started at Chris started in the field. I started to feel you, and then we moved their journey along. And I talk about this with technicians all the time is like, this is where when you're in the field, get as much experience, throw yourself at things that, you know, make you uncomfortable.

We're learning out in the field and what works, what doesn't work. And then you move the law, you know, you, that you continue to journey along, just like all of us, we all started at Chris started in the field. I started to feel you, and then we moved their journey along. And I talk about this with technicians all the time is like, this is where when you're in the field, get as much experience, throw yourself at things that, you know, make you uncomfortable.

Because when you learn that on call or when you have those big problems and you figure that out, that is going to just set you up. Along your journey, because now you've been supporting technicians working for a large manufacturer, just really helping the industry grow because you've been doing this 26 years good on your brother. You're still in it plugging away and I'm hoping you're still loving it because I still love it. I still love it.

And I love that. And that's the thing we're here to help support you to get to your next level. This, our industry is not a massive industry, you know, so we're here to help each other grow. That's what refrigeration mentors all about. Omega solutions, Chris, super excited about our conversation today, brother.

Because we're going to be diving into more technical aspect of CO2 and things that we really want to understand some common issues to really help people who are listening on the podcast, watching on the YouTube channel. And once again, rewatch this, and if you're seeing this you know, posts on social media.

Like this post is a comment on any of these social video clips that we put out there because we want to share this knowledge with more people. We get in front of more people and they want to start learning about CO2 or start learning about refrigeration. That's what we care about. We want to help others. So Chris. How you doing brother?

Condensers last year, piping problems. It's actually something both John and I had encountered several times in the past on existing installations worked through together to come up with solutions, identify whether it is undersized or whether it's an issue of the actual, or even the expansion valve.

Condensers last year, piping problems. It's actually something both John and I had encountered several times in the past on existing installations worked through together to come up with solutions, identify whether it is undersized or whether it's an issue of the actual, or even the expansion valve.

And to be fair, some of these issues we'll run through today on superheat can also manifest as issues in pipe sizing as well. So, so a good way of just being able to confirm what are we looking at and how to overcome it.

When we talk about soupy, we're talking about a temperature of a refrigerant when it's raised above its saturation temperature at a specific pressure, this will vary per refrigerant type. and also for each application. Controlling it ensures we have sufficient heat absorption within the evaporator to actually absorb that heat when we need to produce our cooling effect whilst preventing liquid refrigerant or anything which hasn't boiled off yet from reaching the compressor.

When we talk about soupy, we're talking about a temperature of a refrigerant when it's raised above its saturation temperature at a specific pressure, this will vary per refrigerant type. and also for each application. Controlling it ensures we have sufficient heat absorption within the evaporator to actually absorb that heat when we need to produce our cooling effect whilst preventing liquid refrigerant or anything which hasn't boiled off yet from reaching the compressor.

So it protects our system at the trade off of slightly less efficiency by not having a completely flooded evaporator. Boiling off in the evaporator is what we call a useful superheat. So when we talked about pipe sizing before, we raised up a term of useful superheat versus non useful superheat. Useful superheat is anything inside the evaporator which boils off at refrigerant past its saturation temperature.

Non useful superheat would be anything which then gets absorbed between the outlet of the evaporator and the compressor. Too much of that will cause the compressor to be, literally, have insufficient cooling going to it, which will result in high discharge temperatures and affect the properties of the oil and refrigerant in the system.

Non useful superheat would be anything which then gets absorbed between the outlet of the evaporator and the compressor. Too much of that will cause the compressor to be, literally, have insufficient cooling going to it, which will result in high discharge temperatures and affect the properties of the oil and refrigerant in the system.

That's a bit beyond the scope of this, so let's just look at useful soup heat and how we control that. That's calculated as the difference between that refrigerant's actual measured temperature, which we could detect with a probe or a sensor bolted onto the pipe, and then that saturated temperature at the same pressure.

If I can arm it on a TXV, it will sense that CP basically just by the refrigerant in the little vial sensor increasing and decreasing in volume as the temperature on that pipework changes. With the electronic expansion valves, we only have a probe, we have a transducer, maybe to measure the pressure, and then we need to have a controller which then converts those signals into the actual, process to drive open or close our expansion valve.

If I can arm it on a TXV, it will sense that CP basically just by the refrigerant in the little vial sensor increasing and decreasing in volume as the temperature on that pipework changes. With the electronic expansion valves, we only have a probe, we have a transducer, maybe to measure the pressure, and then we need to have a controller which then converts those signals into the actual, process to drive open or close our expansion valve.

On the right hand side, we've got a very, very basic image of what a evaporator coil will be. Refrigerant will flow in, and as it gets towards the outlet, it will start to boil off. Just showing us a change in color on here, just to give a bit of a visual indicator. And as with the Intel, we Control it, we can have issues of low superheat or high superheat.

So typically rule of thumb, we want probably between four and 10 K superheat on electronic expansion valve different evaporators and different manufacturers out there will call for different values to be used in their systems to obviously control it and maximize what they class as usable heat transfer through their coils versus risking possibly liquid flooding back to your compressors.

So, when we talk about low superheat, no refrigerant has boiled off, so there's obviously no chance for it to heat beyond that saturated temperature. Another term we use for this is a flooded evaporator. It's completely full of liquid, it's flooded. We get really good heat transfer through this coil, because liquid molecules of refrigerant absorb heat a lot more efficiently than vapor molecules.

So, when we talk about low superheat, no refrigerant has boiled off, so there's obviously no chance for it to heat beyond that saturated temperature. Another term we use for this is a flooded evaporator. It's completely full of liquid, it's flooded. We get really good heat transfer through this coil, because liquid molecules of refrigerant absorb heat a lot more efficiently than vapor molecules.

We get no vapor formation, but we do now risk liquid flooding back. Whereas on the other side, we have high superheat. where that refrigerant is boiling off almost immediately as it goes into the coil. You may be only using 50 percent of it, so usable actual surface area. So we get very low heat transfer.

Whereas refrigerant gets warmer and warmer because it's already boiled off, we have very little or no suction cooling back to our compressors. That then results in high discharge temperatures and high discharge superheat. Which can lead to refrigerant, refrigerants, breaking down and oil damage as well or damage for a much more common on CO2 systems with these high discharge temperatures round the refrigerant breaking down and property, because obviously it's a single chemical compound.

Whereas refrigerant gets warmer and warmer because it's already boiled off, we have very little or no suction cooling back to our compressors. That then results in high discharge temperatures and high discharge superheat. Which can lead to refrigerant, refrigerants, breaking down and oil damage as well or damage for a much more common on CO2 systems with these high discharge temperatures round the refrigerant breaking down and property, because obviously it's a single chemical compound.

So I'm getting a lot of liquid. So it's a flooded. So they were risking, they were flooding back, but they weren't getting the heat transfer out of the coil. So they're, they're like, well, it's not boiling off. You know, so it's not making that not getting that latent change. Could that affect if low super, you could, could that potentially.

Increase the temperature of a case. Have you ever had flooding or would it drop the case? I'd like to drop the temperature. Can you elaborate on that too? When, when it is flooding or that coil that is supposed to, it's supposed to boil off, but it's all liquid in there,

It's unlikely to happen in a, in a system like this, in my opinion I'd be interested to see it might be the different configurations on those. Are they actually designed to operate as flooded cabinets? Who knows? Yeah, I've not got a story to tell about that one. I don't know if you've been caught about in the past, John. So

With larger systems, for more close control, we use electronic expansion valves. Most supermarket applications out there will likely use these nowadays. They may be. So pulse width modulated valves, which just open and shut over a certain period of time or a certain number of time within a timed period.

So say six seconds, if you want it 50 percent open, it opens for three seconds, shuts for three seconds. Or you get what we call stepper valves, which will wind themselves in and wind themselves out to more closely match. The amount of refrigerant, which needs to let through. So if it was 50%, basically it should wind up to be 50 percent of the openable area to allow 50 percent of refrigerant through.

So say six seconds, if you want it 50 percent open, it opens for three seconds, shuts for three seconds. Or you get what we call stepper valves, which will wind themselves in and wind themselves out to more closely match. The amount of refrigerant, which needs to let through. So if it was 50%, basically it should wind up to be 50 percent of the openable area to allow 50 percent of refrigerant through.

It doesn't quite work like that in terms of how fluid flows through a valve. But for the purpose of today, that's as accurate as we need to be. So on a supermarket, each evaporator needs to actually know what the pressure is equivalent to be able to calculate this, to calculate the depending on how much pipework there is.

You may be able to use a single transducer to deliver pressure all the way back at the compressor rack. If it's a small system, it will ping a signal across and measure that pressure every 10 seconds. That may be enough because you've only got 30 feet of pipe work with our velocities. That refrigerant gas is getting back to that very quickly.

There's no delays in measuring pressure versus that, that refrigerant property. On a larger store, say you have a 000 square foot store with 200 cabinets, if you only had one pressure transducer at your compressor rack, 500 feet away, by the time that signal reaches. and sends a signal back to the controller, that information could be probably a minute out of date.

There's no delays in measuring pressure versus that, that refrigerant property. On a larger store, say you have a 000 square foot store with 200 cabinets, if you only had one pressure transducer at your compressor rack, 500 feet away, by the time that signal reaches. and sends a signal back to the controller, that information could be probably a minute out of date.

You could be, you could start pumping your system down by then, it'll have no idea what pressure is supposed to be, and will give you completely inaccurate superheat values. So at that point, you can almost group similar cabinets with a single pressure transducer. On the schematic we have here, we have a transducer on three cabinets, another one shared between seven, and then one for a cold room.

Yeah, it could all be spread out 200 feet apart, but it gives that closer control about that localized pipe work. You could even go further than that and have one on every single cabinet, which I know some manufacturers, some end users do. You get excellent control. And much higher costs as well. So it's a trade off between complexity, control, and cost.

Yeah, it could all be spread out 200 feet apart, but it gives that closer control about that localized pipe work. You could even go further than that and have one on every single cabinet, which I know some manufacturers, some end users do. You get excellent control. And much higher costs as well. So it's a trade off between complexity, control, and cost.

How does that affect all the other cases now with one transducer?

One's the best straight across it, I would say. So if we took that island of seven cabinets, for example, two of them riced up. Five of them are operating. Okay. First point I would look at is it's probably not transducer related. It'd be more of a controller issue in terms of, say it is a CP issue of miscalculating this, the valve opening positions based on those transducers.

Cause if five working, okay. And yet two aren't, well, you can almost rule out the hardware issue there, because otherwise all seven would be faulty.

The risk you've got with a common transducer on an island is if that transducer fails, a lot of the controllers have a backup value you can input. So, say, You know, that, that's set, so all those cases will then go, well, we've all got the same C3, we'll start controlling the same way, you run the risk of getting flood back a lot quicker, because all those valves will then start driving to an inaccurate reading, whereas if you've got one, one transducer per fixture yeah, you can see it quite clearly that, you know, if you've got all that extra redundancy in the system, that if it, if a transducer does fail, it'll be that one cabinet, And if the valve goes into a sort of emergency operation of naught to a hundred percent modulation you're not going to get so much feedback to your compressors.

The risk you've got with a common transducer on an island is if that transducer fails, a lot of the controllers have a backup value you can input. So, say, You know, that, that's set, so all those cases will then go, well, we've all got the same C3, we'll start controlling the same way, you run the risk of getting flood back a lot quicker, because all those valves will then start driving to an inaccurate reading, whereas if you've got one, one transducer per fixture yeah, you can see it quite clearly that, you know, if you've got all that extra redundancy in the system, that if it, if a transducer does fail, it'll be that one cabinet, And if the valve goes into a sort of emergency operation of naught to a hundred percent modulation you're not going to get so much feedback to your compressors.

So that 50 percent could either flood, flood the back to the rack, or it could overheat either, or you don't know, because you're just putting it in a manual. It's like putting overriding into a manual position where it's not going to modulate. Is that correct, John?

So if the transducer fails, you set it to say 20 bar the transducers off, but you still see that reading on your controller. So it sort of hides the issue. If you've got multiple transducers, you can compare one case to another and it. Pretty apparent, you know, that it's not moving and it's just flatlined on your graph.

It's just that it's more apparent now because more people want control, they want visibility, and for me as a technician. It helps me troubleshoot so much faster cases. What are your thoughts on that? Because you do a lot of support, John, on you know, helping technicians out in the field. What are your thoughts on working with the newer more electronic based system versus the older mechanical ones?

It's just that it's more apparent now because more people want control, they want visibility, and for me as a technician. It helps me troubleshoot so much faster cases. What are your thoughts on that? Because you do a lot of support, John, on you know, helping technicians out in the field. What are your thoughts on working with the newer more electronic based system versus the older mechanical ones? Because you've done both. Right. And what are your thoughts on the differences?

It's great for a steer. If I'm seeing flood back, let's be free on something. I can shut it down remotely as well. Protecting the compressors because obviously you've got the big cost if you start getting flood back through a cabinet. You know, for the sake of the transducer. Yeah. And you're risking compressors failing. That's true. It's a no brainer really, but yeah, it's great.

You know, we're in supermarket, we've been doing a long time, but there's still a lot of people out there that are hesitant of all these electronics. And saying it's making it more complicated. Do you feel like it's making it more complicated or it's just overwhelming at first and there's a bit of a learning curve, John?

You know, we're in supermarket, we've been doing a long time, but there's still a lot of people out there that are hesitant of all these electronics. And saying it's making it more complicated. Do you feel like it's making it more complicated or it's just overwhelming at first and there's a bit of a learning curve, John?

You can have your air off looking, you know, lower than your air on, but it's because it's adjusted to scale within that range, because that's what it sees on the probe. Yeah, you've, you've got to be, I don't know, more sort of focus on what you're looking at.

You need to go into the controllers and set up which type it is, otherwise it will not read correctly. And you will get these, these funny values. And yeah, the system, yeah. The system just will not work as it should. And which can lead to some not catastrophic failures, but definitely some big issues. technicians could do without. So yeah, make sure it's commissioned as per all manufacturers set points and recommendations. And obviously a key one to drive home.

And I've read so many control documents and case controllers. It can be confusing because one controller manufacturer says that one way. Another one says a different way, but it does the exact same thing. So it can be confusing. Have you guys noticed that in some control documentations from the manufacturers? Yeah.

Understanding, talking to the right people and then actually. Looking at that problem, not the problem that I was thinking driving through the site. So I appreciate that, John. Understanding, talking to the right people and then actually. Looking at that problem, not the problem that I was thinking driving through the site. So I appreciate that, John.

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All right, so let's jump in. So the symptoms that you can get with CP. So cross ball, both high and low CP, but we'll look at, look at both. So big one, which happens quite often is debris inside the expansion valve. So whether they've been brazing without purging with nitrogen or some, something's fallen into a pipe during installation, it's finally found its way to the expansion and it's just enough to stop.

The valve from shutting fully. And at that point you try and drive a valve down, closed. The signal thinks it's shut, but yet refrigerant is still going through. That's going to be forcing it open, it'll allow excess refrigerant into the coil when it doesn't need it. If there's not enough heat load to boil it off, that liquid is then going to reach back to our compressors.

Slightly along the same lines, an oversized valve where you've got very little, little control at low load conditions. It, the tiniest bit which will open will allow a lot more refrigerant through than it needs to. Again, not enough load to boil it off. Liquid's going to reach back to our compressors. What we'll find as well is if there's oil locked in the evaporator, there's a lot less heat transfer.

It's insufficient heat transfer to boil off because it's, it acts as an insulator. That refrigerant will still go through and again, reach back to our compressors. And then lastly, as we've already talked on, already commissioned. So if those valve parameters are set up correctly, if it's not reading the right transducer range, you'll get overfeeding of liquid.

It's insufficient heat transfer to boil off because it's, it acts as an insulator. That refrigerant will still go through and again, reach back to our compressors. And then lastly, as we've already talked on, already commissioned. So if those valve parameters are set up correctly, if it's not reading the right transducer range, you'll get overfeeding of liquid.

And again, it will reach back to our compressors where we have here low, low CPI always consider is a lot harder to pinpoint the real cause issue of and high CP faults.

And now they're, I'm teaching them how to get into the trend graphs. So looking at the trend graphs, and one of my favorite ones is opening percentage of the valve. Watching the opening percentage, and so you go to the trend graph and they'll bring it up and I'll say, Okay, let's go back three months or four months and let's look at the trend graph of that valve opening and what the superheat was.

And then, then all of a sudden you can start to see the temperature starts to rise up and then the valve is starting to rise up more open. So instead of it running around say 40 or 50 percent, the valve is running at 80 or 90 percent open now to try to maintain the same temperature. So when you're trouble, I find it so much easier to troubleshoot a case when you have all these checkpoints.

And then, then all of a sudden you can start to see the temperature starts to rise up and then the valve is starting to rise up more open. So instead of it running around say 40 or 50 percent, the valve is running at 80 or 90 percent open now to try to maintain the same temperature. So when you're trouble, I find it so much easier to troubleshoot a case when you have all these checkpoints.

Before when I was in the field and on the tools, I had a set of gauges and I put her on one case and my temperature probe and I had Cooper and say yellow jacket and then nothing was logging. So I just seen it at that moment in time and I walk away, go to check another case and then I come back and it's different.

I'm like, okay, well, what's happening now with the trend graphs and these controllers and really any manufacturer now with case controllers, they're doing a great job with the logging features as long as it's set up and you have the temperature probes. It helps me so much and in showing these technicians in this, the, the CO2 programs, they're like, I never thought of that, you know, cause I'm not used to seeing how a TX valve reacts and what percentage the valve, the TX valve is open, we only have a few set set points mechanically to check.

What are some of your thoughts on that, Chris we'll start with you, Chris, and then we'll go to, with you, John. What are some of your thoughts on that, Chris we'll start with you, Chris, and then we'll go to, with you, John.

So I was like, I'll dial into the site, have a look, and you can see it's prop by, by five degrees Celsius every five minutes. Basically it's like, oh one. I was like, well, you're, you're plus two degrees now. You gotta get down to minus 21. You'll be home in ideally at least sort of 25 minutes, or, or you'll get to leave.

I think it took about 30 minutes in the end because someone had opened the door. He's like, Oh, that was great. Now I could pack half my tools away and I have to shoot off. So it's just having a lot of stuff like that. It helps you program your day as well, as much as anything. It can maximize your workforce.

And if you have someone sat in the chain dialing, so that's coming down quite nicely, you know, you probably don't have to wait half an hour before you start really doing your paperwork, start packing your tools away before you start leaving site, something like that. It's in Bali, but I'd love to have had that when I was on patrols.

And if you have someone sat in the chain dialing, so that's coming down quite nicely, you know, you probably don't have to wait half an hour before you start really doing your paperwork, start packing your tools away before you start leaving site, something like that. It's in Bali, but I'd love to have had that when I was on patrols.

So yeah, it's it's good for diagnosis and sort of pinning things down. I don't know.

Yeah, no, and I, I totally, I totally love looking at the train grass. So if you're getting into CO2 and you're starting to see more case control, I highly recommend starting to learn how to read the train grass. Cause it is going to make, it does take a little bit, which one should I use and which one should I be watching and monitoring, but for sure, when you're watching the defrost, when it goes into defrost, out of defrost, into defrost, out of defrost, and you will see these consistent things happen as long as it's fine tuned, because that's another thing that I train, train a lot in my CO2 programs is how to properly fine tune it because when you set it up day one, day three or day four or day five, as now, as people start putting more product in, you get customers in doors, opening and closing.

That could change the dynamic, the humidity in the store, you know, that can change the dynamics of that specific case in that specific location. So it's, I think it's super cool. So and the very first point there, Chris, the debris inside expansion valve, I think that is one of the biggest ones. When I used to work for the manufacturer and do a lot of electronic valve training and I would go to events and I talked to all the competitors, we had the same thing as a manufacturer.

Like most of the issues were debris inside the valves. So this is something that really you want to take a look at because the big mania, all the big valve manufacturers are doing a good job. They got quality control. They're spending millions of dollars to make sure a good product comes out. Do issues happens along the way?

Like most of the issues were debris inside the valves. So this is something that really you want to take a look at because the big mania, all the big valve manufacturers are doing a good job. They got quality control. They're spending millions of dollars to make sure a good product comes out. Do issues happens along the way?

Totally do. But there should be absolute zero dirt debris inside of really in a refrigeration system. You know, there should be nothing, but we know we're super regular for sure. I put a lot of dirt in the systems over here. So just be aware of that stuff. Get, make sure the debris is out of there.

Okay. It's a discharge pressure. Okay. If there's enough refrigerant in the system, still your discharge pressure isn't going to be low. That refrigerant has got to be maintained with held in the system somewhere. Your liquid, if you can check, check the liquid side or intermediate side. You should have sufficient pressure because the refrigerant is backing up within it.

Okay. It's a discharge pressure. Okay. If there's enough refrigerant in the system, still your discharge pressure isn't going to be low. That refrigerant has got to be maintained with held in the system somewhere. Your liquid, if you can check, check the liquid side or intermediate side. You should have sufficient pressure because the refrigerant is backing up within it.

It's not going through the valve and that's what's causing the high CP on the other side. Whereas a system lower refrigerant will be sending that refrigerant through, it'll be boiling off very quickly because, just because it's not allowing an awful lot through, but there's also not a lot behind it either.

So it's having that. Also, if you've got a side glass to check high CP, you'll have no flashing in the side glass or ideally not. System lower refrigerant. You'll see the bubbles in there. There's just not enough refrigerant filling up that space your liquid is already boiled off Well before even reaches the side glass So that's one way of checking also low refrigerant charge would occur across the system.

Whereas incorrect valve commissioning, etc Yeah, or it's not opening enough should appear just on one or two fixtures If it's across the entire system and your site's been commissioned incorrectly. Well, that is it An item there, but hopefully be able to identify that based on, you know, you probably have to dig a bit deeper into it to check.

Whereas incorrect valve commissioning, etc Yeah, or it's not opening enough should appear just on one or two fixtures If it's across the entire system and your site's been commissioned incorrectly. Well, that is it An item there, but hopefully be able to identify that based on, you know, you probably have to dig a bit deeper into it to check.

Yeah, I've done. That ain't fair. A lot of it should obviously be designed to sort of push it out of the gas cooler and, and what have you. Keeping the gas coolers clean. Obviously, checking if you've got false load on the gas curve for a sort of heat boost, that sort of thing.

You know, checking they're not hyped up. It does happen. And you can get the log in. Generally, if yeah, checking charge, etc. You know, if you lose gas, you lose oil as well, so it's always worth comparing the two. An issue I have seen with regards to charge, if you're checking your, you know, your vessel, is the RPRV, your flash gas valve, if you've had power cuts overnight, if it's a brief power cut, the valve starts driving closed, it comes back on, so the valve can actually go out calibration.

So it's always worth checking your valves are calibrated as well, if you're getting sort of oddities with fluctuating levels in your vessel.

So number one thing we found, which also. Relays back to what you just said about the controls and being able to look back historically. How's the problem just started? Well, if not, let's go through our normal checks. Check airflow, for example, make sure it's not a refrigerant is actually able to pick up heat into that coil, check control settings, check if the fans are active, check transducer input, sorry, output values.

So number one thing we found, which also. Relays back to what you just said about the controls and being able to look back historically. How's the problem just started? Well, if not, let's go through our normal checks. Check airflow, for example, make sure it's not a refrigerant is actually able to pick up heat into that coil, check control settings, check if the fans are active, check transducer input, sorry, output values.

So as the transducer converts a pressure signal to a voltage, check that actually relays and relates to. What pressure actually is inside the system. So you may have to put a gauge on to actually physically measure that pressure rather than just relying on what that transducer is telling you. And then also check whether the expansion valve drives open and drive shut.

If our problem has just started, next thing we check is have the controls been changed. Try and narrow it down to whether it's a software or hardware issue. If the controls have been changed, could well be something to do with that. So check those settings and amend if necessary. Monitor it, if the bolt reoccurs.

It's unlikely to be controls related. If the controls haven't been changed, it's been like this since day one, or, sorry, not since it's like this, not like this since day one, but nothing's happened to the controls, it's probably hardware there. So again, check airflow, or, or water flow if it's a pump system.

It's unlikely to be controls related. If the controls haven't been changed, it's been like this since day one, or, sorry, not since it's like this, not like this since day one, but nothing's happened to the controls, it's probably hardware there. So again, check airflow, or, or water flow if it's a pump system. Check transducer output values and check that EEV drives open and shut.

And really in the tank, the pressure relief wasn't going off. He was like, what is going on? So the valve was, the system shut down, but but the pressure relief was like, it was that much pressure in there. And so what he did, he. Took his trans high pressure gauge, put it on the flash tank. And it said 580, he's like PSI.

So around 40, 40 ish bar. And he's like, what, what's going on? So he actually pulled off the transducer and was full of oil. He just emptied it out of oil, put it back on and it re read correctly. So some things can be a little tricky like that. And I've talked to a few manufacturers do a lot of support and they've seen a lot of technicians, like cut valves out or replace valves.

So around 40, 40 ish bar. And he's like, what, what's going on? So he actually pulled off the transducer and was full of oil. He just emptied it out of oil, put it back on and it re read correctly. So some things can be a little tricky like that. And I've talked to a few manufacturers do a lot of support and they've seen a lot of technicians, like cut valves out or replace valves. For actually a transducer issue or a wiring issue to a transducer. John, do you have any experience with that?

One of the issues I've found in the past is that work's been done on a, on a, an island, and the transducer's been left valved shut, and afterwards, and all those controllers are linked to this, but that, that pressure is not changing because it's trapped in that short section of And yeah, results in incorrect.

And Yeah. Liquid flowing straight through, straight back to the compressors. And thankfully not quite large enough island to really damage the system, but needed an investigation. And yeah, that's the issue. So again, it goes back to commissioning checks, make sure it was out, make sure that transducer is actually reading what it should be.

You'd think it would occur to you when it's a consistent. 28 bar, all times for a week. Oh, that system's working really well. That's a consistent suction pressure. No, it's because it's not reading correctly. That's one of the things we can check on our, yeah. If it's a transducer, this sort of Ray touched on is, is there, for example, a difference in pressure between a primary and backup controller we can do that is check that again with a physical gauge put on the system.

And also you can swap between different transducers to rule out a wiring issue as well. If you've got similarly located transducers, check between, does that controller now show a different signal? If so, yes, it's probably not a wiring issue. If it doesn't show a difference, well, that's something, if it sounds like both of those transducers are going to be faulty, it's probably the wiring.

And also you can swap between different transducers to rule out a wiring issue as well. If you've got similarly located transducers, check between, does that controller now show a different signal? If so, yes, it's probably not a wiring issue. If it doesn't show a difference, well, that's something, if it sounds like both of those transducers are going to be faulty, it's probably the wiring.

And then again, if you have a constant pressure reading, where you've got a different value shown by the transducer versus that physical system. So again, we put a gauge on the system. Check the values, which are inputting to the controller. So check the voltage, check that transducer range is set up correctly in the controller.

Make sure it's a, whether it's a 60 bar or 90 bar transducer or lower, if it's a lower pressure system, don't tend to come across even lower than the CO2 nowadays over in the UK where I was in the past and yeah, basically just do your checks and do your due diligence.

Cause there's so many, I trained so many people from around the world in different countries and then I come in and we're learning CO2. And then like you just said, like most of the system you see now are 60, 60 bar. Right. 800 and some PSI standstill pressure where there's tons, all the ones here in Canada, I don't know many that are, that are that high, like we, there are some, but most of them are 40 bar systems, you know, standstill pressure.

So depending on where you're at in the world, you really want to understand that specific system that you're working on. And that is key to your success because I really try to teach technicians that they can go work in the UK, or they can go work in Germany, or they can go work in Australia. But it's understanding that system.

And then, like you said earlier Chris, I really like that point. And well, is that the right transducer? Is that a zero to 60 bar transducer? Is that a zero to 30 bar transducer? And it's not getting the proper range. And so now that valve is working way erratic. So maybe working a little bit, but it's not reading correctly. So the range is off. So the range is off.

Presumably that was off of defrost. Whereas all the other cabinets on that shared header, that pipe work was we're achieving temperature of them. Right. Set a time limit, it's a fault specific to the cabinet. So again, I presume John, you go through, check everything over, strip the valve part and find, and find that, that's a pretty obvious cause there. That's

I think so too. Cause there are some valves out there that don't have filters before it. And I think most of the manufacturers today do at this point, you may not know that like, it may not be like what you're used to in a TX valve where it's very noticeable.

Like this one here is not noticeable. This is inside. You actually have to take the valve apart to look at pump down the circuit safely pump all the refrigerant out and then, you know, reclaim whatever is left in the lines to push it in. And this is what I, this is another thing that I just kind of learned from a technician in the, in one of my CO2 courses.

Is used like Because right now in the UK, if you, you can blow out the CO2, is that correct? Like you, you pump the circuit down, you say you have 12 bar left in a low temp circuit or, or 200 PSI, because that's vapor left you right now, you can still blow it all that CO2 to the atmosphere. It's not against the law anywhere in the world.

I don't think at this point, or there's no, not much regulation, but we can release natural refrigerants. But what a lot of people don't think about that I talk about my training and then it was a really good point a technician brought up in the course, he's like, yeah I say you got to reclaim that, put that back in the system and other technicians, well, why would I do that?

I don't think at this point, or there's no, not much regulation, but we can release natural refrigerants. But what a lot of people don't think about that I talk about my training and then it was a really good point a technician brought up in the course, he's like, yeah I say you got to reclaim that, put that back in the system and other technicians, well, why would I do that?

It's natural. There's no, it's not against the law. This technician told me, you know, Trevor, at one of my sites where we have a lot of reliefs happening, like the po, like it's having a lot of relief. Do you know that there's, all the trees are dead around it now. All the grass is dead around it. And he says, Trevor, it's not.

And he told the group, he told all the other technicians, he said, Trevor, it's not the releasing of the CO2, it's the oil that may be in. That's CO2 that you're releasing out. And so this is why in my trainings, I'm like, get a recovery unit, put it in. And I know it doesn't have, cause when I started out in the fields, you know, it was a different time.

But when he told me that is like all the trees and all the grass is dead around where that relief is. So you guys got to think about that. It's not the, yes, the CO2 is not a problem, but if you got POE flying out with it, because we do, we know we have, in that refrigerant going throughout the system there's POE in there, all that, that refrigerant.

So, just think about that next time that you're relieving CO2 out of the system. Little tangent there. What are your thoughts on that? What are your guys thoughts on that as well? So, just think about that next time that you're relieving CO2 out of the system. Little tangent there. What are your thoughts on that? What are your guys thoughts on that as well?

It's because, you know, we're starting to get systems which are approaching their end of lives. You know, 15 years, you know, yeah, it'd be 15, 17 years. Some of them bear at the end of life, but currently it is, as you said, it is release it to atmosphere rather than try and try and use it again. I know again, global warm potential is way down there, but surely we should be looking at any refrigerant.

It's because, you know, we're starting to get systems which are approaching their end of lives. You know, 15 years, you know, yeah, it'd be 15, 17 years. Some of them bear at the end of life, but currently it is, as you said, it is release it to atmosphere rather than try and try and use it again. I know again, global warm potential is way down there, but surely we should be looking at any refrigerant.

Release is unacceptable. It should be reused because the process has gone into producing that CO2 and using it. Why, why let it go to waste? Why let it into the atmosphere? Let's reuse it. And unfortunately, we haven't got a lot of cases where. Your new system is run up or in a position to run up for your old one is decommissioned.

You could just pull, pull the CO2 over. Unfortunately, in an ideal world, that'd be great, but we don't, but there is nothing out there. And every, every company I've spoke to on this matter just has no interest in actually, actually looking into it and producing something for it. So until regulations laws change, I don't think there's going to be a real drive towards that.

I know we're a little bit off topic here, but, and don't get me wrong, everyone, listen, I've led a lot of CO2 out. I used to do trainers and it was 50 pounds every training that I was letting out. So it's not like I haven't done it. But the thing is we gotta be co cognizant of what we're doing. And when he talked about that, the PO ego, and I'm gonna just kind of clicked for me a little bit more.

So and reclaim, you can use Reclaimers, the reclaimers that you're using now today. You can use that on CO2, as long as the pressure is low enough. Think about 410. If you use a reclaimer for 410, low temp CO2 or subcritical CO2 is the same pressure. So just look into that for the manufacturer of that equipment, because I know lots of technicians using reclaimers for CO2 vapor and stuff like that. That's below the pressure threshold. Okay. So let's get on with some more troubleshooting, Chris.

So one contractor about eight or nine years ago, he was like, Trevor, we use a heat shrink. So they, all their electronic valves in the wet, moist areas, they'll pull a big piece of heat shrink over it. So it will, any water that gets onto there, it doesn't really get into the valve itself. So it reduces some rusting and things like that.

So one contractor about eight or nine years ago, he was like, Trevor, we use a heat shrink. So they, all their electronic valves in the wet, moist areas, they'll pull a big piece of heat shrink over it. So it will, any water that gets onto there, it doesn't really get into the valve itself. So it reduces some rusting and things like that. Water getting into the valve. Probably getting rusted, yeah. Good

And, you know, you could be out at a case that last case is not feeding. You could be looking at the flash tank or, well, the flash tank. So hopefully you understand that the high pressure valve goes into the flash tank receiver, but it could cause some issues as there's other places in the system and you're looking there, but it comes back to the flash gas.

What are some troubleshooting tips, John, that you've used over the years when you're running into like, say a high pressure valve issue like this? What are some troubleshooting tips, John, that you've used over the years when you're running into like, say a high pressure valve issue like this?

You need your high pressure valve, your flash gas bypass valve, and all your EEVs to work in sync. And so when you have those working in sync, you're going to have a system running really, really good, stable suction, stable liquid, and really a stable discharge. And this comes back to fine tuning, which is a whole nother conversation with electronic valves and controls.

You need your high pressure valve, your flash gas bypass valve, and all your EEVs to work in sync. And so when you have those working in sync, you're going to have a system running really, really good, stable suction, stable liquid, and really a stable discharge. And this comes back to fine tuning, which is a whole nother conversation with electronic valves and controls.

So love that.

Some of the end users who invested like a, a remote monitoring system, they can have it. So every, every 24 hours, it just broadcasts that the, what the site conditions should be. So even if you change the component. You can input your parameters, if they're slightly wrong, it will get that updated broadcast to take it back to what, what the condition should be. Ideally that's one way, which is a good time saver as well. If you had multiple fixtures that you've replaced, you just leave it in their capable hands. Assuming they is actually set up correctly, just saves up that time consuming process of going through and inputting 40 different parameters on every single cabinet controller.

Know it's slightly on top of them in terms of CP, but they're like CP and valves go quite closely, hand in hand. And again, there's a lot of valves on the CO2 system. So let's let's discuss them. So perfect with that in mind, Trevor, that was everything we wanted to show today. So again, any questions?

I feel like something needs to change because if it happens, one of the most likely happens again, it's like anything it's you don't want to put a TX ball, but the bottom of a pipe, because you know, oil is going to. It insulated there. I've seen manufacturers where they would put a quarter inch pipe, a quarter inch pipe, a certain distance away.

I feel like something needs to change because if it happens, one of the most likely happens again, it's like anything it's you don't want to put a TX ball, but the bottom of a pipe, because you know, oil is going to. It insulated there. I've seen manufacturers where they would put a quarter inch pipe, a quarter inch pipe, a certain distance away.

So oil doesn't get into the transducer for an example. That's just one example. That might be extreme. But you know, you never want to put a transducer in the bottom of the pipe because that's where the oil is coming back up the suction and could fill it right up. So I would definitely take a look at the piping and adjust if needed. What do you guys think?

It's not like if we just sat it at the bottom. For it rise up a riser, but any oil can pull back down and potentially flood it. That's not always possible on on sales floor fixtures. If you have very high ceilings or inaccessible ceilings, you obviously wouldn't put out there because it does need to be maintained and accessed.

It's not like if we just sat it at the bottom. For it rise up a riser, but any oil can pull back down and potentially flood it. That's not always possible on on sales floor fixtures. If you have very high ceilings or inaccessible ceilings, you obviously wouldn't put out there because it does need to be maintained and accessed. At which point, Ben, as you said, Trevor, actually put it on a stub with a bit of physical height to protect it from oil logging. That's, that'd be my solution.

I'm not sure. The reclaimer would stay online unless the vapor pressure was greatly reduced. If the case or rack is pumped down, the service pressure will equalize to ambient condition using 60 Fahrenheit example. The thing is though, Jason, I'm talking about vapor. So CO2 vapor, it's not going to increase like liquid.

So if you pump down my example, you pump down a circuit, you pump all the liquid out of the circuit, and you only have CO2 vapor inside that. You could use the reclaimer to pull out that, that CO2. So if it's 200 PSI, it's not like it's going to raise up to a thousand PSI in that reclaimer. If that makes sense.

So if you pump down my example, you pump down a circuit, you pump all the liquid out of the circuit, and you only have CO2 vapor inside that. You could use the reclaimer to pull out that, that CO2. So if it's 200 PSI, it's not like it's going to raise up to a thousand PSI in that reclaimer. If that makes sense. Any thoughts on that? John or Chris, did you guys use reclaimer slots in the past?

Yeah, it's got to be something to overcome. I wouldn't. Personally want to use a, a system or a recovery rig, which wasn't rated or tested on CO2 yet, but that's what I'm thinking. The manufacturers need to come up with this, you know, with tool manufacturers. They need to come up with a solution for it. We'll leave it in their capable hands, or I'll do, took meantime his complain.

Yeah. Yeah. And Steven should, that's a good point. Steven says, you'll still, you still got to condense into the cylinder. I'm just talking about pumping it right back into the system. If you can like somewhere in the system, which might or might not be possible standard cylinders are going to.

Very quickly increase the pressure. Yeah. Yeah. I don't even think there's recovery cylinder for CO2 that I know of yet. I've heard of people making them so, but I'm just talking about just pumping it back into the system. So you're not really using any. And once again, we're just trying to come up with ideas here and then make it.

Make it easier for us. And that doesn't make it easier for us, but we don't want to be thrown POE all over the place either. Guys. I love this. Like I learned a ton, John. It was so great to meet you, Chris, as always. I appreciate you taking the time. And I'm excited about all the things coming 2025. We're just getting kicked off here.

It's going to be a good year for refrigeration. It's going to be a great year for, for CO2 natural refrigerant, but. It's going to be great for all the people who are enrolled in our CO2 advanced design course too, Chris. I'm super pumped up for this because over the last year since we started training design, in my background as a technician, I was in the field doing install, just like John, doing service, doing support, work for a manufacturer.

It's going to be a good year for refrigeration. It's going to be a great year for, for CO2 natural refrigerant, but. It's going to be great for all the people who are enrolled in our CO2 advanced design course too, Chris. I'm super pumped up for this because over the last year since we started training design, in my background as a technician, I was in the field doing install, just like John, doing service, doing support, work for a manufacturer.

But ever since I started working with you and Omega Solution and we started doing these design courses, I'm definitely a better technician because now I can understand the engineering behind why something works. And before we end off here, what are your thoughts on that, John? Because I know your background started as a technician over the years.

You have to learn design to support your, your, your team and all of you there. What are your thoughts for technicians starting to learn? Design throughout their career and how can that benefit them?

So it's, yeah, it's key. Really. You need to understand what you're looking at.

If, for example, as we touched on the pipework last time, it's no longer a case of it possibly being a component issue. It is, it's a network infrastructure issue, but without having that sort of theoretical knowledge and understanding how fluid flows within a system and what. Pitfalls can occur. You would never know what to deal with in that sense.

You might have a gut feeling about that pipe looks a bit smaller than I've normally seen connected to this many cabinets, but until you actually understand and possibly have to verify it through software, it gives you that option thing. Actually, that's the correct solution. We'll go down that route.

You might have a gut feeling about that pipe looks a bit smaller than I've normally seen connected to this many cabinets, but until you actually understand and possibly have to verify it through software, it gives you that option thing. Actually, that's the correct solution. We'll go down that route.

It's not the cheapest solution always, but if it guarantees. You know, ideally fault free operation for the next 10 years. How many callbacks have you saved yourself going to site, trying to drain oil out of an evaporator to get the system back up and running? You probably save that amount of money just in oil that you're having to reuse each time.

Yeah, it just, it gives you that full picture of a system. I find design can be, I find there's almost three, three pillars of service as installation of as design and having all three pillars there. It, it, it rounds out the picture. I think it makes you a full engineer that you can be.

Like 100 percent better at troubleshooting system because understanding the design of something, not only understanding the design, but how to design it, and then it gives you a, like it gave me Or help me think differently when I look at a designer. So there's so many big, awesome, great manufacturers that I work with and we work with around the world.

And when you look at each other's design, that there's lots of differences, unique differences, but it's still refrigeration. It's the same. And so if a problem does arise and you understand what their thought sequence was and why they were trying to do something, cause they're always trying to make it better.

It's not like these manufacturer building equipment to make them worse. They're trying, they're trying to make, make it better. And, but when you understand the design side, you can actually go in and plug stuff in very quickly where, you know, at first I thought, okay, how do I size these four compressors for this capacity?

And then all of a sudden I, I plot plotted out and I'm like, okay, this makes sense. Now this is my total heat of rejection. Why have this, this is my discharge, what it should be. And then, you know, you plot that inside the. You know, the different softwares like the, the Bitzer or the Bach or the Danfoss whatever it is.

And then you can see the, either the issues or how it works anyway, for me, design has definitely changed the game for, for CO2. That's for sure. I want to thank everyone for taking the time to come and listen. So once again, if you're listening on the podcast. Hit the, hit the like, hit the share, comment.

And then you can see the, either the issues or how it works anyway, for me, design has definitely changed the game for, for CO2. That's for sure. I want to thank everyone for taking the time to come and listen. So once again, if you're listening on the podcast. Hit the, hit the like, hit the share, comment.

What do you think about this podcast? Or if you're on the YouTube channel, same thing, like, share, comment. This is how more people find out about it. So we really can help the industry grow and get better and learn more. Chris, John, thank you so much for being on CO2 experts and look forward to chatting with you guys again soon. See you everyone. See you everyone.