Latest / The Refrigeration Mentor Podcast / Episode 319. Avoiding Costly CO2 Design Mistakes with Chris Griffiths

Transcript

Episode 319. Avoiding Costly CO2 Design Mistakes with Chris Griffiths · The Refrigeration Mentor Podcast

• 0:09
  Trevor Matthews: Welcome to another Co, 2 design fundamental training yesterday, if you weren't here at the the session for sure.
• 0:20
  Trevor Matthews: this one here is gonna help us. Because we talked about some quick design yesterday. Today we're gonna be diving into avoiding costly mistakes because we've seen this time and time again. And Chris seen this tons of times on making one small adjustment, can cost a lot of energy or cause a lot of issues. We've talked about a few of them yesterday, but we're gonna be diving into it deep today. Chris. How you doing, brother?
• 0:47
  Chris Griffiths: Very well, Trevor, thanks for having me back, looking forward to this one as well. It's a bit more of a storytelling one as much as anything today. Thankfully, none of my personal designs have suffered these issues.
• 0:59
  Chris Griffiths: but it's not that easy to avoid sometimes. So having these things in mind is always useful to have. So hopefully, it's going to be a beneficial session for those who are able to watch.
• 1:14
  Trevor Matthews: Awesome. I'm excited.
• 1:16
  Chris Griffiths: Right? Shall we dive straight in.
• 1:18
  Trevor Matthews: I think so, because these are just some of the things that we've that is so important key to design. And when you're learning and developing Co 2 design. You want to see what you don't want to do for sure, you want to learn how to do it. But you want to learn what not to do as well.
• 1:35
  Chris Griffiths: Definitely. So today, we want to avoid any costly Co 2 piping mistakes. And I mean, costly can range from, you know, the actual cost of. Maybe you've got piping, which is too big. Maybe you've spent more money than you need to. Maybe you've sized it too small. You have an excessive suction pressure drop. And now your compressors are running more in a worse condition.
• 2:01
  Chris Griffiths: Maybe it's
• 2:02
  Chris Griffiths: time spent in having to retrofit and upgrade pipe sizes or remove pipework sections that were installed incorrectly. All these things cost time and cost money. So let's have a look at what tend to get. So
• 2:15
  Chris Griffiths: I find it's generally 5 things which what we can class, as you know, a mistake.
• 2:21
  Chris Griffiths: So if we size our pipe work too small, we're not going to get enough mass flow through the system. So we're going to have insufficient cooling capacity.
• 2:29
  Chris Griffiths: We can also get that if oil migrates to an evaporator where it's going to want to go. It goes, tries to get to the coldest spot. If there's no oil management system installed.
• 2:40
  Chris Griffiths: and we have to encourage it back. If our pipe work isn't designed correctly, that oil will not return
• 2:47
  Chris Griffiths: with excessive pressure drop, we'll get a loss in efficiency. Our compressors will run at Lower Sst lower saturated condition, and have to do more work to lift it to our condensing and our discharge temperature
• 3:01
  Chris Griffiths: of excessive installation costs. If we size too large, or if we take a route which isn't planned very well, not liaising with other services. So, for example, sprinklers duct work, etc, try and have a sensible route through a store rather than having to weave around everything. Introducing more bends, more pressure drop
• 3:24
  Chris Griffiths: regarding materials, particularly with Co. 2 is even more of a risk than it's ever been before. But over pressure as well. Making sure our pipe work is actually fit for purpose, and can accommodate the pressures we're working with
• 3:37
  Chris Griffiths: for those who aren't too familiar with Co. 2, but are familiar with other refrigerants. For example, 404 a you tend to have for a chiller system a suction pressure of about 3 bars. It's about 45, 50 psi
• 3:52
  Chris Griffiths: and a discharge pressure of about 20 bars at most
• 3:56
  Chris Griffiths: well, our suction pressure on the Co. 2 system will be 28 bars. So it's higher than generally the highest discharge pressure. You would get on 448. You're getting up there for the discharge pressures on air conditioning systems 410, or 32. So we need to accommodate that in our pipe work selection.
• 4:15
  Chris Griffiths: And then, if we undersize our pipe work, or if we have too many short radius bends, we can get noise and vibration occurring from pipe work, particularly on liquid lines. If a liquid line is sized too small and our velocity is too high. When any valve decides to shut fully. You'll get all that energy having to find its way somewhere to go. It's not just going to stop moving without dispiriting that energy that will go into the walls of the pipe, into the valve body, it will
• 4:44
  Chris Griffiths: potentially corrode the inside walls of the pipe. It will damage that valve over time, and it's unwanted. It will be costly to replace.
• 4:53
  Chris Griffiths: So with all these issues, the main ones we want to look at are what happens to inadequate oil return design.
• 5:00
  Chris Griffiths: incorrect material selection, and pull out and routing for a store.
• 5:06
  Trevor Matthews: And that's, I think, an incorrect material selection is something that I've seen multiple times in different ones, training courses from our design to my other Co. 2 courses, because.
• 5:17
  Trevor Matthews: like K, 65 or xhp, whatever it is at high pressure copper, a lot of technicians don't don't know about it, and it looks the same, you know. It's the same length it looks, and it is heavier, you know. If you look at it closely, you can tell. One has a bigger diameter than the other. The big thing is is that man. When I worked on lots of construction jobs we would just grab pipes and pull them in, and just go start
• 5:43
  Trevor Matthews: putting them in. But I've heard of stores where they put all K copper on the high side, and that is something you cannot do. And as a designer you need to make sure, when you're designing, drawing this out, that you label it correctly after you do the design so that they understand what it's what you need to put in there. Because you're in Canada, you have to use stainless steel. You're not using any high pressure copper on the discharge lines.
• 6:08
  Chris Griffiths: Definitely again, where you are in the world will depend on that, because in the Uk we can use K. 65 on the high side, but it has to be rated at 120 bars pressure, whereas normally we'd also get 80 bars pressure pipe.
• 6:20
  Chris Griffiths: which we'll happily do the sales floor. But even then we're now getting systems which operate at 90 bars out of the intermediate side through to the liquid. So we're now having to install extra high pressure. K. 65. Pipework rated to 120 bars to accommodate those liquid lines, and it just keeps going up and up and up.
• 6:38
  Chris Griffiths: and also depending where you are in the world. You may have to use stainless steel app as mandated by local codes rather than just being good engineering practice.
• 6:46
  Chris Griffiths: So 1st offer, we're gonna dive into inadequate oil return design.
• 6:52
  Chris Griffiths: So main thing in piping design is, we want it to slope downhill
• 6:58
  Chris Griffiths: on our suction line to encourage oil, to return with gravity.
• 7:02
  Chris Griffiths: If we don't, we have to try and force it
• 7:06
  Chris Griffiths: alongside and trained in refrigerant, particularly when we work against gravity. So we're looking at suction risers.
• 7:13
  Chris Griffiths: So if we don't
• 7:16
  Chris Griffiths: effectively all the oil that's in our system, we don't have a correctly installed and maintained oil management system. We need to encourage our oil to return at all times
• 7:27
  Chris Griffiths: with a correct oil management system. We should be able to rely mostly on it, staying around the compressors at least, and then just encouraging any small amounts of oil that flow out of the system. To return with a condensing unit with Co. 2 condensing units nowadays with rotary compressors. They don't hold a lot of oil inside them, if any. So you'll find that oil migrates out of the condensing unit away from the compressor
• 7:51
  Chris Griffiths: and finds its way to the evaporator. So they'll have control systems normally in place now. But every so often the condensing unit will talk
• 7:59
  Chris Griffiths: to be evaporators, expansion, valve, Controller.
• 8:03
  Chris Griffiths: It will tell that valve to open completely full, allow all the liquid to flow through and carry that oil, displace it and take it back to the condensing unit
• 8:13
  Chris Griffiths: with multi compressor systems on racks. We want to just encourage it to return using suction risers as shown. So I've got an example here on right hand side of what I class good practice
• 8:26
  Chris Griffiths: and poor practice.
• 8:28
  Chris Griffiths: So our good practice on the left hand side, unfortunately, has a cage in front of it. But I thought, that's a very nicely installed trap is we have a proper oil trap installed on this riser.
• 8:41
  Chris Griffiths: it falls below the lowest point of the pipe, feeding into it so
• 8:46
  Chris Griffiths: at times of part load that will fill until pressure behind builds and forces it back up
• 8:53
  Chris Griffiths: on the right hand side. We're going against gravity, but
• 8:57
  Chris Griffiths: it does not have a trap at the bottom.
• 9:00
  Chris Griffiths: Oil will find its way back into the evaporators. Instead, when it reaches periods of low load, and then it has to try and force its way back out of the evaporators, and then up that riser as well.
• 9:11
  Chris Griffiths: It just leads to more likelihood of oil logging in those evaporators, reducing the cooling performance of the coil, because it's now got insulative fluid inside it as well
• 9:23
  Chris Griffiths: and reduce system capacity.
• 9:26
  Chris Griffiths: That's if we don't encounter compressor issues before that, because we've not got enough oil in them to lubricate the compressors.
• 9:33
  Chris Griffiths: Co. 2 is a bit more forgiving than Hfc. In this sense
• 9:38
  Chris Griffiths: it's much denser at the conditions we use, and it's very.
• 9:42
  Chris Griffiths: It's a very good refrigerant for returning oil in training it and working against gravity
• 9:48
  Chris Griffiths: generally. This means when we're doing our pipe sizes, but we can get away with lower velocities. We don't actually have to as much energy through velocity of a fluid to carry the oil back to where it needs to go, but we still need to consider it so we still have our rules of thumb for design velocities as we touched on them slightly yesterday.
• 10:07
  Chris Griffiths: But making sure that's actually implemented on site is very important. I've known of sites where the designers have designed it correctly, and they've shown rises. Maybe one or 2 pipe sizes down, as you typically would.
• 10:19
  Chris Griffiths: and the installation engineers on site just being well.
• 10:23
  Chris Griffiths: we've not got our pipe. Let's just use that pipe instead. But we haven't got to get reducers as well.
• 10:29
  Chris Griffiths: Well, you're risking a lot there. It might be sized perfectly well to accommodate a full load, but when we get down to part load conditions. There's not going to be any velocity behind that to try and return that oil. So making sure it's actually designed effectively is important. There.
• 10:47
  Trevor Matthews: I I totally agree with that, and I think this comes back to any refrigeration design practices.
• 10:54
  Trevor Matthews: Getting in there talking with them, how how to pipe it properly, because some sometimes people installing are new to it. And it's so important to have those traps there.
• 11:06
  Trevor Matthews: I really, I've seen it on old Renaults that I used to do, where sometimes they did not have any insulation. They did not have traps. They're like, oh, it's only 3 and a half feet or a meter. We you don't really need a you don't need a trap for that, because it's not not high enough.
• 11:24
  Trevor Matthews: but I've seen when I cut out coils before. They were just full, like the whole bottom of a evaporator. Full oil lots of times.
• 11:31
  Chris Griffiths: Leave your oil logged. Just what you want to do when you're ripping them apart is get covered in 2 litres of oil.
• 11:37
  Trevor Matthews: Yep.
• 11:39
  Chris Griffiths: So onto, basically, how can we actually encourage oil to return or not log in our evaporators? So we have our best practices here. Minimum velocities for our horizontal sections of suction
• 11:53
  Chris Griffiths: generally between 4.5 to 8 meters, a second velocity, 900 to 1,600 feet per minute, and on vertical rises between 8 and 12 meters, a second or 1,600 to 2,400 feet per minute. Those are familiar with rules of thumb pipe sizing. Well, no. So those are lower than Hfc refrigerants.
• 12:13
  Chris Griffiths: We will also make sure, on horizontal sections, that we have a proper pipe slope implemented.
• 12:18
  Chris Griffiths: Some people believe or specify as long as it's greater than half a percent or one in 200 fall. That should be okay. I'd rather go to at least a 1% for one in 100,
• 12:30
  Chris Griffiths: so over a hundred inches it drops down by one inch, avoiding oversized pipework.
• 12:37
  Chris Griffiths: oversizing it reduces velocity leading to oil pooling, and.
• 12:42
  Chris Griffiths: as is avoiding costly errors, oversizing.
• 12:46
  Chris Griffiths: you're gonna have more expensive pipe work.
• 12:49
  Chris Griffiths: A large of a pipe as well will generally need to be a thicker gauge pipework as well, because as it expands you have more pressure forcing out the walls, and anyone who's looked at a pressure table for pipework will notice. As the pipe gets bigger, the maximum working pressure at the same gauge is lower.
• 13:05
  Chris Griffiths: So you also need to consider that. Make sure the pipe work is suitable for that scenario, even if it is oversized.
• 13:13
  Chris Griffiths: and then, more importantly, at the design stage. And when you're selecting equipment or designing equipment, if you're in the manufacturing world is including oil separators having actual oil separators sized for the full load of your compressors. Full peak load conditions with that oil throw from either a reciprocating compress or scroll compressor, making sure
• 13:37
  Chris Griffiths: can remove as much of that oil as possible from the discharge gas before it exits that area off to your gas cooler
• 13:45
  Chris Griffiths: at part load.
• 13:46
  Chris Griffiths: You might find that these oil separators are as efficient at doing their job now. And actually, you'll find the oil escapes more apart load conditions than full load conditions. Well, what can we do about that? We could install multiple separators in parallel? We could have one separator per compressor, or feeding into one or multiple oil reservoirs as well.
• 14:08
  Chris Griffiths: So looking at these conditions at full load and part load is very important, because oil part load condition is where oil management is more important. In my opinion.
• 14:18
  Trevor Matthews: Yeah. And I think in piping design, I know a module 10 of the 12 week course when we dive into oil management, sizing those oil lines is is so vital as well. So we're talking more in the refrigerant side as this time. But on those oil lines, if you undersize those you're gonna run into a world of issues. And I've seen it multiple times on in conversation, in, in courses where they're like.
• 14:42
  Trevor Matthews: we're just not getting oil and the you know, the oil transfer solenoid the way it opens up. Because when you're designing the oil management, there's 5 or 6 different designs you can do, and which is we talk about in the program. And so you want to understand when that oil transfer solenoid opens up. If that's the design you use
• 14:59
  Trevor Matthews: that needs to make sure you're moving enough oil into those compressors. And then those compressors have certain amount of carryover. You got to understand all that stuff in the piping design of the oil management system, which is a whole different game than designing the piping of the refrigeration system. So it's important, really really important to dive into that stuff when you're doing those sizing.
• 15:19
  Trevor Matthews: Because I know we, we included the oil separator there and the sizing. It's so many times that that you need to sit down, and you gotta make sure that that's correct. Those lines.
• 15:30
  Chris Griffiths: Definitely and 99% of the time you can rely on it and be well, it's been designed correctly. Designers of yeah, equipment are doing their due diligence, but they can't design that equipment to suit every single scenario that's out there.
• 15:46
  Chris Griffiths: So if you do find an odd site and you're scratching your head, thinking, why isn't this working? At least, if you know how to size an oil separate system, you can do your checks to see. Is this the correct system for that application for that site? So again, the large industrial equipment you might need multiple separators in parallel. Sometimes you might get away with one, or you may need.
• 16:08
  Chris Griffiths: Well, you may need to have several just to accommodate full mass flow at full load conditions. If we're talking, you know half a megawatt up to a megawatt of cooling. There's no oil separator out there which will do that in a single separator. You're going to need multiple.
• 16:24
  Chris Griffiths: So I've put a little design tip here and that is, use manufacturers supply or simulation software and validate oil return velocity, reach out to the manufacturers, give them the conditions you've got and get them to verify it. Reach out. They'll be the experience as much as you are. They've ones who designed it. They know what conditions it's been tested at before it's been manufactured and placed into the field.
• 16:49
  Chris Griffiths: You use them to your advantage.
• 16:56
  Chris Griffiths: So material selection
• 16:59
  Chris Griffiths: hopefully, those present will understand that the pressures inside a refrigeration system can be above atmospheric pressure and anything above atmospheric pressure poses a risk
• 17:10
  Chris Griffiths: regardless of whether it's a 1 3, 4, a system at 1.1 bar suction or Co. 2 system at 130 bars discharge
• 17:18
  Chris Griffiths: anything pressurized can be dangerous. But as long as we design for it, we can accommodate it.
• 17:24
  Chris Griffiths: So with Co 2, because people, I'm not going to say it's a new technology. It's been around for a long time, but the components on markets haven't been there until very recently in the last 1015 years. As such.
• 17:38
  Chris Griffiths: Making sure you're using the correct stuff is very important. So
• 17:42
  Chris Griffiths: when you're looking at pipework selections, whereas before you may have been able to use one type of pipework for the entire system. Now, generally, you're going to want to use multiple different types, or you may pick the highest rated one for simplicity. But you'll incur a cost penalty for doing so. So typical pressures we're expected to design to on our low and suction side are between 45, and 90 bars. Yes, huge range there generally up to 60 is good.
• 18:10
  Chris Griffiths: and we'll accommodate 99% of scenarios now. But as pressures are increasing on the intermediate side for efficiency purposes, we may want to protect the evaporators up to the same level.
• 18:23
  Chris Griffiths: As for our liquid or intermediate side, 60 to 90 bars, depending on how we float the pressure inside our liquid receiver and the quality of liquid we want to send to our evaporators.
• 18:33
  Chris Griffiths: and then on our discharge and gas cooler
• 18:36
  Chris Griffiths: traditionally up to 120 bars. Now, up to 130 manufacturers are coming along
• 18:43
  Chris Griffiths: where ambient temperatures are increasing, and if you're in warmer areas across the globe, you'll get more efficiency or more capacity out of 130 bar system than 120 bars. That's very, quite an in-depth topic to go into. So it's 1 which we tend to leave for course, because we could spend hours talking about that. And the one there's a bit pressure enthalpy chart associated with it. But basically, when you're designing a high side look to get those high pressure materials.
• 19:09
  Chris Griffiths: so making sure that they must meet or exceed that maximum allowable working pressure that Ps. But, more importantly, as well, or just as important, it needs to be compliant with local regulations. So we've got the pressure equipment, safety regulation in the Uk pressure equipment directed in the EU and asme in the Us. And wherever you are in the globe you'll have your own specific types. It's where it's important as a designer to know exactly what you're dealing with
• 19:35
  Chris Griffiths: and all your local codes, and being just as up together on the legislative side as the actual fundamentals of thermodynamic side.
• 19:44
  Chris Griffiths: So I've got a quick selection of pipeworks here where they're appropriate. So K. 65 is the material you'll tend to find on refrigeration systems, particularly for the suction and liquid sides. They'll work up to 120 bars, providing you specify that type of type of K, 65.
• 20:03
  Chris Griffiths: Stainless steel.
• 20:05
  Chris Griffiths: See? Very, very good across a whole range.
• 20:09
  Chris Griffiths: Very expensive of
• 20:11
  Chris Griffiths: carbon steel. Again, it's going to depend vary on that schedule and the diameter of that pipe wherever it's suitable, also needs treating
• 20:20
  Chris Griffiths: when it's implemented, because they can corrode and standard copper up to 60 bar, so you could theoretically use it on
• 20:28
  Chris Griffiths: low pressure, low temperature suction pipe work.
• 20:34
  Chris Griffiths: Would you want to rather put the extra, you know extra security in K. 65.
• 20:41
  Chris Griffiths: One thing to consider, though, is even though the pipe thickness
• 20:45
  Chris Griffiths: will stay the same between K. 65, and standard copper. The outside diameter remains the same. The inner diameter will change
• 20:52
  Chris Griffiths: because of that thicker wall. You'll have less of an inner diameter on K. 65. So you'll notice an increased pressure. Drop the same length of pipe between K. 65 and standard copper.
• 21:06
  Chris Griffiths: So with all this, you need to obviously make a decision as a designer based on local codes and and the actual system you're installing
• 21:14
  Chris Griffiths: verify that maximum working pressure and the temperature rating because, as temperature increase. If you're in an industrial scenario where you might encounter very high temperatures, you're going to need to accommodate that as well. Making sure you've got sufficient insulation around the pipe work as well. Again, it's very important.
• 21:32
  Trevor Matthews: I think that's a big deal what you just said there. Like as a designer, you want to understand how to make it the most cost, effective and safe for your customers, and that can make a big difference on the type of material use. And so designing for success is key. Because I love the the session where we break it down. On what does this whole system cost
• 21:54
  Trevor Matthews: for a customer, you know, in that in that section. Just okay, these are the types of pipe. This is the price for this amount. I need this many meters or or feet, and then that price difference makes a difference when you're quoting a job, or you're bidding a job against competitors in your design. So always always look at that, and you always have to make sure you're designing it safe. as safe as
• 22:17
  Trevor Matthews: to possible. And look at those codes like Chris, said.
• 22:20
  Chris Griffiths: Definitely don't depending where you are in the world, you might not have access to some of that. Some of those materials, k. 65 may not be available in your market, so you would have to go down route of stainless steel or garden steel.
• 22:31
  Chris Griffiths: Yeah, working with what you're given effectively.
• 22:35
  Trevor Matthews: Yeah, because I've heard.
• 22:36
  Trevor Matthews: I know quite a few systems that use carbon steel in in South America I've heard of. I've seen pictures, and and you know they work and they run. But that's, you know, like you just said, depending on where you're at in the world. You may not have access to that certain material.
• 22:53
  Chris Griffiths: No.
• 22:54
  Chris Griffiths: So the last one I tend to find which causes issues is pull out and routing.
• 23:00
  Chris Griffiths: Whether that is because an active decision by a designer.
• 23:03
  Chris Griffiths: You're normally at the mercy of the architects. If it's a new building or working with what you're given, if it's an old store, things change routes. Change room layouts may be built differently from when they were 1st installed. So, looking at how we need to maybe modify pipe work or route it to try and minimize any risks of the previous 2 issues, mainly on oil management, but also minimizing the amount of pipe work we have on site as well. The shorter the pipe run.
• 23:32
  Chris Griffiths: the less pressure drop we incur, the less pipe work costs. We have. It just makes sense.
• 23:37
  Chris Griffiths: So why, it matters well, refrigeration systems are inherently pressure sensitive and velocity dependent, because both of those things, particularly on the suction pipe, will impact the efficiency of our compressors.
• 23:49
  Chris Griffiths: The longer the route from our evaporator to our compressor, the more of a pressure drop we will get more of a temperature penalty we'll incur.
• 23:56
  Chris Griffiths: and the lower our saturated suction temperature will be.
• 24:00
  Chris Griffiths: So we want to try and
• 24:02
  Chris Griffiths: make sure we're routing pipe work as sensibly as possible. And what's that include? Well, we don't want to have sharp, short radius bends. We try and use long radius bends. We want to still encourage the pipe work to slope downwards, or have to put oil traps in as needs be. What we don't want to do is if you have a building where you're going to have to constantly step down along and step back up around beams.
• 24:28
  Chris Griffiths: you know. For example, if it's an old building and it's got a low ceiling, try and route it. So maybe you go to the outside of the building, run round back in.
• 24:39
  Chris Griffiths: Can you move the plant? Can the compressors be moved to another area of the building. Yeah.
• 24:45
  Chris Griffiths: all these things which need to be looked at as a strategic design early on in the stage of it, rather than once you've gone to site as the pipe works being installed there, and that.
• 24:57
  Chris Griffiths: you know, and this has a big cost on on the actual cost and efficiency. Every one bar pressure drops roughly 2 to 3%
• 25:05
  Chris Griffiths: efficiency loss, and therefore 2 to 3% more electricity, which all adds up
• 25:11
  Chris Griffiths: longer pipe runs require more installation time, more brazing rod. If you're using stainless steel, you'll need a coated welder in there to do that, and they're not cheap, skilled trade.
• 25:24
  Chris Griffiths: You need more insulation. You have more thermal losses, you have more soup heat. It's just
• 25:29
  Chris Griffiths: it's a no-brainer. Keep your pipe runs as short as possible.
• 25:33
  Trevor Matthews: I think this is where we're working with a lot of people doing these retrofits now, because more and more retrofits are happening. And when you under you got to look at the bigger picture as the designer. It's not just the pipe work, and it's not just the sizing. When you take control of a project, and that's your project as a designer. You got to look at the bigger picture. And now retrofits for Co. 2 is happening right now all the time I'm seeing here in North America, lots of them happening. And as a designer you got to look at everything
• 26:01
  Trevor Matthews: cause. If you want to take on a full project, and you may work on a team where you just do the piping, or you may work on the team. You just do the sizing. But for for us we want you to be that project man from start to finish. Understand that whole project through, because that's where you you grow, understand? Because
• 26:19
  Trevor Matthews: under, I think this is going to be a bit over the next 5 to 10 years as designers understanding the retrofit market is going to be huge.
• 26:28
  Trevor Matthews: because we know a lot of stores are already coming up to end of life, you know, 2530 years out there, they're going to need a transition. And now, with all these regulations, with the Ames Act and the end users, already pushing forward towards Co. 2 and towards low Gwp. Refrigerants. This, as a designer understanding how to design for retrofits, is going to be super important.
• 26:54
  Chris Griffiths: Well with retrofits. We're at a stage now where
• 26:58
  Chris Griffiths: both plant and any evaporators all need to be replaced in one go. So it's a big big cost to the end user. So make sure our systems run, you know, have an efficient lifecycle cost and try and keep capital expenditure as low as possible is very important. To make sure you actually sell these systems and install them can't make a system if it's the best system in the world. If it's too expensive to install.
• 27:22
  Chris Griffiths: you're not going to use it.
• 27:25
  Chris Griffiths: Yeah. So what can we do about the poor layout and routing? Well, let's keep to our best practices. So let's minimize our total pipe length.
• 27:32
  Chris Griffiths: There's a benefit to us there as well. We reduce our material costs. We reduce our refrigerant charge as well, particularly on liquid lines.
• 27:39
  Chris Griffiths: Use gentle bends, swepties. Lower pressure drop versus sharp 90 degree elbows
• 27:46
  Chris Griffiths: want to maintain that consistent slope in our horizontal lines for our section. Yeah.
• 27:52
  Chris Griffiths: between half 1% ideally up to 2%. If we can to encourage it.
• 27:57
  Chris Griffiths: want to plan for service access as well. So photo I've got on the right hand side
• 28:02
  Chris Griffiths: store where, halfway after the fact, now a low, you know, a low temperature room then got installed as 2 systems so suddenly. You have an extra 2 pipes trying to fit that into the same service riser.
• 28:17
  Chris Griffiths: I'm amazed they could do it, but they did. But now trying to work on that in future, going to be very, very difficult indeed
• 28:24
  Chris Griffiths: and avoid u traps or double bends. And that's specifically no need for oil. Return just one to chuck on. At the end of that. We don't want to be dropping down by word. Then come back up. If we can avoid it, get to a level, keep along that level until we absolutely need to change an elevation.
• 28:40
  Chris Griffiths: So how can we avoid that? Well, if it's an existing building, go to site.
• 28:45
  Chris Griffiths: actually look, and maybe collaborate with other designers, and for other services for mechanical electrical ductwork, etc.
• 28:54
  Chris Griffiths: And if you have access to it. Use freebie software CAD revit or bim tools out there early in the design stage. Do clash detection, making sure that your pipes aren't going to be traveling directly through a piece of ductwork, because, unfortunately, pipes will be easy to reroute on the ductwork, making sure it's all actually coordinated on site before it reaches installation because
• 29:18
  Chris Griffiths: the cheapest time to change it is before it's actually installed.
• 29:23
  Trevor Matthews: I agree with that so much.
• 29:26
  Chris Griffiths: Perfect. Now that brings us to the end of tonight's or today's
• 29:31
  Chris Griffiths: quick run through of how to try and avoid some issues with Co. 2, piping hopefully. It was useful. So many people picked some of the stuff up from it, even if it's just common sense to many of you hopefully reinforcing it will help you avoid the mistakes in future, or
• 29:46
  Chris Griffiths: pick out mistakes if you see them on site, and know then how to fix them.
• 29:51
  Trevor Matthews: I think that's the big thing about there's. So there's a lot of different options. And I think one of the things is understanding the code as designer. I know I talked to a lot of designers, some that come through the the training programs, and they're like a lot of my stuff is making sure in each province or each state that the code we're following the code because it's different.
• 30:10
  Trevor Matthews: You know, it could be different here, even here in Canada, across the country codes are different, like we have our main national code. But when you get into the provisional code it's it can be stricter, and you gotta follow your local local code. So this is something key, for wherever you're at in the world is that you need to dive into that. And and I'm I'm continuing trying to evolve and understand the code in different parts of the world where Chris and the bill they they got it
• 30:37
  Trevor Matthews: down path for the Uk and Europe. But we're looking at codes here in North America, in Australia, around the world. And we're noticing there's a lot of
• 30:46
  Trevor Matthews: differences. They're not hugely different. But there's differences in the code. And for you as a designer, you need to know what's locally correct for you, or make sure that it's more
• 31:00
  Trevor Matthews: like a stricter code or a higher level of code if you're going to go for it, you know. So and I think that's that's very, very important. And I know a lot of you designers out there are doing that. So keep up the great work, you know, and spend the time to learn it. And it's not always fun. It's not always fun looking this stuff up. It takes time, but doing it right the 1st time. You don't have to do it a second time.
• 31:24
  Trevor Matthews: Love it. Okay, we do have a an advanced Co 2 design course coming up. So if this is something you're interested, ready to take your design career to the next level. As I mentioned in previous sessions, we had over 8 different countries. People from 8 different countries come
• 31:41
  Trevor Matthews: to take this program, taking their career to the next level. I love this course. I've learned so much in the last 3 times we ran it, and once again we're already filling this course up super excited for it, and Chris and I'm pumped up. I'm pumped up for this course. So thank you so much, Chris.
• 31:56
  Trevor Matthews: for taking the time to talk, and the next session is going to be in June, this one here in a couple of weeks. So definitely get in on that one. We're going to be diving into how to size transcritical high pressure valves. What the do's the don'ts, what to look for how to size it for different like summer applications. What you need to look for for when it's in the middle of the winter, and very low temp ambient as well as the next. One's going to be on flash gas, bypass, valve sizing what you need to look for what you need to do
• 32:25
  Trevor Matthews: another game. Changing game, changing session. Chris. Thank you so much. Look forward to seeing everyone at the next Co. 2 design session. Thank you.
• 32:34
  Chris Griffiths: Take care, everyone.
• 32:41
  Trevor Matthews: Thanks. Chris.