Piping Pumping Mod Con Boilers

Hello everybody, welcome to our, our webinar. Another Taco Tuesday! It's just another Taco Tuesday. John Barber here with Dave Halldorf and Rick Mayall. We are the, the training team for Taco Comfort Solutions, and we welcome you all. There. Hi Mark Amoroso hangs us. Hello guys. Excellent. Very good. We got about 145 of you out there right now. We got another minute or so to go before it's, before it's go time. Almost two minutes. So just wanted to commit and say, "Hey, how you doing? Welcome everybody." Beautiful day where we are. I don't know about where you know. Rick, you're in Utah. How's the weather out there?

Partly cloudy and probably about 73, 74 degrees. Perfect. Yeah. Hmm. We're mostly sunny and probably about the same temperature here in New Hampshire. And just absolutely gorgeous. There's a golf course out there calling my name. Actually, there's a golf course out there just laughing at me in the back. Angie, how you doing? Corey and Jimmy DePalma says, "It's awesome here in New Jersey." How often can you say that, Jimmy? That's pretty cool. Anyway, so we've got a, we've got a fun, fun hour planned for you here. We're going to talk about piping mod-con boilers and pumping mod-con boilers. And again, we've got two of the best here in the business to help out with that with Dave and Rick to really get into some of the finer points. We got a rainy day in Portland, Corby says. That's how he's got to be. Portland, Oregon. I don't get. Yeah, it can't be raining in Portland, Maine, and sunny here in Exeter, New Hampshire. That doesn't work. Yeah. And Lori's got a great day in Iowa. Where are we in Iowa? Are you from, Lori? My, I have a son in Dubuque. And the interesting, Portland, Maine is nice. We got it. We got a chicken from Portland, Maine. We got a check-in from Alberta. And Lori's in Des Moines, also known as Des Moines, Iowa. But Des Moines sounds more continental. I like that. Yes, Des Moines. How about this? 80 to 80 degrees and 65 degrees relative humidity in El Salvador. How you doing, Ismail? Thank you for joining us. And I've got a nice day in Philadelphia. Sesmar camera. So, so terrific, terrific.

All right, it's high noon. I think we're gonna get this show on the road and welcome everybody to Just Another Taco Tuesday. I'm John Barbican, Dave Halldorf, and Rick Mayo joining us, the Taco Comfort Solutions training team. Today's topic is the piping and pumping of mod-con boilers. One of the things that we've learned, and and Rick actually is one of the really drove this home to me, is that mod-con boilers do not reward your personal creativity when it comes to piping them up. All right? You don't want to get creative. You don't want to say, "I'm bored piping up the normal way. I want to do my own thing." Don't do that with a mod-con boiler. Rick, what does every mod-con boiler come with? Everyone? What does it come with? A knee pad. A knee pad, also cleverly, yeah, cleverly disguised as a manual or an instruction sheet. And they send it to you for free. In that book, there's, there's a diagram. You follow that diagram. 99 times out of 99, it's going to be perfect. That's the way you should do it. Don't get creative with these things. Follow what the manufacturer says. We're gonna be discussing all of that here in just a little bit.

I want to go over a couple of finer points before we jump into the end of the details. First off, on your control panel, everybody, you should see a little hand. Alright? That's just, just if you could click on that and just let me know that you can hear me, otherwise I'm talking to myself here. I said, "Okay, good." Everybody's raising their hand. Excellent. That lets me know that you can hear me. The other thing I'd like you to do, and many of you have already figured this out, there's on your control panel, there's a little cartoon balloon with a question mark in it. That's gonna be how you ask questions. And we want you to ask questions. Ask as many questions as you can. Alright? But what I'd like you to do is just, just click on that and just type in a "hi," "hello," "how are you," "looking good," you know, anything, anything like that works for me. Okay, we got a "hi," we got a couple, we got a "hello," we got a "howdy," we got a "hey, good lookin'." Like, I love this group already. What you got? Very good. Excellent. You good? There you go. There you go. So what I want you guys to do is you can ask your questions and we will stay on, you know, for you to answer whatever questions you may have. So please ask your questions. Type them in here. We'll be stopping every few slides to have to address them. So there's no time, you don't wait till the end to ask your questions. Ask them as they come up and we'll do our very best to answer them. If we have the answers, great. If we don't know, we'll tell you. We're not going to try and fool you or anything. But between the three of us, we've got some, we've got some experience here and hopefully we can, we can answer as many of your questions as we can.

Alrighty, well, let's get started. Okay, let's get this show on the proverbial road here. And again, it's, it's piping and pumping of the piping and pumping of modulating condensing boilers. And some of the things you need to be aware of. What we're gonna cover today, of course, is your basic primary secondary pumping with piping with a twist. Alright? We call this primary secondary piping. It's called primary secondary piping, so you get your terminology right, I guess. You could call it whatever you want as long as you know what you mean. But there's a twist to it with the modulating condensing boiler compared to say, a cast-iron boiler. We'll discuss that. We're going to discuss the importance of boiler water temperature and how just because the system might need 150-degree water doesn't mean you should set up your boiler to make 150-degree water. That's not going to really work very well. So you have to, you have to be able to work that out and figure out exactly what you're going to need. So we're going to discuss how to figure that out. And then we're going to get into detail on sizing that boiler circulator. And there's some interesting nuances that Rick will explain to you, the steps that you want to go through to make sure that pump is sized correctly without being oversized. Alright? And overpumping is a, is a both on the system side and the boiler side can be a real, real issue in hydraulics. It is an issue in hydraulics today. And we want to make sure at least we get that boiler pipe sized properly. We've had other webinars on sizing the system pump properly, which you can go back and re-watch. But this one, we're going to talk about sizing that boiler circulator properly. So let's get, let's get this show on the road. And our first, just diagram for you is your basic primary secondary. Yes, sir. Share your screen. That's going to help. I'm need to do that. Our night. There we go. Thank you. That's why we have backup. That's why we have three of us. If it was up, if you guys weren't here, I would have been 45 minutes into it and before anybody, before I figured out we weren't sharing screens, I've already made that mistake. There you go. All right. Doesn't matter how many of these you do. There's always that one time. So anyway, let's take a look at our first one here. This is your basic moose antler piping. We call it moose antler, you know, for obvious reasons. Okay, kind of sort of looks like a moose antler. You've got your primary circulator. Alright, you get your primary circulator on the system. Alright, and where is my pen? Here's my friend. You get your primary circulator right here. Alright, that is your system's circulator. And then you have your boiler circulator here. And that boiler circulator is pumping into the boiler's heat exchanger. That's important to keep the pressure up in the heat exchanger. Otherwise, under high flow conditions or high fire, high temperature conditions, if you're pumping here and pumping away from that heat exchanger, you might lower the pressure in the heat exchanger. And again, under high temperature conditions, that boiler may flash to steam. We'd like to keep that from happening. So we pump on the return side going into the boiler's heat exchanger for the boiler pump. The system pump, of course, is is pumping away from your point of no pressure change, which is where your expansion tank connects to the system. So in this case, we're adding that circulator's pressure differential to the system. Now, this is showing a zone valve system. You could also do this with zone pumps. You just have a circulator here on each, on each branch. What makes this primary secondary is right here is your spacing between the tees. Your spacing between the tees on your primary branch or your distribution branch and your supply and return for the boiler. Typically, that spacing is anywhere from 6 to 12 inches or four pipe diameters max. The closer the better. It's kind of impossible to put them too close, right? The closer the better. The more you spread them out, the more pressure there is between those two tees, the more likely we're going to have spotty temperature performance. So again, you want to keep those tees as close together as possible, typically six to 12 inches apart. So there's your moose antler piping. Again, it's a boiler circulator pumps into the heat exchanger to keep that pressure up and prevent it from flashing to steam. That's pretty important. All right.

If we had an indirect in the system, okay, it's kind of that, whoops, excuse me, it's kind of the same thing, only different. Everything is the same except when you're piping your indirect, you'll see that we're taking a branch off of the supply into that, into that main, into that main, you know, the distribution loop or distribution header. We're taking a branch off of that to feed the indirect. And then again, we have the circulator on the return pumping into the boiler's heat exchanger. Now, Rick, there's a significance to where those two are, to where that that return line is being pumped. It is being piped into that return branch. What's the significance of that, Rick? Well, I think where you're going with that, it's just that we want to parallel pump into the heat exchanger. Net. Give me some more. I might be able to answer that question. Well, the reason we want them, the reason we want them separate, obviously, is because we want, we don't want them to be pumping in series. Correct? Right. Exactly. That the hints, the parallel into the heat exchanger. The check valves. Very important. Yes. Very, very important. Because you don't, what you don't necessarily want this to be the easier piping, easier pumping route than this. So a check valve right here is very, very important. All righty. Very good. So there we have them with an indirect. Pretty simple, pretty straightforward. And here we have a hydraulic separator. Or if you went with a bigger hydraulic separator, what you'd have is basically a buffer tank. And, and the difference between a hydraulic separator and a buffer tank is simply size. All right? There may be instances where you want a buffer tank if the smallest zone over here is smaller than the lowest firing rate of the boiler in BTUs, then you definitely want a buffer tank to make up for that mass to reduce short cycling. If you know each one of these zones is about the same size as the lowest firing rate, then a hydraulic separator does a nice job for a basic hydraulic separation. Flow on the system side doesn't impact flow on the boiler side and vice versa. All right? So that's, that's basically the job of a hydraulic separator. There are others out there that have might have a dirt separation in them. They might have air separation mediums in them. What you're doing in that hydraulic separator is you're reducing the velocity to, you know, less than two feet per second. Any crud that's in the system might drop down to the bottom, hence you have that, that drain down at the bottom. And when you drop a velocity that low, well, any dissolved gases in the fluid might turn back into a bubble and we'll go out the vent. So that's a dual purpose for your hydraulic separator.

All righty. Now, a lot of people will look at mod-con boilers and if they, they try to make everything the same temperature. Like, let's say we had some, some radiators, some baseboard, some high-temperature radiant, and some low-temperature radiant, all on the same system. We've seen folks try to manipulate the design so it's just all one temperature so they won't have to do any mixing. And that's cool. That's perfectly fine. However, they're missing an opportunity in our opinion. And that if you, let's say you had some high-temperature radiation, again, call it columns, cast-iron radiators, or whatever. And then we had some high-temperature radiant in between the floor joists, let's say we needed 160, 140. And then some low-temperature radiant, maybe in the slab at 110. You might, you will very much benefit from mixing. Obviously, those other two lower water temperatures, but also mixing with something like this. This is a, that's that's called the I-valve. It's the Taco I-valve. And what that is, it's a motorized mixing valve with a built-in outdoor reset control. The reset control is actually built into that head. You just connect it to an outdoor sensor, program it, and it'll figure out what temperature you need. And it will reset that water temperature. Sure, the boiler is resetting off of its reset schedule. But now what we're doing here is we're resetting off of the reset in a multi-temperature, multi-load system. So the I-valve with that outdoor reset is gonna reset off of the reset. The benefit of that, if you think about it, the benefit of that is going to be, hey, when these lower temperature zones or lower temperature areas are calling, I'm gonna be sending even lower water temperature back to the boiler than I would normally. And we know mod-con boilers absolutely dig low water temperature, low return water temperatures. The lower those return water temperatures, the more it's going to condense. The more it condenses, the more efficient it is. So there's a tremendous benefit here to mixing and resetting off of the reset with a mod-con. So, and everything, you don't have to do it, or should avoid doing it. You should try to look for opportunities to do it to enhance the efficiency of the system. Now, that's not saying if that, yeah, if it's all one temperature, you still want to do reset off the reset. Now, let the boiler reset and let you have one temperature and you're fine. But if you're in that multi-load type of a situation with some high-temperature radiation and maybe two different, two different temperatures of radiant, then then you can, then then resetting off of that reset is a really, really, really good idea. All really good idea. Can certainly help. All righty, then. So the bang and the benefit, those low return water temperatures back to the boiler makes everybody a happy, happy person. All righty. Excellent.

Now, let's take any, any questions out there, Dave, Rick, that we need to address right away? I think Dave's answering them and it was, I've been typing a few in. Okay, let's see what, share we can share them with the group obviously, just to see what's what's going on here. The one of the first diagrams that you had with that indirect tank that we were talking about. Yeah. One of the gents was asking if we needed the DHW. Does the primary and the DHW circulator run simultaneously? And no, we don't want them sized to run simultaneously. You just, you're going to have one or the other. So when there's an indirect call, we want that on priority control. Cuz then we want the boiler to go to high fire mode also, right? And the one thing you need to watch out for is make sure that circulator is sized large enough to handle the flow rate and pressure drop through the heat exchanger and the indirect tank at the same time, right? You're gonna need a pretty good set. You more than likely will need a pretty good sized pump there. Absolutely. Yeah. Hey, why do you want to pump through a mod-con boiler? I think we, we addressed that, but I just want to reiterate. You know, we may have a high pressure drop heat exchanger. If you are pumping towards it, then the full benefit of that circulator's pressure differential will be pumping into that heat exchanger. It will keep the pressure up in the heat exchanger as best we can. If we were to pump away from that high pressure loss heat exchanger, we could drop the pressure. You know, we're not, you know, the, the, the circulator's pressure differential is on the outlet side. We could lower the pressure in that, in that heat exchanger to the point where when it goes to high fire, we may, in fact, have an issue with potentially flashing to steam, which we don't want. All right. Again, most similar manufacturers will have that circulator on the inlet, pumping into the boiler's heat exchanger. This isn't an issue of pumping away. We're already doing that with the system circulator pumping away from the point of no pressure change. Here, we're just putting the circulator in the best position for that boiler to operate effectively and safely for a long period of time. Now, some boiler manufacturers have developed heat exchangers that don't have that same kind of pressure drop, and their instructions may be a little bit different. So I, again, always refer to the manual, the manufacturer whose boiler you're using. They'll be that, they'll be the ones to determine where that pump should go. But in most cases, it'll be right there on that inlet side, pumping into the boiler's heat exchanger. Very good. Very good. All righty. All righty. Excellent. Good questions. Getting good questions. All righty.

Here's one. Will a mod-con valve not send some supply water back to the boiler? With a mod-con valve, I guess, if you're asking about that, that motorized three-way valve. Well, no, it's, it's what it's going to do. It's on this supply and it's going to recirculate when it needs to. And some of that return water is going to go back to the boiler. That return water will be much, much lower. All right, then. And then it would normally be if we didn't have that valve there. And that's going to help the boiler and help the boiler condense more. It's a standard three-way motorized mixing valve. The CV on that, on that valve, it's going to depend upon the size. But the three-way, three-way valves are somewhere between, are we gonna say not I'm right here? Are you getting right there? Very good. What are they gonna have? The half-inch a union three-way is 5.7. Three-quarter, 5.8. One inch, 6.6. Okay. So if they're, their middle, middle of the road, they're not, they're not really high pressure drop. They're not super low pressure drop like a four-way valve would be either. But again, depending upon the flow rate you need, it might be just, just perfect. All righty. All righty. Let us continue.

Now, this part is going to be just determining the water temperature. Now, just a couple of things about primary secondary piping. Here's our, here's a little setup. So my system here requires seven gallons a minute at 150-degree water. Okay? That's the load. Right here. That's what we're pumping into our zones. All right? And that system is under, and that's under design conditions, quote-unquote, coldest day of the year. Now, we're designing the system to a 20-degree Delta T. So ideally, when the water comes back, it's going to be 20 degrees lower. And if everything's open, obviously, I've got seven gallons a minute going out. I got to have seven gallons a minute coming back. We're not any flow to the twilight zone here. So if seven's going out, seven's coming back. But if it's a 20-degree Delta T, the water's 20 degrees lower. So on the return side, coming here, I have seven gallons a minute at 130 degrees. Now, we check our boiler manufacturer's specifications, and the boiler manufacturer requires a flow rate through the heat exchanger of four and a half gallons a minute. Now, let's think about this for a minute. I have seven gallons a minute coming here to this first tee. This first tee, I'm yanking four and a half gallons a minute out. Now, I'm gonna ask you guys a question. And type it in. Type it in in your, in your question section. I'm gonna ask you guys a question. If I've got seven coming in and I'm yanking four and a half out, what flow rate do I have in that piping in between the two tees? All right, that piping in between the two tees. What's the flow rate there? All right, let's see. It should be pretty simple to figure out. It's basic arithmetic. All right, seven minus four and a half is two and a half gallons a minute, right? Exactly. And what water temperature? What water temperature will that be? It's two and a half gallons a minute, but what water temperature will we have? Again, should be 130 degrees, right? So I've got seven of 130 coming here. I'm yanking out four and a half of 130 here. And I'm left in that common piping with two and a half at 130. Well, if I've got four and a half gallons a minute going into the boiler to get heated up, what have I got coming back down here? Well, that's gonna have to be four and a half gallons as well, right? If I'm taking four and a half gallons out, I got to put four and a half gallons back in. I'm not losing any flow rate to the twilight zone. What's happening here is I'm mixing four and a half gallons of boiler water and whatever temperature that is, with two and a half gallons of 130 to get seven gallons of 150. The question is, what water temperature does the boiler need to make to deliver to, to give me 150-degree water? All right, what boiler, what, what temperature does the boiler have to make? What temperature water does the boiler have to make to mix with two and a half gallons a minute of 130-degree water to get my seven and seven gallons of 150? All right, we can do an about here. But there's, believe it or not, there is a math formula for that. Better yet, there's two different math formulas for that. All right, there's two different math formulas for that. And we're gonna show them both to you. And it depends on if you're a linear thinker or if you're an abstract thinker. All right, you can use either one. Depends on how you think. All right, I'm a little bit more abstract. Actor. I'm a lot more abstract. So I use this one. All right, FA times TA plus FB times TB equals FC times TC. Before that freaks you out, just think of this. We're in the heating business, right? So we know F and T, right? We know F equals flow and T equals temperature, right? So flow, flow of A times the temperature of A plus the flow of B times the temperature of B equals the flow of C times the temperature C. We already know five of the six variables here. All right, we already know five of the six variables. It's just a matter of how we identify A, B, and C. All right, so you fill in what you know and you solve for X. So A is what is the flowing temperature in the common piping right there. B is the flowing temperature of what's coming out of the boiler. And C, of course, is this is what's what's going out to the system. So finally, I know five of the six numbers. Right? I know the flowing temperature in A, that's two and a half GPM at 130-degree water. I know the flow through B is four and a half gallons a minute. I don't know the temperature. All right, that's the one I got to find out. That's going to be X. And I know the flowing temperature through C, which is seven GPM at 150 degrees. So you just fill in what you know. And then it's, it's fifth grade algebra. So two and a half times 130 plus four and a half times X equals seven times 150. All right, we map that out. 325 plus four and a half X equals 1050. You two salt to isolate, to solve for X. We got to start isolating. So I'm gonna, I'm gonna take 325 from both sides. Subtract 325 from both sides. That leaves me with four and a half X equals 725. And then just divide both sides by four and a half. And that's gonna give me 161-degree water. So I got to set that boiler up to make 161-degree water. Now, again, it can, we can infer this. Can we get close? Yeah, it this way. You know, this way, you know. And that's for the abstract thinker. For the linear thinker, for the more concrete or the linear thinker, there's another way. And, and Rick pointed this out to me this morning. And it was one of those moments. All right, okay. The boiler set point is going to equal the BTU/h required divided by the boiler flow rate divided by 490, which is the density, which is the multiplier of water at a higher temperature on 150 degrees, plus the returned water temperature. All right. So in our example, seven out, seven gallons per minute at a 20-degree Delta T, that's 70,000 BTUs divided by the boiler flow rate of four and a half gallons per minute divided by 490. All right, that gives us a number plus 130 is going to give us 161.7, which is what we're looking for, right? And Rick, you had an even simpler way that you texted me just a bit ago. Well, I can just simplify it like this. Think about the boiler doing nothing but boosting the return temperature. So whatever Delta T we used in the boiler sizing, which we didn't go into those details. So think about this. John came up with a boiler Delta T of around 31 degrees. So we got 130 coming back. He used one, he used 31 in his Delta T. That gives us 161. It's, it's that simple. So yeah, pretty close. Pretty close enough. Yeah. Yeah. And a lot of times when you, when you start going through this, they'll tell the boiler manufacturer will tell you the Delta T that you're designing for based on the flow rate. So you've got the flow rate through the boiler at a certain Delta T. So you simplify this even further. Look in the book. Here's the boiler flow rate at this Delta T. What water temperatures coming back? The Delta T, two about a bing, bada boom, we got a boiler supply temperature, right? So it can get pretty simple. Let me, let me blow something out there. Just because not all boilers are the same and all the features are the same. Some of the boiler manufacturers actually give you a system sensor that you can add. And so it kind of says, okay, we'll always know what the boiler supply temperature is, but we also know what that mix temperature is on the secondary side out there. So they'll get, they'll, they'll pump their, the water temperature up to meet that. So they'll do it for you in some cases. So check with your boiler manufacturer whether that's available or not. Very good. Very good. If we still use 500 for the constant, are we going to be reasonably close? Yeah, the difference between 500 and 490 is simply 500 represents the density of the water at room temperature, at 60 degrees. And 490 represents the density of the water at what temperature, Rick? 100? Somewhere around 140, 150? 140 was a slight reduction. Yeah. Right, right. Very good. Very good. All right. Excellent. So with that, I'm going to turn it over to Rick to discuss boiler pump sizing. All right. So I'm gonna change my present to here and turn this over to Rick Mayo. Do I have it? To okay. All right, let's pull this side. Tell me you see that? Can you see my screen? Already show my screen. There it is. There you go. Put it in all the way and then get rid of that for a second and blow this up. And we should be good to go. Okay. All right. Every, everyone, thanks. Mod-con boiler circulator sizing in a primary secondary piping configuration. This is really about getting the boiler's efficiency where it should be. Okay? So you got, you'll see some little things that happen often within piping in a primary secondary configuration that we're going to try to avoid. We're just going to do our best. There's, there's times where some of the things I'm going to talk about are happen regardless. So we're gonna, you know, give you some examples of how to kind of sharpen your pencil a little bit, make it a little bit better. So John's pretty much pointed this out already. Here's a picture. Okay, we're talking about primary secondary configuration. We'll get into some of these notes as well. John's mentioned some of that. And we're talking specifically about this circulator. In, in the day, I shouldn't say days of old, but when we first started getting into primary secondary, people were piping like this. This is what I will refer to as a boiler loop configuration where if we go back, this is somewhat injecting the boiler into the secondary portion of the system. So just, just to understand those two differences. What we're gonna talk about today would apply to both of sizing of this boiler circulator. One here as its depicted. Okay, it'll, it'll make sense to when I start talking about the A's and the B's and the C's and all that stuff. So alright. So here's some options that are out there nowadays. Okay, some boiler manufacturers actually have a control signal that goes out to the boiler circulator. Okay, it has the ability not just to power it, but to send it a control signal somewhere in a neighborhood of 0 to 10 volts DC. Some have used this thing called pulse width modulation. But let me just clarify what kind of control signal this is. Remember when you were, well, you don't even have to be a kid, I still do it when I'm checking 9-volt batteries, folks. You put your tongue on it and you kind of know whether you get zapped good if it's still strong or if you hardly get zapped at all or you're, you know, then you know it's weak. That's the voltage we're talking about. Zero to 10 volts DC. And that's a typical signal that the boiler manufacturer can send out to the circulator to control it. And it's somewhat of a linear thing. You know, around two, sometimes two and a half, somewhere around there, that pump wakes up and says, "Okay, you want me to do something." And then as it increases the, that voltage, it takes it from whatever that minimum is up to percent, which is close to 10 volts. So understand now the boiler manufacturer has control of the speed of that circulator. And the majority of the ones that I know are gonna base that signal on, guess what? Temperature differential, folks. Whatever the boiler is seeing across its internal heat exchanger. You have the ability to set that Delta T up. And what we'll do is we'll spin the pump in order to maintain a Delta T that's appropriate for that particular boiler. Okay, again, the boiler manufacturer now has control of that circulator. It's like us as a pump manufacturer handing the keys over to the boiler manufacturer and letting them run with it. Okay, now I say that to start with. Now let me clarify something. Not all circulators have the ability to receive that signal. Okay? And not all boilers have the ability to send that signal. So those two things absolutely have to jive in order for this to work. So what we're gonna do is say, since not everybody has it, you should still know how to size the circulator for maximum flow during a design condition. And that's what we're gonna focus on quite a bit here. Okay, hopefully it all makes sense. Should I stop for any questions so far? No, I think you've got it covered. Okay, thanks.

So let's get into this whole near boiler piping of the mod-con boiler and specifically talking about primary secondary. What does it do for us, right? Well, ideally, we're trying to keep the two pumps from ever affecting one another. Some people say fighting, you know, or, you know, uh, you know, just think about it. I don't want the boiler primary circulator to ever affect or do anything to what the system circulator is doing. And if we follow the A's then the B's of primary secondary, we won't have that problem. Okay? The other thing is that as John mentioned before, some of the boilers' heat exchangers, especially when they first came out, had a high pressure drop. Okay? If they have a high pressure drop, then we won't want the system circulator to have to worry about overcoming that additional pressure drop. So when we, when we hydraulically separate the two sides, now the system circulator doesn't have to worry about the boiler's pressure drop. Now, as mentioned before, the boiler manufacturer may control the speed of that primary circulator or not. Okay, that gives you some options out there. Now, we always have to consider short cycling the heated water, right? And I've got, I've got some good pictures that kind of illustrate that, I think, and it'll bring that home. And, and it's something that, as mentioned, when I first started, that we might not be able to control all the time, a hundred percent of the time, but we should keep it to a minimum. And I'll point that out as we get there. Okay, as, as we referred to already, look at the boiler's manual. The manual will show you how they want it piped. And the majority of the residential boiler manufacturers will show these boilers in a primary secondary piped configuration. And some of them will show you alternate piping configurations. We're gonna focus today specifically on primary secondary. Again.

So here's a picture and here's the simple ABCs. Okay, let's get into that. What is, you saw some notes on some of those sketches I had already. Let's, let's cover this and make sure you, you feel comfortable about what this is all about. And we call this just the primary secondary rules. If you follow these rules, you'll never have a problem with with the circulators messing each other up. As I mentioned earlier, these are real simple to kind of memorize. I want to give you some rules and some some actual numbers, but I'll also give you some concepts because for me, concepts will last longer in my mind than memorizing a bunch of numbers and rules and stuff. So again, we'll try to do it both ways. To start with the A rule. Okay, again, the maximum of the distance between the two tees. I'm talkin' right here, is four of the pipe diameters of this secondary header. If this was two inches, then I absolutely don't want to be any more than what? Two, four, six, eight inches. Okay? So that kind of helps you understand that. But with a concept that'll help you up, is if you could still see my picture, I didn't turn my camera off, so I think you can. Everybody that's watching, put this hand up with a thumbs up like I'm showing you there on the screen. And put this hand up like this. And put your hands together like this. And let's call this one a tee. And let's call this one a tee. Put those things. Or let's say it this way. Butt those tees together as close as you possibly can. That's reasonable for making a good connection between the two. Okay? And so if you get this thing as a concept in your mind, you don't ever have to worry about the spacing between the tees. This, here's the concept. Get them together. And you got one tee here and one tee here. The other thing, keep that in mind. Okay, let's get into the note B. Okay, the minimum piping coming in from this side. Notice the flows going this direction, coming in this direction. I want a minimum of eight pipe diameters. Right? I want it eight pipe diameters. And I'll get into this in a second. And I'll explain what I mean by that. I want this flow to be nice and mellow, so to speak, okay, when it approaches this first tee. We've already explained the reason why these are butted together. We don't want a pressure drop between the two. If they're close enough together, there's no appreciable amount of pressure drop between the two. And you're never going to induce flow on one side or the other. But ideally, we want the water as it comes up to this first tee to be somewhat mellowed out. And I'll show you what I mean by that second. Now, once we've already achieved that, that flow pattern, right? Then we're, it's pretty easy to maintain. So with downstream on the on this B portion, downstream of the second tee, it only needs to be four pipe diameters. So eight coming in, but four downstream of it. Again, if I put my hands together like this, look at what I'm doing. Ideally, and the concept is again, I've given you the rules on the screen. The conceptual ideas that I have to tease butted together in the middle of a long piece of pipe. Notice I have a nice long run before the first tee, before you get to any elbows or valves or fittings or anything, right? Nice long coming in. And then I have a nice long distance going out. And the longer the better. Okay, understand what we're saying when we say maximums and minimums. Okay, so get your head around that. The C note has to do with thermal traffic. And I'll cover that on the next slide. And so again, but the tees together, maximum four pipe diameters. Then you got your eight and fours there on your B note. And then as much as you can get on that drop as a minimum, typically it's 18 inches. When I first saw this, it was 12 inches. But that's in the early 90s. So again, the more the better. Just keep that in mind for the thermal trapping. All we're doing with the C note is making sure that the water that's hotter stays up there. The density tells us the hotter water is going to stay up and won't tend to migrate down vertically. Okay, so just, it mostly applied back in the days when, when I was doing this more to variable speed injection mixing legs or bridges. Okay, we wanted that thermal drop so we wouldn't induce any higher temperature in the secondary portion of the system. But let's just rate a couple of things for you. If I'm coming out of this circulator and I'm going across this check valve, this ball valve, as I'm coming out of here, I've got some flow pattern that's would be somewhat like this plug flow pattern or just think of it kind of radical flow, right? You know, it's all radical and it hasn't had time to mellow out. As this illustration shows with this long bullet flow, some people would say that this was laminar flow, right? And it doesn't really equate to what we would technically refer to as laminar flow. But understand, it does mellow out. It goes from this to this flow pattern in a certain amount of straight pipe. And the more the better. That's why we give you the eight pipe diameters. If you could get ten or twelve, by all means, get more than you can. Again, keep in mind what we mean by maximums and minimums and try to always exceed those. But again, hopefully that gives you an idea of what we're trying to do, why we're accomplishing that, why we want those nice long straight pipe links before and after those tees, etc.

So any questions on that while I'm moving into just some review on pipe sizing? No, I think you've got it covered. Okay, again, yeah, folks out there, if you have any questions, please make sure to just chime on in. Just understand, yeah, I can't see those questions, so I'm, I'm relying on my men there. You go. What we're here for. One just came in. Is your C measurement to the circulator or to the 90? It's in the C measurement was referring mostly to the variable speed injection mixing. So it would have been to that first tee to tee. So if I'm coming off a horizontal running, I'm dropping down, elbowing into a secondary portion, I'd want that distance from the hotter water to where we would be injecting into the secondary portion of the system. Hopefully that answered that question. Okay, yeah, C was talking about, yeah, for variable speed injection mixing, kind of a little different animal here. This thing from Tom Albright. Shouldn't the primary circulator pump? Any air separator be on the outlet side of the boiler? On my drawing here, I don't have a boiler that show in there. Right? It's on the secondary. In this case, this could be the hot side. And it is indicated, right? So I, these notes apply to either way. Remember when I showed you the boiler injecting into the secondary or the boiler being a loop? Okay, so this would just say this is the hotter water. Okay, in this case. So let's say this is the boiler side. Okay, very good. And one last one from Bill Chanel, our Channel. What happens if we don't get the eight inches into closely spaced tees? And what happens if you don't have the four inches out? Do you tend to induce flow on those legs? So you could, you know, overshoot temperatures? Well, it's not the end of the world, though. The house is not gonna burn down or anything. But again, that's, we want the flow to be nice and mellow when it reaches those tees. If it's, if it's not, then that first tee will have a slightly higher pressure than the second tee. And you'll tend to induce flow when you don't want to do. Really, the only time you should have flow is when the boiler circulator is on. If we're talking about the boiler specifically. Very good. All right. Excellent.

Okay, in our world of pipe sizing, we have a couple of maximums that we live by. And when you hear us using this terminology all the time, okay, so one of them is four foot of head per hundred foot. We use that in some calculations. You ever sat through any Taco trainings? You hear us talking about that as well. That's one of the maximums that that we use in our industry. Another one of the maximums that we use in our industry is four feet per second. This is a speed limit. This is a pressure drop limit. Okay, understand both of them are good. You can use either one of them. Just give you a couple of things to think about. Okay, if we're talking about these, we have to understand which pipe and size and type that we're talking about. In this example that I'm using to teach off of is specifically for type L coppers. We'll keep that in mind. It changes to from PEX, you know, as far as the GPMs and such. If you're using polypropylene, etc. Type in gives you a little fudge factor here. So just understand you've got to know what pipe and type we're, we're talking about to establish what these maximums are. Okay, so one thing I want you to know, look down this column here and look down this column here. And tell me which one affords you higher flows. And better yet, at what pipe size do they flip-flop? Go ahead and send us some answers. Which ones afford you higher flows? And at what pipe size do they flip-flop? Who, there's a good question. All right, all righty. What are we getting? We're getting some answers. We get speed limit and two inch. Two inch flip-flop. All right, okay. So, yeah, notice what we're saying here. Residentially, if we're gonna use the four feet per second, which a lot of people talk about, right? Then it affords us more flow. Notice this column is higher than this column up to that point. Now, if we use four feet ahead, 400 foot, that starts here. And this becomes higher than this. So they had exactly correct on your answer. Two inches where they flip-flop. I'm just say this, and this is how I've been teaching it for a long time. Use whichever one is most appropriate for your application. Okay, again, one quick example. Had a guy one time say, "Wow, I'm looking for some five-inch pipe because I got a boiler header that that's, you know, relatively short. It's only 30 foot." And he was one, you know, he didn't want to exceed the 149 GPM. He was up at around two million BTUs and he needed 200 gallons a minute. I said, "You don't need five-inch pipe. If it's a relatively short run, you, you're fine." ASHRAE will typically talk about four foot a.

head per hundred foot a pipe all day long. okay. this was a small commercial project and by all means no one would ever argue that ASHRAE said he couldn't do that. he could go up to 270. see, that's what I'm saying. use this, you know, understand both maximum columns and then use the one that's, that's best suited for you. that gives you the highest flow and keeps you within range. okay.

here's another. yeah, go ahead. this was said. wanted to clarify something. rich McGrath brought up about the, just a terminology when, when I was talking about primary and secondary circulators and when you're talking about primary and secondary circulators, so much of it depends on your point of view. personally, when I'm, you, you've got your system circulator which distributes the water to the heating system and then you got your boiler circulator which, you know, circulates through the boiler. now, as long as you know which ones which, you can call whichever one you want primary and whichever one you want secondary. agreed. we just understand we've got the boiler circulator and the system or delivery circulator. okay. and the questions that make sure things are clear. better. yeah, yeah. when I said, when I say primary circulator, I'm usually talking about the system, but that's just me. so, yeah, I'm gonna call him circulator and boiler circulator. here's what I use to determine that. I say, what is the source? are we in a heating system? then the source is the boiler. anything on the boiler piping is primary. okay. anything, especially when we're talking to, did you know, when we inject in out of the boiler up or in to the secondary portion of the system. okay. and then anything that was downstream, like I showed on, when one slide, you know, if that was downstream of something that had already be injected too, that would be the third part or the tertiary. you know, you like the sound of that, right? the, so you got primary, secondary, tertiary, quaternary, you know, it goes on and on. but in my view and what I'm teaching, it just, so I'm not saying I'm right, I'm just saying that I'm making sure everybody knows what I mean when I say it. the, it's, it's whatever the source is. if I'm doing chillers, okay, and I'm piping into the chillers into the secondary portion of the system, then the chiller is the primary portion of the system. so anyway, that's, that's how I teach it. so that's what I'm sticking to. I'm not saying I'm right and everybody's wrong. I'm just saying, hey, just so we're on the same page. you're definitely not saying I'm wrong, right? never. good. that's my gosh. you know, I got, got the delicate gloves on there. so anyway, okay, ready. this is the same thing, but a little different. this is just a couple of columns. one of them is where to use the min/max flows, right? we're gonna stay with the residential kind of realm of, you know, two feet per second. remember why we want to do that and never exceed four feet per second. so all this is is a quick look up to say, for instance, one-inch pipe, you know, if I'm around five GPM up to 10 GPM, I'm golden. and anything in between there, just shows you if the sweet spot. okay. okay. it's, it's a throw. it's not throwing it out, but it's, it's this chart is not showing the four of feet ahead per hundred foot of pipe. it's just doing the speed limits, right? keep it at or above two feet per second and don't exceed four feet per second. so.

and the other thing that I did here is just show you some, some Delta T's, right? I'm showing you, say, hey, if I took that one-inch pipe and I ran ten gallons a minute through it, what could that give me at a 20 degree? well, that's right at a hundred thousand. right? if I went to a thirty, that's that, right? right at one fifty. you know, if I went to stretch it out to a forty, look at what it would, to, who, close to two hundred thousand BTUs. so this just gives you a glance. I will, you know, if I take the time to put a note on something, take the time to read it all. all we mean here in a nutshell is these are maximums, okay? and when you take everything to the max, you lose all of your safety factor. okay? so again, be very careful. and you should always figure out what the pressure drop is gonna be at those given flows and sizes before you select that pipe size. often here is where you go up a pipe size to reduce that overall pressure differential. alright.

so here's what we want you to know. know what the pressure drop is of the boiler's heat exchanger. and some of you can giggle when I give you that acronym, okay? so we, we need to look and see what the boiler manufacturer says because we would, what we're trying to not do is oversize that boiler primary circulator. okay? we want to make sure that doesn't happen. so let's look at what happens. I'm gonna focus on this part of the, the primary secondary configuration and kind of blow that up to you and show you some see-through teas, so to speak. okay? so ideally, we'll want the flow pattern to give us the coolest water back to the boiler's heat exchanger. as this is showing, right? this is going back to the boiler. it's the coolest. it's whatever the return temperature is. the return temperature, okay? and we're trying to get that temperature to, to be as cool as possible going back. we heat it up, we blend back in here, and we go out to the system. so this is the ideal flow pattern in a primary secondary pipe configuration. so we give you the right hand of fellowship with a thumbs up on that, okay? that's what, that's kind of what we're trying to do.

now, this is out there. I mean, I, I call this an acceptable flow pattern. I've had people argue this with me and say, no, that's the only way to do it. well, okay. well, let, let me ask you a question. how you going to accomplish that, right? here's the left hand thumbs up. okay? here's the problem with this. think about it. okay? if I were to have flow patterns like this, and you knew there's two circulators involved in this, we have a system circulator out here, we have a boiler circulator here or here, guess what? what's the likelihood of getting those to be exactly the same GPM? okay? think about it. but for the sake of time, I won't elaborate any more than that, okay? it's really hard to do, kind of impractical. okay? here's what happens, folks, when you oversize the boiler circulator, right? you start getting this heated water coming back across the top. remember, the flow is going from, in my screen, from right to left, but you actually get some crossover here, and you get some blending, and you're actually starting to warm the return temperature back to that modulating condensing piece of equipment, and that's kind of a no-no, right? that's a thumbs down on that one. so understand, this will happen somewhat throughout the season when we had those shoulder conditions, you know, those bench days, that, that we're just not, you can't go any lower than low. and that, that speaks to two things, low fire and low speed on the circulators. so there's times where you're going to get a little bit of this one way or another. what we're trying to do in this little segment is minimize that for, you know, to the least amount, okay?

so let's go in here. here's something that we get from HTP, folks. what did I say? look at the man. you'll look and see what kind of range they give you. how wide will they let you go? that's what I want you to focus on. okay? there's no reason to run it at these tight Delta T's. and the boiler manufacturer now gives you a license. just stretch that delta t. outlets. we're going to stay consistent with a boiler size that's in around a hundred and fifty BTUs, okay? a hundred fifty-five thousand in this case, okay? 104, five thousand. here's what they want at a twenty degree. K gives you the flow rate, right? and it gives you what they anticipate the friction loss to be. at a twenty-five, they tell you what the flow rate is, etcetera. there's a thirty. okay? I'm gonna, you know, I'm gonna try to use on this particular boiler, I'm gonna max it out. I'm gonna use that, and I'm gonna use this, okay? and that's will help in that whole short cycling of the heated water. let's show you what it looks like if I were to take this and blow this up. I want to identify right here that the 155 is this, and I'll blow that up so you could see it. so if I go here, there's the GPM it listed on the last slide, and that's gonna be my operating point at a thirty degree Delta. look at the pressure drop over here, folks. see the head loss? okay? let's go ahead and throw the other ones in there for giggles. okay? so that, there would be in a twenty. but look, group those together. still not a lot of resistance through those heat exchangers. okay?

now, the heat exchangers that this is showing is the, the fire tube style. okay? here's one from Lochinvar. right? same thing. they got a 155. let's highlight that. and again, if I was gonna look at a twenty, that tells me what I need. 25 tells me what I need. 35, that tells me what I need. okay? also, with this particular manufacturer, on this same chart, others put at different places in the manual and such, but since this was all together, I threw it all up on the same slide. maximum flow for that heat exchanger and minimum flow at two listings, high fire and low fire. pay attention to that. if the manufacturer feels it's important to put it in the manual, pay attention to it. okay? so let's look at, see what that looks like on a graph like this, okay? so there's our thirty-five degree Delta. there's our twenty. right? twenty-five, in this case, twenty. okay? so just understand what, what we're showing you here. again, look at these numbers over here, okay? if you're going to be in and around here, you, you're getting a better idea where we're going with this thing. just for the sake of time, I'm gonna move on a little quicker. right? there's another brand. there's NTI, showing you a twenty, showing you a 25, showing you a thirty, etcetera. you see where we're going with this. let's go ahead and plot it. okay? this will give you an idea how to look at these boilers manuals, how you can interpret and do exactly what they're doing and prove why they're doing what they're asking you to do, okay? so it gives you a better idea and a better concept of why we're looking at this a little closer.

here's one from Weil-McLain. okay? same thing, right? there's our 155. there's a 20, a 30, and even a 40. okay? that there. okay? and again, if you want to do something different than the boiler manufacturer has in their manual, you better get it in writing from them that it's okay. and many of them will. they just, at the time they printed the manuals, they did that, and they might have, they might have an update, they might have a bulletin that gives you more. okay? same thing here. I'm just plotting this stuff out. there's the 40, there's the 30, and there's the 20. but here's one thing I will make note of. some of the manufacturers, so always note what they're talking about down here. in this case, we're having the pressure drop that's associated with flow through the heat exchanger and some incidental near boiler piping. so you'll have to find out from, in this case, from Weil-McLain, what they added in there. so you don't want to double dip. okay? if, double dipping, you know what I mean by that? so, okay.

one question here from Bill. so you're suggesting we design the boiler loop pump to a 25 or 30 degree Delta T, assuming no speed control from the boiler? I'm believing, I believe you're suggesting that you can, based on the manufacturer's instructions. I'm, that's what I'm stating. the manufacturer is giving you the license by, see, by, by putting in that, that manual, what those Delta T and GPM requirements are. and yes, I, I want to point out, if the boiler has the output control signal and the circulator is small enough, I'm emphasizing that for a reason, if the circulator is small enough and has the ability to receive that control signal, then by all means, use it. okay? but in some cases, in fact, many cases, one of those things are missing. so that's why we're spending so much time talking about how to size that circulator under a fixed speed application. does that make sense? yep.

and Bill follows up by saying that would improve performance at low BTU situations. well, it's just gonna give you a less of the crossover where we're actually sending the heated water back. now, low situations are gonna be those shoulder conditions that I mentioned earlier, and you're gonna get some of that at times. it's when we get up into the heating season and we actually need the boiler to do what it's doing, you're gonna get lower return temperatures back to the boiler under those conditions. that's what we're trying to make better. okay? very good.

all right, so let's just do a quick example. let's go through and, and, and again, we've already shown you the boiler manufacturer gives you the GPM and all that stuff. let's show you how they're coming up with that, okay? take the input of the boiler, okay? we need to deduct because boilers aren't quite 100% efficient, right? so we need to deduct for efficiency based on the application. and I'll, I'll get into that and I'll talk about what that means. and we also sometimes we have to de-rate for altitude. some people look at it strictly from the standpoint of what is the caloric value of the natural gas from that utility at that altitude, and you can get that information from the utility, okay? so for instance, Denver, right? they, if you to find out what their gas is giving you at 5,000 foot, it's in the neighborhood of about a 16% deduct. so understand that you're sizing the boiler circulator on what the capacity the boiler is under the job specific condition. so you have to kind of know, you know, what's going on. basically, it's this: take the input of the boiler minus this efficiency and any additional like altitudes or caloric values, and that'll tell you what the boiler is gonna do.

here's, here's one, one thing I want to propose as a question and give me a little feedback if you would. how many people think that the mod con boiler goes to high fire and how often? to kind of a two-part question. give me some feedback, guys. all right, guys, type in your, type in your, your thoughts on that one. here's something to think about while you're, while you're typing that in. what tells the boiler to go to high fire? do you think a switch tells the boiler go to high fire? do you think a DHW call tells the boiler go to high fire? I want you to really think about that. so what I get here is almost never. not often. should only be during the designed a high fire on the coldest day and DHW calls. but perfect. all those, all those are good. rarely. maybe two or three, two to three percent of the time. and only, and only if the boiler is exactly the right size. now, John, what if you always tell people about picking the boiler size or idea wingers when the door baby, you need two other guys to help you get it in there, then that's what you're gonna have to do. but you want the biggest boiler that will fit through that door. yeah. well, we taught it better now. here's what happens though. most people say, well, that's, you know, I, you know, that one's too small, so I'm gonna go, this one's, yeah, it's bigger than I need, but you see what I'm saying? that bigger than I need, but that's the one that, that, and they all turned down. now people use that as an excuse, right? so what we're saying is the boiler might never go to high fire. so you have to use that as part of the thing you use in the boiler circulator sizing anyway.

so here it is, and I'll go quicker. I'm running out of time, folks. let's use that same boiler at 1:55. let's say it's gonna run at an AFUE listing of 95%, so we'll take 5% off of it. we're using, in this case, a 30-degree Delta T. many of those boilers said you could do that, right? I'm not doing anything strange. my 490, folks, is just John's already explained that to you. put 500 in there if you feel more comfortable with that. it's just that the hotter the water is, the less dense it is, right? so you were accounting for that. so 30 times 490 is 14.7. if we do 147 to 50 divided by this number, it tells us what the GPM is. and again, we're in seminar land, we're at 10 gallons a minute, okay?

so here's the same input of the boiler. and notice, if I'm not running that boiler in a condensing application very often, I have to use a lower number. okay? so do you site the pump accordingly? in this case, it's 133.3. same math here. I only need 9 gallons a minute. okay? so understand that. here's the problem. most people, and a lot of people just said, you don't want, I'm gonna put a 15 gallon um in a pump on that boiler because it's a hundred fifty-five thousand. okay? you see what what happens there? so we'll gonna actually show ya, right? so here's the folks that have to worry about altitude. well, first thing we do is we deduct for altitude. in this case, there's your 16% for Denver. right? now we only have a boiler sitting on the job that's 130,200. okay? it's not a 155 anymore. okay? so let's use that number in your calculation. take off your efficiency. it's not 100% efficient. and so now, now we do that same calculations. look, we only need a little over 8 gallons a minute to do that 155,000 BTU input boiler. okay? and for the sake of time, I'm doing the same thing at a reduced amount of efficiency. up here, I have 0.95. here's a 1. that's right on the edge of condensing. look, you know, I, I only need seven and a half gallons a minute to do that boiler under these design conditions. so why do you think people when they're throwing fifteen gallon a minute pumps on their are getting lesser boiler efficiency? so just something to, you know, to think about. and we'll wrap it up with this. okay?

so the, in a piping configuration, if we were going to use 10 gallons a minute in our load, we, and at the boiler manufacturer's information, you have figured out the heat exchanger is going to be two-foot. we figured out that, you know, based on calculations through the near boiler piping incidentals and such, we had anywhere from like one foot to a three foot. let's go ahead and, in this case, just call it five foot. so I need 10 gallons a minute at five foot ahead. so we got double O a teeny. we're going to show you this for a specific reason, right? this circulator, and the fixed speed mode, has the ability to adjust it to anything you want. I emphasize fixed speed mode, okay? again, we're talking about a situation where I don't have an external control for the speed of the pump. okay? we just want to get it set up right and let the pump spin when there's a call. okay? so understand that we have this bin max in this particular circulator. we can go as low as four watts or as high as forty-four watts, and more importantly, anything in between. okay? so here's what that looks like with that whole area shaded in. let's do our 10 gallons a minute here. we'll do our five feet of head there. at that, because my operating point, that's what we anticipated the, the system resistance to be. so there's my system curve for that boiler circuitry, and there's my operating point. okay? the, the great thing about this is I have room to move it up if I need to, and I have room to move it down if I need to. on the double-o a teeny or any of the Taco circulators that give you that min max setting, it's a beautiful thing, folks, who really, folks that want to get it these things dialed in correctly. okay?

here's, for instance, that doesn't have the men backs. but let's see what happens here. here's our double O 15 III. okay? it's a similar curve. okay? it's got a constant pressure of 5 foot, constant pressure of 10 foot, and we've got maximum speed. John's proverbial contractor no callback mode. okay? so let's go ahead and plot it on this one as well. there's 10 gallons a minute, 5 foot ahead. there's my resistance of that boiler circuitry and heat exchanger, and they, my operating point. now, if I blow it a little bit, this, this can move out this direction or can move out this direction. on the initial start up, again, there's not anything in that circuitry that's gonna have this thing automatically moving. but it's gonna find this little happy spot right in and around here somewhere. okay? again, if you over anticipated what your resistance was, then you'll be able to reach your, your 10 GPM might go out this way a little bit, and vice versa, a little bit. so, all right.

so wrapping it up with this. so as the load changes, right? so here's, here's what we came up here. here was our calculation, right? so that's if I need 147, 250. let's take half of that load, okay? let's just cut the boiler in half. okay? we're on a half load condition, and we're down to 73. if I use the same calculation, now what I'm doing is I'm flip-flop in these numbers. here's my constant, okay? here's my new load, and I already know the pump's at a fixed speed, so I lock that into my calculation at 10 GPM. it's gonna tell me what, what, what am I solving for right here? the new delta T. so, hey, I'm not at a 30 anymore. notice that's a linear thing. if I was at a 30 and I took the boiler and I cut it in half, well, my Delta T's gonna drop in a half as well. and so on and so forth as we get into those lighter conditions. okay? are we gonna get a little crossover at the T's? you got it. but what if my point is, and I hope I've made it, is keep that initial GPM as low as possible on that boiler circulator. wind pipe primary/secondary. so from there, I'm batting it back to Barbra.

all righty, very well done. excellent. there's a lot of good stuff here. now, guys, we're gonna take your questions for another five minutes or so. we do appreciate, do appreciate all that. so terrific. here's a question just came in from Nicholas in regards to heat migration off of CS TS, I'm guess that means closely spaced T's. is it preferred to the branches of the Tees branch down below the header with an 18 inch drop, or is it okay to have them branch up directly above the header? so in terms of heat my toe, that's, yeah, you know what? again, if the boiler, if the system circulator is on the boy and is calling for heat, and the, the control pulls in the TT's of the boiler, that boiler circulator is gonna be on anyway, and so it's, we're not worried about migration anymore. okay? based on the way I understood the question, that's my answer.

all right, very good. any more questions, folks? please, please type them in. now is to be a good, good opportunity to do that. let's see what we have. boom, boom, boom. okay. did, anyway, there was one here. let's like it a short cycle. then one more. here's one. the graphs you were showing assumes constant speed pumping and constant firing rate, correct? that was from Joseph. massive, massive Ani. oh, I'm sorry. Mason Avi. there we go. got you, Joseph. but I think we, I think we do. I think Rick addressed that later on. Joseph, please type that in if, if we're, if that question got answered for you when Rick did some changes there. so that's a good question. want to make it. I think we addressed that one. will a buffer tank prevent the crossover condition from happening? my thought is, not necessarily. not if you oversized that boiler pump. not necessarily. it might mitigate it a little, but, but it's still gonna have that pressure. you, you, your decoupling still, but I think they're still gonna be, you're not gonna impact flow on the delivery side, but you'll still have that crossover on the, on the boiler side. it, depending on what that boiler flow is. the one thing about having all that mass and stratification within a buffer tank is that the return temperature going to that boy, there's gonna be whatever sitting at the bottom of that buffer tank, at least initially. and again, that's not a license to oversize your pump. all right. okay. get the pump sizing right. you know, you've got enough information from the manufacturer, the boiler, as well as a circulator manufacturer. just let's get it right.

now, let's keep our pencil sharp. absolutely. and playing the benefits, obviously, the benefits of doing that. it's always better to do the math than not, because when you do the math, you know. and if you don't do the math, you're guessing. and when you're guessing, one of three things can happen, and two of them aren't good. I mean, you could guess dead-on accurate every single time, and then that means you are the chosen one, or you could guess low, and that's not good, or you could guess high, and that's not good. so the odds are not in your favor when you guess or go by hunch or experience. keep the pencil sharp. there you go. that's it. all your excellent. it's always good advice. that's right. very good. very good.

all righty, folks, last round up for questions. I do appreciate the gift of your time, folks, on this beautiful Tuesday morning, our afternoon, wherever you are. awesome job, Rick. Dave, thanks. great job answering those questions on the, you know, behind that, behind the scene. thank you for that. problem. and again, we're looking forward to this. we'll do another one in a, another, we have another one next week on the commercial side, and then one more after that. and then, and after June, we're gonna go back to our every other week format. throughout the Cova 19 quarantine, we decided to do one of these every week for the benefit of folks that are stuck at home. but now people are getting out, they're going back to work, things are loosening up a little bit, which is a good thing. so thank goodness. so we'll be doing, we're going back in July, starting in July, every other week for Taco Tuesday. so we do appreciate your, your, your continued attendance throughout this, and we, throughout the, the, the quarantine and lock downs and things. and we look forward to seeing you again next week, and the week after, and then every other week following July. so thank you all. always a pleasure. Jim DePalma. absolutely. Jeff, thank you. Mr. McGrath, it's always, it's always an honor. come when you, when you come to join us. I really appreciate it. Richard. alrighty, thank you all, folks, and have yourself a fantastic Tuesday and a great rest of the week. and take care. thank you all. you. you.