Andrea on Understanding Total Dynamic Head and Valve Management in Pools

Andrea discusses the intricacies of pool circulation systems, focusing on total dynamic head, valves, piping, and the importance of proper maintenance to ensure safe and efficient pool operation.

keywords

pool circulation, total dynamic head, pool valves, water flow, pool maintenance, water hammer, filtration, pool system design

key topics

• Total dynamic head calculation and importance
• Types of pool valves and their functions
• Risks of water hammer and how to prevent it

guest name

• Understanding Total Dynamic Head and Valve Management in Pools

Sound Bites

• "Variable speed motors optimize energy use"
• "Gate valves should be fully open or closed"
• "Water hammer can cause pipe damage"

Chapters

00:00
Introduction and Technical Difficulties

02:48
Understanding Total Dynamic Head (TDH)

06:05
The Importance of Valves in Pool Systems

10:53
Piping and Flow Dynamics

14:53
Filters, Heaters, and Separation Tanks

20:31
The Heart of Pool Maintenance: Circulation

Resources

• Blu-ray XL
• revvedupto.com
• Talking Pools Podcast

Transcript

SPEAKER_00 0:53

Well, hello. That took a lot of time for me to figure out. What was I doing? I was trying to fix my camera from overexposing and actually, well, it wasn't overexposing, it was darkening my face. So every time I came into the frame, my camera would darken. And then it looked like I was sitting in shadow, even though I have this bright, bright light shining directly at my face. So why should I sit here and be uncomfortable if it's not even gonna work? Sorry for rambling. Hi everyone. It is the Talking Pools podcast. It's me, it's Andrea, and it's Tuesday. And so I am going to be unfiltered today, as usual. So I hope everyone's had a good week. For me, it's it's exciting and it's also frustrating because every day is a new day for a bunch of snowbirds to go home. Every day is a new car carrier coming down. So anyway, I'm just kidding. Love you guys sometimes. So if you are just tuning in, thank you for being here. It's lovely. I love you. Thank you so much. If I, you know, if you guys don't tune in to listen, I'm just sitting here talking into my microphone and spitting all over it for no reason. So thank you. I really do appreciate it. So let us get into the exciting conclusion of last week's episode. And where did I leave you guys? I left you at Total Dynamic Head. We're not gonna make any jokes, all right, because we're adults and Total Dynamic Head is not funny. It's very serious.

SPEAKER_03 3:03

The Talking Pools Podcast is now accepting nominations for its 2026 Mentor of the Year Award, honoring those who don't just have the answers, but teach others how to find them. If someone helped shape your path in this industry, now is the time to return the favor. Visit cpoclass.com. Click on the Talking Pools Podcast Mentor Award tab, and submit your mentor's name up until May 15th, 2026, because behind every Great Pool professional, there's someone who showed them how to think.

SPEAKER_02 3:35

The 2026 Talking Pools Podcast Mentor of the Year Award is sponsored by Blu-ray XL and Revved Up Apparel. Go to mentoraward.com and tell us who had your six. Again, that's mentoraward.com.

SPEAKER_00 3:55

Okay. What is total dynamic head, you ask? Well, it measures the total resistance to water flow throughout the entire pool system. So every part of the pool system creates some level of flow loss, including the plumbing, the pipe fittings, the filter, the heater, return outlets, or I mean, um, you know, whatever. I can always get them backwards. Everybody does returns, suction outlets, the weird door. Okay, all of this. So calculating the TDH, should I say TDH the whole time, or should I say total dynamic head the whole time? I don't know. We'll see how it goes. Calculating the TDH is essential for selecting the properly sized pump and motor. They actually use this calculation to determine what size pump and motor that is needed for this pool. They're not supposed to wait. So the TDH of any operating system can be determined by using the pump's vacuum and pressure gauge readings to calculate the suction side head. Calm down, everyone. You multiply the vacuum gauge reading by 1.1, calculate the pressure side head, multiply the pressure gauge reading by 2.31. You add these two values together, and that gives you the system's actual operating total dynamic head. Okay. See how many times I can say head in this episode. I've said it a bunch already. That might be the end of it, actually. So now we move on to motors. Pump motors used in pool and spa systems come in a wide range of designs and insulation configurations. Variable speed motors typically run at lower speeds overnight or during lighter use hours in residential pools, such as in the morning or in the evening, and then they shift to higher speeds for shorter periods when increased flow is needed, which I'm sure you already knew, but this is for the new people. Alright, so let's just remember that. You have valves now, these are contributors to TDH. You have to take into account all of these things. The valves are used to control and regulate water flow within the pool and spa circulation systems. There are just one type of valve. Just kidding. There are many types of valves. So you have your date valves, your ball valves, butterfly valves, which are sometimes called wafer valves, you have your multiports, your globe valves, which I have never heard of, and then you have your check valves, which everybody knows. Almost everybody. Your valves may be operated either manually or automatically. You have actuators. Excuse me. Because every valve creates some resistance to water flow, they must always be considered as part of the system's overall engineering design. So, you know, you go changing valves, you're changing someone's head, someone's total dynamic head. Oh shut up. Okay, so this is important. All right, now this is one of those things where I was not really taught, like, like nobody came out and said this to me ever. It was just kind of something that I heard someone say, and then I asked about it more, and I was like, what do you why? What's what is the problem here? So you should always be shutting off the pump when you change valve positions, valve handles. Obviously, we know before removing any fittings or clamps or whatever, blah, blah, blah. We all know that that's under pressure. That's obvious, right? But you want to turn it off when you're changing valves, also, and I will tell you why in a second. So just hang on. If you have that question, write it down so that you don't forget and you can ask me later. Also, just there's a couple of things that nobody ever taught me, and I'll I'll get to the next one in a second. So it's it's a risk if you change the valve handles or change the valve position with the pump on, because this can cause the equipment to quote, separate violently, which may result in severe injury or death. I'll I'll get to that in a second. I'm still talking about valves. We have gate valves. These are designed to either be, this is one of the other things I didn't know until I was doing, until I was gathering facts for this episode. Gate valves are designed to either be fully open or fully closed. They should never be left in a partially open position. And I had wish somebody had told me that many years ago before I was leaving gate valves partially open. Ball valves, everyone's favorite. Ball valves consist of a housing that contains a spherical ball, which actually that is that redundant? That's redundant, right? Because a ball is a sphere and a sphere is a ball. Anyway, it has a circular opening through its center. The handle is connected directly to this ball, or sphere, if you will, allowing it to rotate and control flow. Because they can be fully closed, fully open, or set anywhere in between. Ball valves are considered regulating valves. So your Jandy Neverlubes, your three-way valves, those are technically, well not technically, those are ball valves. At least that's what it said in the book that I read to get this information from. Butterfly valves are more common in my experience, anyway, in commercial pools, much larger pools, more complex multi-filter systems. This internal butterfly plate is connected to the handle and rotates on its axis as the handle is turned, allowing the flow of water to be controlled. Multiport valves, these are on your DE filters and your sand filters. There are two types of multi-port valves. You have a slide valve and the rotary type. The purpose of the multi-port valve is to simplify the system operation by reducing the number of individual valves needed. So the multi-port valves have multiple ports. Some rotary valves include only basic filter and backwash settings, while others are more advanced and offer additional positions such as your bypass, your rinse, your recirculate, and off, apparently. I know there's a waste one. Maybe that's what it meant to say. It is generally recommended to use the rinse cycle between backwash and filter modes to help prevent dirt particles from being trapped in the valve mechanism and returning back to the pool. Me personally, I do a rinse cycle. Rinse it until it uh runs clear and then alternate that a minimum of three times, but I I can I go at OCD sometimes and do it a little bit more than just three. Um then you have the push and pull valves or slime valve. I think some people call them a plunger valve, but I don't I don't think that's accurate because I think a plunger valve is something completely different. So this has a large cylindrical body with inlet and outlet ports, and then inside the cylinder is a movable shaft fitted with wafers. A wafer is like just like a flat disc that redirects the flow of water as the valve is operated. So with those, you usually, if I'm remembering from experience, you usually have to turn the valve and then pull it up. Something you know, something different. You have to like, there's a little metal knob and then you turn it out of its little locking thing. Anyway. Then we have our check valves, which inside there is a spring-loaded mechanism that requires a specific amount of pressure to compress the spring and allow water to flow in one direction, not the band though. The valve then seals to prevent flow in the opposite direction. Next we move on to piping. So if the the pump is the heart of the circulation system, then the suction side piping components are the veins, and your pressure side components are the arteries. So you could make a person out of a pool. Or maybe you could make a person pulled to a person. Every foot or meter of pipe and every fitting, elbow, connection, and T represents a friction loss in the circulation system. The diameter of the pipe and the material used to manufacture the pipe also factor into the head losses. Are you keeping track of how many times I've said head so far? I hope so. The efficiency of water flow is also influenced by water velocity. The speed at which water moves through a pipe is determined by two main factors, the diameter of the pipe and the head pressure produced by the pump. The velocity of water flowing through any pipe is limited by industry standards as well as state and local regulations. Schedule 40, pool recirculation piping must be constructed using at least Schedule 40. Now we have our pressure side elements, and we've already covered filtration and the different types of filters, so I'm not gonna get into that. However, I do want to mention that you must always remain aware. Okay, always be look always be watching. That a is that an actual phrase? I don't know. That sounds familiar. Was that in a movie? Always be I don't know, always be watching. Just always be careful of these systems. A normal byproduct of a centrifugal pump, which if you'll remember from last week, that's the only type of pump that we use on pool systems, is the introduction of air into the system. And this air usually collects at the highest point of the plumbing in the plumbing, and this is usually the filter. This is why we have the air relief valve. Usually the air builds up in the filter, and because air is compressible, it can create dangerous pressure conditions such as violent separation. Like I remember I'm going doing a call back to earlier. So any sudden change in hydraulic flow, such as Miss South Carolina, such as a moving valve, there it is, can cause a water hammer effect that may force system components apart violently. So there's your violent separation, and that is the specific reason why it is important to make sure at least tell your customers to turn the pump off before they change valves if you're not gonna do it. All right. So before, this is why, this is why I said that it's a good idea, okay? I'm not telling you what to do. So let me define water hammer for you, okay? Because if you've not heard that term before, you might be going, UTH. What's the actual hockey pump? What UTH. So according to, I got this definition from a website, DFT Valves, ever heard of them.com. I added the ever heard of them part. The actual website is dft-valve.com. Water hammer or hydraulic shock, also known as aka, is a high pressure shock wave that occurs in piping systems when fluid in motion suddenly stops or changes direction, often caused by abruptly closing a valve or shutting down a pump. This sudden momentum change creates a loud banging noise, potentially causing pipe damage leaks or burst fittings due to pressure spikes that can exceed 10 times the system's normal operating pressure. So if you have ever changed a valve, okay, now I I know that I have experienced this before. Fortunately for me, I have not experienced violent separation of any pool components or pipes or anything like that. And this is why I just wanted to warn everybody, okay? If you've ever heard a loud bang or the whole system shulk, shut the pump off next time you change a valve in that system, okay? Because that is very scary. Now, back to pressure filters, real quick. As the filter collects oils and debris, water flow from the pump begins to decrease. And as this happens, pressure on the influent side of the filter rises while pressure on the effluent side drops. Influent is water coming in, effluent is water going out. Just in case somebody didn't know what I was talking about. Pressure filter media can be easily affected by excessive pressure. Over time, too much force may damage the media or allow water to bypass it, sending unfiltered water back to this reduces overall water quality and increases the need for additional chemicals, which we talked about in the filtration episode. Separation tanks, it's I'm talking about it now because it's all part of the circulation system. So it's not like I'm merging things that don't matter. This is all connected, okay? Separation tanks are used to collect spent DE so the material can be contained and disposed of properly instead of being discharged into your local water systems or just in someone's grass. There's a bag inside the tank, it collects the D. Then you separate the water and it you put the water back in the pool and then you throw away the DE powder. Okay? Case closed. Nobody that I know, they don't have those here anymore. I don't know why. Heaters are contributors to head loss, and they are part of the circulation system. As water moves through the device, it creates hydraulic or friction loss. Heater piping is typically equipped with a bypass line and valve, and this setup allows a controlled amount of water to circulate through the heater to manage the temperature, the heat rise, while also permitting minimal flow through the heater during warmer season. It's for whatever reason, if you need to do a treatment, there's lots of reason for a bypass, right? Flow meters. Mostly only on commercial pools, but I have seen them on residential pools before. It's not like it's a bad idea. You know, more equipment. Um, so like I said, all public pools and spas should be equipped with flow measuring device, uh, with a flow measuring device that shows the rate of water moving through the circulation system. The flow meter typically displays readings in gallons per minute, gallons per minute, or LPM. Now we have automatic monitoring and control systems to manage water level, temperature, lighting, air blowers. Some of them are integrated into the pool circulation system, like ORP systems. So the water comes from the pool and then goes back to the pool, but it's diverted through the thing, through the ORP system, so it is part of the circulation system. This is why you need to get permits to change things like that, because it affects the whole pool. Chemicals may be incorporated into the circulation system using various methods, such as positive displacement pumps, which are your stenners and your rollochens, and your t in your erosion feeders, which are your cab feeders. Once the water has been filtered, chemically treated and brought to the proper temperature, it is returned to the pool. Returns can be on the walls and the floor, or both, a combination of both. So one really fun thing that I have always wanted to do or be present or participate in is a dye test. And I don't mean for leak detection, I don't mean the little syringe with the with the dye with the purple dye in there. Although that is fun, that's not what I'm talking about. So this is a way to visually visualize and you it's a the you put the dye in the thing and then the dye comes out right. Sorry. Verify how effectively the water is circulating throughout the pool, is what I meant to say with a dye test. So the process I'll go through real quick. You turn the pump off, the dye is introduced into the circulation line as close as possible to the usual disinfection point. So they often will take a positive displacement pump, probably a stunner, use that to feed the dye into like where the chlorine goes. Then the circulation pump is turned back on, the main pool pump is turned on as normal. So you get your normal flow. Once the pool reaches a uniform color, say you you can use either a purple dye, it's like crystal violet something. I can't remember, I didn't write it down, and then there's a bright like yellow one that they used on the Skinwalker Ranch show. It's kind of cool because the dye didn't come out the other side. But anyway, who then sorry, once it reaches a uniform color, the disinfectant and the ozone systems, ozone if there is one, but your chlorine disinfectant feeders can be turned back on. The dye will then oxidize, and the disappearance of the color actually serves as a secondary test on the circulation. So the pool should achieve uh uniform color distribution in half of the normal turnover time or less. So I just think it would be really fun to have that, to see that done. To sum up, continuous, well-designed circulation is what distinguishes a swimming pool from a stagnant, stinky pond body of water. Proper circulation prevents algae and pathogen growth. Pathogen growth keeps water safe and enjoyable, and it's fundamental to all other aspects of pool maintenance. Because if you don't have the water moving, if it's not circulating, it doesn't matter what chemicals you put in there. I mean you can hold it off for a while, but it's eventually gonna take over and you're not gonna be able to get it. Well, first of all, you can't do anything with the filter, obviously, but chemicals can only work for so long. So when viewed together, you have pool filtration, you have chemistry, and you have circulation. And these function like the vital organs of the human body for bringing it back. Filtration is the kidneys, which are constantly removing waste and impurities from the water. You have the chemical balance, which serves as the liver, which is neutralizing contaminants and maintaining internal stability. Circulation is the heart, my friends, that is the whole thing. Reason I did this whole entire nine month long series is to prove that circulation is the heart of the system. It keeps the entire thing moving so that the filtration and the chemicals can do their jobs effectively. Only when all three systems work in harmony does a swimming pool remain clean, healthy, and safe, just as a body depends on the coordinated function of its organs to thrive. And that's it. The end. Thank you for listening. Now, maybe next week I'll talk about something else that's not pool. I would never. I could never. Okay. I don't even know about anything that's not pools at all. So yeah, that's it. I really appreciate everyone listening. I know if this is a little bit shorter of an episode, but that's cool with me, right? Again, if you want to email me, you can. It's Andrea.talkingpools at gmail.com. You can email Rudy and the rest of the show at talkingpools at gmail.com. Follow me on all my socials. Okay, there's me, just normal on Facebook, Adventures of the Pool Girl. I actually made a page to post all my episodes, which is called Andrea Unfiltered, which I've only posted one episode so far, but I'll get up on that. And I think I think that's pretty much it. Again, thank you for listening. And I hope everybody has a great rest of the week. And I'll see you next Tuesday.