How to use Static Pressure to Measure and Set Air Flow

hey thanks for watching in this video my friend eric kaiser talks about measuring static pressure and using that along with factory fan charts and fan curves in order to calculate airflow and to learn more about airflow in general eric's one of the best educators in our industry and i'm really thankful that he took the time to share with everybody at the second annual hvacr symposium it was a great time we got to meet so many different people eric wasn't able to be here in person but he did zoom in to the classroom and then there was also a group of attendees virtually really a great session and i wanted to make sure that you got a chance to see it so thank you to eric for allowing us to use this here on the youtube channel again eric kaiser talking about static pressure measurement and airflow charts i hope you enjoy all right folks well welcome to um a another class here that you're sitting in hopefully you guys are learning something down there so my name is eric kaiser coming to you from beautiful indianapolis where it is uh sunny and 60 instead of i hear you guys about sunny in 85 so a little bit different if you have questions going through we're talking about static pressure setting up blower speeds and sizing air filters three things that actually kind of go together so if you have questions while we're going through today feel free to ask those that are online of course can raise your hand and and uh i think can they type in can they uh come in by voice or is it just typing in on the chat oh both okay all right so there we go if you guys online want to ask questions also feel free i'll pop the chat window up here in case i see something jump up i can see that as well so with that who who in the room there uses static pressure you ever measure static pressure i can see you can raise your hand see i can see you raise your hands um right so it's a pretty important thing so let's dig into that first number one what is static pressure okay so static pressure is the force so when they're air in inside ducts when air is moving through ducts we have two pressures we have velocity pressure which is the force of the air coming through the duct and then we have static pressure which is what's pushing outwards on that duct okay and that's created by the velocity pressure pushing through here it pushes out and we use static pressure to figure out how much resistance to air flow we have in that ductwork or in or on a component how much that component resists air flow being flowed through now that applies to when we measure it that applies to that component in that moment of time with that specific volume of air that's moving through it all right typically we use a scale inches of water column or or you might see wg as water gauge is the scale that we use so there's somebody else with a live mic i'm getting a little bit of uh noise through here i'll mute them okay thanks so that's what static pressure is right resistance to airflow when the blower turns on it creates that resistance to airflow we push out the little guy down here is the blower right the air is going to be the box we're trying to move that air and the hill pushing back is the duct work so static pressure obviously changes with air volume going through ducts so when we measure it it's only applicable to the volume of air going through the duct at that point in time or through the component whether it be a filter or a fitting or a grill now external static pressure so external static pressure is anything that's outside of the blower bearing unit so if we have a furnace right where we've got a blower in the bottom right we're pushing up through here that furnace is rated from the top to the bottom anything outside of that or in that case you might put something in the sides of your blower compartment that's external to the unit same thing with an air handler here where we have a negative pressure coil right or if you have you may have a what is it train makes air handlers now that have a positive pressure coil or a fan coil unit that has a positive pressure coil on it i think mitsubishi does as well so you may see it both ways but outside of that whatever we connect to it in the field is what we're measuring the resistance of that's what the blower is capable of overcoming and if we put too much resistance on that that blower may fail prematurely things like that so when we measure it we measure a positive and a negative static all right so positive negative if we hook up a dual port manometer something like this we put the the negative side or the low side of that dual port manometer on the inlet connect to the outlet we get our total external static pressure or external static pressure right there now we can also measure one side and then measure the other side okay and then we add those two numbers together the challenge with this is that a lot of people run into if they're not familiar with it is you don't use these symbols because these symbols here your plus and your minus only mean only indicate which side of the blower you took it on they're not part of the mathematical equation so we get rid of those we just add those two numbers together and we get our external static pressure make a sense okay probably done this before i just want to go over it because i don't know who all is in here or what experience you've had so it's a good thing to remember that because i've seen a lot of people try to oh i've gotta take this and subtract this and then you end up with a really low static pressure and you're chasing your tail around going well why do i have a problem if i've got low static pressure all right now differential static or static drop okay so that's the static pressure on this side you got a component in here like an air filter what's the static differential or delta p as it's sometimes called so if we add 0.23 inches here 0.15 inches here our air is flowing this way we've got a .08 inch drop across that component okay when we make the connection on the manometer we're going to make our positive connection over here even if this is in the return side we're going to make our positive connection on this side if we're using a dual port manometer and our negative port over here because this is lower pressure those two ports are in reference to each other so the higher pressure port goes to the positive lower pressure is going to go to the negative does that make sense okay now what tools do we need of course we need a manometer all kinds of different stuff these are ones that i've used i like them all they all have pluses and minuses when you're talking about magna helix sometimes they get a little iffy to read they are sensitive to things like vibration and dropping stuff like that a lot more than the digital ones are so i don't so much like to use these in the field transport them around in my truck unless i have a good solid way to carry them foam filled case something like that the other thing is on a magna helix if you're using that it has to be perfectly level you actually need to put it on a perfectly level surface in order for it to be accurate so i am a real big fan of digital i used this little 510 for years i've got the the 510i uh the new tec dg8 is a really nice meter because it can do static pressure and building diagnostics it goes you know it goes real low in the pascal scale even so that's a handy thing plugs to be able to plug up the holes that we make in the duct work it's a really handy thing to have you buy a little plastic plugs pretty easily if you deal with truetech tools they sell them we need some good hose i like a nice silicon hose that doesn't keep a memory to it if i can find it because that way when it comes out of my bag i'm not trying to uncoil something and deal with pulling that out straight you can get single port manometers like the field piece now field piece makes these single port bluetooth manometers and then the app combines two of them together and it acts like a dual port so they both connect up to the app and it combines them into the dual port we need static tips of some kind so this is a static tip what's called a static tip and this is another tool that i really like to use which is just a ball inflator needle for inflating soccer balls or footballs or anything like that and the handy thing about that ball inflator needle is it's small enough that it fits through the hole of a screw so when you're trying to measure in really tight locations like between the furnace cabinet and a coil or if you have an air handler with a built-in filter slot you need to measure between those points that ball inflator needle works really well we'll talk about how to test that in a little bit um drill bit i love little step bits like this to go into a a small drill or a screwdriver with a quarter inch hex coupling on the front of it or any small drill that that's a great thing for drilling holes and lastly anytime you choose a manometer you want to choose something that has a minimum of a .01 inch water column resolution to it you know find your accuracy the one that you like but you need that as a minimum resolution for measuring static pressure you know the uh the dg8 will go farther than that but any of these other instruments and there's a lot of other ones out on the market i didn't put them all on here these are just some of my favorites that i like to use all right but that's that's a big thing because i've seen people there used to be several digital manometers on the market that would only go to 0.1 inch and they would try to measure static pressure and i'm like you can't do it because you're missing this other digit over here that tells you where you're at it increases the accuracy of your reading okay now static pressure tip commonly referred to by some people as a pitot tube but this is not actually a pitot tube this is a static tip static tips measure on the side of the tip this tip needs to point into the air stream and then comes back here to a single port a pedo tube is actually going to have two gas paths inside of it and you're going to have two ports back here on the back of it and you're going to have side measuring tips and also you're going to have a hole straight into the end of that tip that measures your velocity pressure so this is a static tip now here's the way i use that ball inflator needle this is the fitting that's in my manometer kit it's the eighth inch pipe thread that goes into gas valves so that i when i screw that into a gas valve and then i found some silicon tubing that goes between the threaded portion of that ball inflator needle and the threaded portion on the the eighth inch pipe thread fitting and just slides over there real nice i found that actually at a hardware store and i was like oh hey this is perfect i can just pop it on here pop it off when i need to again really handy little tip for measuring so again static tip orientation this needs to be pointed with the airflow you can either point it in into that airflow or you can actually point it 90 degrees away from the airflow i prefer in if i can get it that's the prescribed method but you can point it away if you have to you just don't want it sideways in there right where that error is is pushing into the side of those holes because if you do that then you start reading velocity pressure and i'll show you a little bit about that in a little bit now say you want to try out an alternate tip okay so when i first decided i was going to try this ball inflator needle because i needed something that i could go through the screw holes and a cabinet on so i didn't have to drill holes in a cabinet so i grabbed this ball inflator needle and i'm like how am i going to prove this right well it's pretty simple you use the differential pressure on your manometer so you can prove out any tip that you want to try for static by connecting it to a known tip which is your static tip hook the other side of your manometer up to your proposed tip that you want to use and you should see zero differential pressure between those two if you start seeing differential pressure one of the tips is not reading right it's going to be your alternate tip because that static tip should be reading correctly provided you have it inserted correctly all right so that's an easy way i've seen people use copper tubing um some people like to use a little cap tubing capillary tubing from refrigeration systems because it's long and you can form it and get it around corners and things like that to take measurements and stuff in so just prove it out like this make sure that it's going to give you an accurate reading if you use an alternative tip style okay now let's look at test locations okay so test locations is where in the duct we want to test and one of the things we have to look out for is air turbulence in the duct because if we get air turbulence happening inside that duct then it will come in and it will it will falsely affect our reading and it will be pushing in on the side of that so if you have a sharp corner like this this is kind of how air looks when it tries to turn this sharp corner think about driving down the street in a car and you come to a sharp corner in the road you can't make that you can't come down here with any speed and make that turn and just head the other direction you're going to take that corner wide you're going to swing way wide well air does the same thing because once it's going this way it doesn't want to change and go this way unless it has to well this wall kind of forces it so if we put a static tip in here right we're going to get a bad measurement same thing if we put a static tip in here even though this might be going fairly straight we're still going to get a bad measurement because this right here is effectively effectively shrinking this size of this duct right so i'm using about maybe two-thirds of that duct and i've got a third of it sucked up in turbulence so i'm actually going to get a high static pressure reading if i insert my tip too close to this corner versus if i put it in up here now things are straightened out and i can get a real static pressure reading that kind of makes sense all right so be cognizant of where you're putting your tips in and taking these readings now it kind of depends on what you're doing with the reading as to how accurate you really have to get if you're looking for a year-over-year comparison reading okay maybe you can put it in right here because if something changes you're going to see a shift the absolute doesn't matter the absolute reading does matter when you start trying to use blower tables and things like that which is what we're going to talk about later on all right now so and this was another note i forgot about try to take your readings two to three duck diameters downstream of that fitting okay because that generally gets you out of that really turbulent area if you have turning veins in there right those turning veins air comes in and they redirect that air so it stays a lot straighter still about one to one and a half duck diameters downstream is where you want to take that sample at just to get away from any potential turbulence that happens in here now back up one slide this is the second most efficient fitting at turning air and making it go in the corner the reason this is used a lot is for space because we don't often have the space to make these nice wide sweeping turns right we don't build buildings a lot of times or houses with room to put in these giant sweeping elbows with a giant sweeping elbow things turn nicely in there just like they do on a long sweeping curve on an interstate when you're going really fast you can go around that curve real nice and easy you don't have sharp corners at high speeds on interstates or if you do people tend to run off and end up in ditches or walls or whatever and it looks like a you know a sunday afternoon in a nascar race somewhere with a whole lot of cars in a wall okay so again about one to one and a half duck diameters downstream of that elbow get you a good sample all right now let's get into near equipment measurements and and this is something or near fitting measurements this is actually something that i encountered so this setup right here uh we had a return drop coming down gas furnace evaporator coil plenum and then we had this weird funky duct up here that it was elbow elbow and then duct because there physically wasn't space to take the plenum up high enough to make meet up with that duct so the installer said well guess what i can put these nice elbows in here and that'll make the air turn well not really because in order to make an elbow work in a duct you have to have the air going straight into the elbow and a hard radius inside doesn't work well it you it works like that square corner we saw in the very square elbow works the same way so we've got air coming up here trying to make this corner before it can get straightened out it gets slammed up in here and then gets slammed again to try to go down this duck now this system always had issues i didn't install it the the company that was installed it was long gone the company i worked for was maintaining it and they asked me one day they said what can we do about this and i started doing some testing and basically if they wanted to fix it they opted not to it was going to require some major duct renovations here's what we found so you can see these two elbows here right this is the plenum over here all right so i'm measuring in this case right here i'm measuring with that manometer i got a .12 static pressure on that top hole now you'll see i've got a second hole drilled down here and if you look in this picture you see that i've got two holes drilled in there and my probes are inserted but the thing is look at my differential pressure between those two probes this bottom one down here is in a lot of turbulence because that air can't come up and make this turn fast enough so even halfway up that duct where that probe was i had a ton of turbulence back here and the airflow in this duct was terrible this was a very clear instance of seeing being able to see that turbulence with a static pressure test because in essence this duct was not the same dimensional size if you actually drew a line from this corner somewhere up to here and from the bottom corner straight up through this corner you know now you've got just this much duct it was a lot smaller because the fittings were too close to each other to make a nice smooth transition for the air okay so test locations near equipment so this is going to be like an upflow gas furnace with a filter off the side of it down here with a return drop very common in my part of the country some parts of the country not so common i know various places have different things you know if you guys are all from florida um you're probably you know looking a lot of garage systems things like that but air comes down here makes that corner when you get close to this filter below the top of that filter the air is going to start kind of trying to turn and go into that so it's going to get real turbulent down here you want to take that pressure right up above the filter in here in the blower compartment you kind of want to be in the bottom the middle of that filter you don't want to get over here on this side because you start getting a lot of turbulence happening in that blower compartment you want to be as close into the face of that filter where it's coming in as possible then of course we need to measure at the top now between these two points right the top of your furnace and the filter here those two are your external static pressure right this is duct only pressure this is duct plus filter this is coil plus duct and this is duct only pressure right so that's about the four places you take pressure tests when you're talking about static pressure on this type of a system now let's look at a different system okay here's an air handler or a fan coil unit this one happens to be setting on a base and we've got an external filter rack over here we've got duct obviously we need to take up here okay this is going to get us our duct pressure here as well coming immediately out of the filter you want to use these two measurements for your filter pressure so if you need a filter pressure drop those two measurements right there now challenging thing is measuring this box over here because this box is also going to have static resistance because there's no turning veins or anything in here to help turn that corner taking measurement in here is really challenging because it's going to be very turbulent in this box since there's nothing in here to tell it where and how to turn all right we also probably need to take a measurement when we're doing external static pressure we need to take our measurement right here because we don't want to use this measurement because there's extra static in that box so for external static we really need to measure over here and then of course external static on an air handler you don't want to measure external static immediately at the top of the air handler you need to get where the especially if there's a heater kit in there inside that air handler it can be very very turbulent all right so we need to get up typically i like 18 to 24 12 inches is kind of my minimum but 18 to 24 inches typically above that if possible i understand physically it doesn't work all the time now this is another configuration that i've seen with an air handler and a box on the bottom of it so again to get that duct pressure we really kind of need to test over here before we hit this elbow because once we get into that elbow we're going to start seeing a ton of turbulence down here unless somebody put turning veins in this which is pretty rare if we need external static pressure we've got a test between that filter and the bottom of the coil again this is where that ball needle comes in really handy for this because there there's not a lot of space in there typically and it is it can be really hard to get the um a hole drilled in there safely because you don't want to hit the drain pan and you don't want to hit the coil obviously so use that ball needle to go in a screw hole or something like that it's real handy for that and same thing with the supply static up at the top all right it's really hard on this one to get a perfect filter static because if you measure right here that air is is not turning real well and it's not going to be real straight so you would really have to play with it to figure out where the sweet spot is on the airflow and it because of the turbulence you may not ever get a good solid reading in there okay filter grill test location so if we need to test the pressure drop on that filter with a filter grill you need to insert a probe through the filter make a real small hole in that filter somewhere just a little slit with a knife or something and put that probe in there to make a measurement right or if you can get to the duct right behind the filter you know if you're if you're within a couple feet of this fine take a measurement unless it necks down in size if once it next down in size you don't want to do that but a lot of times we can't get to this duct real easily and we just need to come in from the front side of the filter grill okay let's take a little bit more look at static in the duct system this is what i like to call the static seesaw effect so because higher resistance affects airflow if your blower motor and it depends on what type of blower motor you have as to how this works so if you have a piece psc or an ecm constant torque blower motor right constant torque which is your x13 style with the voltage taps on it so that you're moving the wires around to select the motor speed then we get a static seesaw if something happens where the return static goes up our supply static is going to go down slightly the reason is because if the return static goes up and affects the airflow the airflow amount on the supply side goes down which means we get that static effect what this means is if you fix a problem you find a problem say you find you have a return problem okay and you fix it and you lower the static on the return now you increase the airflow or the decrease the resistance so you increase the potential airflow now your static can swing the other way and it may be high on the supply now it's the total of those two is the external is what we're worried about so make sure that once you fix a problem re-measure it and make sure there's not any other problems identify the problem fix it re-test to make sure there's nothing else okay but this is how you're going to see static work again psc and ecm constant torque now on ecm constant volume motors it's different works a little bit differently the reason is because that constant volume motor will change rpm to try to maintain a constant volume so if something changes on one side like your return static goes up as long as it doesn't go up enough to limit the air flow volume the supply side is going to stay the same because our air flow volume did not change our airflow volume through the whole system didn't change even though this static went up because the blower corrected somewhat and the blower then draws higher amperage to be able to do more work which we'll talk about a little later all right same thing all right if the supply goes up the return static is going to stay about the same unless the supply goes up enough that it limits the air flow on the return side so you would have to have somebody really closing registers or a fire damper go closed or something like that you're gonna have a major event with a constant volume motor so know what kind of motor you're testing static on if you're using if you're doing troubleshooting with that motor all right now if the blower bearing unit is internally dirty say you have a fan coil unit and the coil or the blower wheel gets dirty in there or you have a gas furnace a condensing gas furnace and your secondary heat exchanger gets dirty what's going to happen then well we're not going to be able to move as much air through the system because those components are dirty so when that happens the seesaw breaks and both sides get low because there's not enough air volume going through that makes sense to everybody okay all right okay so this is kind of my troubleshooting um flow if you will for for static pressure so if i see high external static pressure i'm going to determine whether it's in the supply or the return i'm going to take separate measurements i started the equipment i'm going to test each component down the line until i find something that's got a higher drop than what i look for higher than what i'm expecting i have to know what the drop is on stuff what's it supposed to be on certain components like filters filters are a big thing and near equipment ducting especially on the return side is a lot of external static pressure look for that high differential pressure across those components take your reading start maybe leave one probe at the furnace or at the air moving device and work your way down the duct with different holes and a second probe so you can always have a comparison right then correct the issue if the owner or the the money person wants to pay to have it corrected that's always up to them retest the static pressure and repeat the process if necessary that's my troubleshooting flow chart to work with static pressure now this is another big troubleshooting tool that i used in the field so anywhere i would take a static pressure measurement i always use the same probe type there and you can note it next to it if you want to but i carry a sharpie around in my pocket most of us do right it's right there right there in the pocket you grab a sharpie out my wife hates it because i chew on the lids you know i put them in my mouth and i walk around carrying a sharpie and she's like why are there teeth marks on this well because that's the way i do it i write down the heating and the cooling static pressure next to that test port this is especially good on maintenance customers because anytime i go back to that customer i take that static pressure it's similar to taking blood pressure in a human if i take that static pressure and i know i'm in heating mode fan speed or cooling mode fan speed whatever it is and it's different than what i wrote down there when i either when i started working on the system or commissioned the system originally i can go back and i can say okay now i've got a problem something changed ductwork got smashed maybe the um you know vents closed somebody set a couch on top of a register who knows somebody closed off half the house because we're not using that half the house we don't need to put air over there well right we know how that works out so again this is a really valuable troubleshooting tool and it's just a quick check once you get that set up and get those notes written in there boom boom boom you're done i can take four static pressures in under two minutes right and i've got a good idea of how the the air flow is performing in that system i don't have to take complicated measurements except maybe when i'm setting it up that depends on the system all right now think outside the duct external static pressure can sometimes be increased by duct components that are not directly attached to the main duct system right i just read that verbatim for a reason think about transfer grills door undercuts louvered doors etc you've got to look at that whole house as part of the duct system especially on houses that don't have returns in every room or every space because they're relying on these other pieces of the house to move that air and technically those are really part of the duct system even though they're not necessarily physically connected to the ductwork that we install right i want to say thank you to jenny garcia i don't i doubt he's sitting in here but um i want to say thank you to him for sharing these photos with me because this is what um happens with a um uh louvered door so that louvered door right there is almost .18 static pressure inches of water column across the louvered door this is really common down in florida where you have central um returns in a house he's down in south florida right on this one he's actually he's got a dual port or actually a four port manometer it's dual channel two port manometer from the energy conservatory i think steve rogers is down there somewhere and i imagine you could see one of these in person if you haven't already so his total external static is 0.844 just this louvered door is almost .19 now a lot of times if we're in there doing a maintenance or we're checking out a problem for somebody we're probably going to have this door open right we walk into the mechanical room we leave the door open so we can walk in and out it's one other thing make sure that we're checking this under normal operating conditions don't change something to the airflow when you're accessing that room or something like that because that is is going to change the reading for your system because if he had that door open he wouldn't have nearly this number for external static pressure right so keep that in mind when you're doing your checks now questions about static pressure can you put the um the pressure tips you're talking about like the just the static pressure tips yes you can put them in flex duct um the challenge is anytime you put a hole in something like a piece of duct you need to seal it up afterwards so how would you seal that up because in order to go into flex duct you're going to have to pierce the outer skin through the insulation and then through the inner liner and there's not going to be a good way to um seal that up so can you yes should you that's really going to be up to you because you know especially where you're talking if if that flex duct is in an unconditioned space where it gets hot or cold you may ultimately end up with condensation issues inside that flex duct because of that hole in there that makes sense yeah okay anybody else right now all right you guys doing all right you're not bored on me okay all right let's get into blower settings blower speeds why do we set them all right the factory doesn't know what components we are going to be connecting outside of that blower bearing unit they have no idea all they do is they set the blowers up to make a quick test at the factory to make sure that they run they're going to do a a quick on off test they might run it you know of a gas furnace or something like that they may do a quick run fire on it but they're they're not even going to get a temperature rise really on that thing they're just it's running it's on down the line so it's up to us in the field to set up lower speeds appropriately for our situation whatever it's installed in right so we set them up to match the installed components outside that blower bearing unit first thing you really need to know what type of motor do we have ecm constant volume in today's world we're pretty much going to see ecm constant torque psc is pretty much gone now these two set up the same though so your setup if you were doing it on psc should not change going to ecm constant torque the setup steps are the same thing we're still going to use a static pressure and a blower chart now know your equipment type what type of airflow are you going to set up if you got gas or oil heat you need to get it running with whatever factory blower speed it was get your combustion set up right and then you need to go set that blower speed now you might want to check your combustion when you're done especially if you're using an analyzer depending on what method you're using but get the combustion or the gas pressure at least set then set your blower speed to the middle of that temperature rise range that gives you a good temperature rise coming in keeps you away from condensing in the heat exchanger and it allows you a little bit of space for your filter to get dirty and lower the airflow a little bit okay now when you're in an air conditioner or a heat pump because we're dealing with the refrigerant cycle you need to set the air flow first and then set your refrigerant charge to the airflow unless you're just charging by weight all right but if you have to set the air flow up air flow first then refrigerant charge so ecm constant volume this is what we know as variable speed okay um design equipment airflow you need to know what that design equipment air flow is and we'll talk about that in a little bit no rules of thumb here okay no thumbs no no no thumbs you're going to have to have the install manual it sets up by dip switches or at the uterus user interface through the the thermostat or the wall control that's where you do the setup for the airflow on this when you get this set up optimally it should be at less than 70 percent of your max external static pressure rating can it push up to 100 percent yes can it push over 100 percent some motors will depends on how they're programmed is it good for the motor no it shortens the motor life all right just because we can doesn't mean we should it shortens the motor life and it increases the energy use so if you sell that as a long life piece of equipment and you sell that as a an energy saving motor and you're running more than that 70 percent of max static your customers not going to get what you sold them all right so if you've got a uh say a unit that's rated it at an inch of external static like some of the units are today you don't want to run that over a 0.7 external static that's easy math right you get down into some of the other some of them are rated at 0.7 0.8 again that 70 percent number is kind of the sweet spot um on that motor where it gets into lower energy ranges still keeps the airflow moving gives you a little room for your filter to load up things like that the the real the biggest enemy of these constant volume motors is high static pressure because high static pressure means they have to work harder which means they build up heat because they are an air over motor they're an air cooled motor so if they start building up too much heat in them and they can't get the they don't have enough air flow for cooling so the higher the static the more heat they build up now constant torque or psc constant torque is also known as your x13 motors all right again we need to know what the design equipment air flow is especially for uh i think for air conditioning okay no rules of thumb on this the the 400 cfm per ton does not always apply that's a that's a very nominal airflow the simplest way to do this is with external static pressure it gets you really really close it's the easy way to do it if you need to dial it in more select another measurement like a a true flow grid or a duct traverse or something like that okay this isn't the easiest simplest way to do it external static pressure and get the blower chart out of the installation manual now this is kind of what a blower chart looks like you got to where your return air connection is on this manufacturer shows your wire lead color codes so these are different sizes of units as you can see and they give you an approximate cooling tons like where you should start at and if you look over here that kind of correlates to your 0.5 external static pressure but if you're not running right at five then you gotta make some adjustments and don't go by this right this is a starting point so if you've got a two and a half ton set it on black to start with then start measuring and making sure you've got enough air flow okay now the other half of that is that we've got our whoops let me back up one more here okay so the way to use this i missed one static pressure up here on the top okay and you can interpret interpolate between these two columns this is your external static pressure this is your motor speed over here so whatever wire color or selection now if it's a like the some of the constant torque motors are just going to tell you the number of that speed tap on the side of the motor because they only may only run two wires over the motor one for heating one for cooling and you have to select which tap to plug into on that motor depends on the manufacturer okay now we need to know what the design equipment airflow is and this you have to get into the equipment performance data this is part of manual s and should be done in conjunction with manual j so this is a i believe a three and a half ton unit all right so yeah three and a half ton unit which we're going to zoom in here okay we're going to pick this part over here all right which is our evaporator air and we're going to go over here and look at our outdoor conditions so we're going to zoom in a little bit so evaporator air this is our approximate air flow going across the evaporator coil entering air wet bulb this is very important that we get wet bulb temperature so we need some type of a hygrometer to do that okay some type of a a probe that can measure your wet bulb and dry bulb so a psychometric probe okay over here we have our outdoor dry bulb temperature okay total and sensible capacity and of course this is our our total kilowatts out of that system which we we're not going to worry too much about the total system kilowatts of power usage over there now first thing we need to know on this chart i picked the 95 a because it's a pretty common design temperature range somewhere around 95 and b because this is actually ahri design conditions so this being a two and a half ton unit we've got 41 500 btus right there so that's real close to that 42 000 of a three and a half ton unit 95 67 90 the design temperatures are 95 80 67. so it's 95 outdoor 80 degree dry bulb indoor and 67 degree wet bulb indoor is your design conditions for hri that's where all of your equipment capacity is rated at now it changes from there and how many people run their house at 80 degrees in the summertime i i know of one that used to me but not very often anymore my wife gets grumpy okay so on the chart all right we've got 67 which is in reference to 80 degree dry bulb and this 62 down here which is also reference to 80 degree dry bulb however there's a note a tva rating indoor condition 75 fahren dry bulb 63 wet bulb okay all other indoor temperatures are at 80 entering dry bulb so i'm going to pick and look at my ratings when i'm looking at this at that 63 because that's actually a lot closer to real life indoor conditions and what this is if you put this into a converter over here you can see what i did here is due point so dp is dew point for human comfort ideally we really want to be between 50 to 55 degrees dew point now 75 and 63 is close it's a little high but if i pick this 80 and 62 i'm on the bottom end of that scale and that's freezing it's actually really cold to a human to walk into that to most humans and if you look down here i don't have a lot of latent anymore especially if i get into a 400 cfm if i look at that 62 right here 3882 and 3882 had zero latent removal right there but the reason is because i'm looking at a 50 degree dew point and that coil temperature is running right at about 50 degrees is where our saturation temperature in that coil is so i i can't pull any more latent out everything at that point is going to be sensible which is fine because i really don't want my indoor space going colder than that so we're going to look at this one here and that's kind of going to be our guide we're going to use that 63 degree entering wet bulb column to figure out what we want to do and what we need to do is figure out what our sensible heat ratio is and this number comes from the load calculation a manual j load calculation when you hit that you find out what the sensible heat ratio is and its sensible heat ratio is sensible divided by the total so whatever the sensible number is divide by the total and that gets your sensible heat ratio so you see i've got three different ones 0.73 0.77 and 0.81 depending on what my airflow is so depending on what the load calculation says this is where i decide to set my bloat my indoor air speed at what sensible heat ratio do i need this is your design equipment airflow selection so this really needs to be done before you can set up your blower speed you need to know this information okay because if we go down here we set this for that 0.73 it's not a huge change in btus but you're going to do a lot more latent work down here than you are up here depending on what part of the country you're in if you're in a very dry area heck go up here for this point eight one but in my part of the country and um most places probably east of the mississippi or east of the plains you're going to want to set somewhere between that 400 cfm per tonne or 350. so this is at your 350. right so this is where we we get rid of that rule of thumb now did everybody kind of uh understand that any questions so far okay now setting up with an internal filter how are we doing on time here we're moving right along we might actually get done early you guys aren't asking enough questions so setting up with an uh an air handler a lot of air handlers and i don't think any furnaces anymore come with internal filters there used to be a couple but there's still some air handlers out there they come with a throwaway essentially rock catcher plastic filter in here the thing about that is that most of the time that filter drop is included in the external static pressure rating so if we take that filter out our blower charts are no longer accurate you start having to do some some funny math to try to get that um taken out of the external static pressure right so when we're doing our air flow there's a couple things i like to see on that now if you've got an external filter that you're adding on for better filtration i don't recommend putting anything more than that rock catcher in this filter slot because your static pressure is going to absolutely go through the roof it's going to be crazy on you because this filter slot is not large enough for that it'll only handle a one-inch filter and it doesn't use all of that filter when it's in there because the opening in the drain pan is not large enough and you end up using about maybe two-thirds of the filter and you can see that when you pull the filter out and it's only dirty in the middle of it it's not all the way even to the edges so we put in an outside filter here depending on the blower motor if it's a constant volume right because they modulate to to maintain that air flow through the equipment you can go ahead and remove that filter and seal that filter slot up but if you have to use a blower chart and you're using a constant torque motor you may want to leave that in there because the blower chart is not going to be usable per se when you take that filter out because some of those filters have got you know maybe a 0.05 or a 1.0 static pressure on a 0.10 depending on how much air you're pulling through so you may need to leave that in there now depending on how you have this put in that filter can kind of act as a little bit of an air straightener not not a lot not as good as turning veins because like on this situation one of the problems i've seen is if we have an a shaped coil in here right imagine an a shaped coil in there that airflow comes down in here and comes up and ends up all in this slab over here this slab on this side gets shorted on airflow we don't have laminar or even flow volume between both slabs of that coil because again that air doesn't like to make that sharp turn and go back over into this slab so that filter in there may act a little bit like an air straightener but not a ton not a ton it's still not going to be good as something like turning veins but this is something to keep in mind when you're doing this setup depends on what blower motor you have in here as to what you are going to do with it all right now any questions on that so far uh back to what you were say something there about an external filter um i'm kind of not lost now would that be would that be a double filter so if you're talking about like this system here where like this blue box would represent an external filter right so i would put i would put like a media filter or something like that over here for better filtration because the filter that comes in this slot is not great at filtering it it's not really even enough to keep the equipment clean but the slot is not large enough for me to even put a merv 8 pleated filter in there and have a reasonable static drop across that filter i'm going to have a lot of static pressure drop across that filter which is going to drive my external static up and i really don't know how to measure it well because i would need to measure the original filter and then start adding on the extra drop of that new filter in there does that make sense the problem is that when i go back to use you know like if i go back here to use this blower chart right because i'm gonna i need to measure outside of that filter that's in the the air handler cabinet because that filter is part of the external static pressure rating of that cabinet so once i take that filter out i'm changing the external static pressure rating on that cabinet that makes sense yeah right because i'm i'm removing some of the resistance that's inside the cabinet that's already included in that static pressure rating in the blower capability so as soon as i take that filter out i change the parameters and this chart no longer works okay okay good question good question though thank you so we got a question from the chat window regarding uh this so the answer is it depends on the motor okay so if you're looking at the constant volume ecm then yeah i'm gonna take this filter out if i have another filter in here somewhere if i've got a constant torque it depends on what technique i'm going to use to measure airflow if i'm using that static pressure to set up my airflow i'm going to leave this in here because that's part of the blower chart okay this filter was was part of the engineering in that blower chart so if i take that out it's really going to change the characteristics and i'm i'm not going to know exactly where i'm setting it up quite as well the thing i want to do is i want to make sure that all this duct work from the outlet of this filter to the inlet of that air handler and all this stuff down here on my air or where that filter door is is well sealed so that i don't end up with a bunch of dirt being pulled in from after this filter here all right so nathan i hope that answered your question about uh about this factory filter in here does all this assume a dry coil not loaded with moisture uh that depends on the manufacturer and you need to look at the manufacturer's literature to tell that some of them use a wet coil some of them use a dry coil some of them have a separate charts for both i've seen it both ways so it's really up to the manufacturer on that depending on how they rate it because the challenge i have with a wet coil is how wet is wet right because wet can vary depending on the amount of humidity that we have in the space i really prefer a dry coil because i feel that's more of a constant uh resistance than a wet coil is going to be let's take a look at some air filter sizing so air filter sizing is an easy way to reduce the external static pressure by putting in a properly sized air filter it's also really useful for the higher merv ratings that we're seeing requested a lot right now because of the pandemic everybody's talking about higher merv filters well if we go shoving a higher merv filter into a system that was barely designed for a merv 8 guess what happens to our static pressure it goes right on up and we'll look at some some charts here in a little bit on air filters so for higher merv ratings especially we've got to put in a larger filter we need that bigger filter put in there to really make things work properly otherwise well we're going to start blowing up blower motors or running really low airflow on things which isn't very good okay it's hard to explain to customers sometimes exactly why why we need to upgrade their filter if they want a better filter just running out and throwing in that that 3m filter from the hardware store sometimes isn't the best thing and we we need to talk to because we're the experts now we can't force them to change it but we can explain it to them now i get asked sometimes about velocity on air filters velocity is used for rating purposes so the really the only velocity that we really need to care about is are we lower than the rated velocity of that filter which is typically around 300 feet per minute depending on what test was done but most of the time if we focused on pressure differential which is what the blower cares about right the blower doesn't care about how fast the air is moving through that filter it cares about the pressure differential so if we focus on the pressure differential of filters we're not going to have a problem with filter velocity okay because low pressure differential equals low velocity as well right in the residential light commercial type stuff with your your static pressure under an inch external that 0.1 inch of water column or less is kind of a sweet spot for filters i like even a little bit less than that if i can if i can fit it physically in there but that's my upper end of designing for a filter size when i'm selecting a filter now always remember size for the external static pressure capacity of the blower because if you're getting into things like the the ducted concealed units for um the mini splits and things like that those sometimes have a really low external static pressure you know some of them have an external static pressure of like 0.2 to point three so man you really have to get your filter down there if you're going to connect any ductwork or grills or anything like that to that it becomes really critical to have a well sized filter on there and the better fill the better the filter you put in the cleaner the equipment stays so a tight filter that fits well in its frame it's the door is sealed up well capture the dirt and not allow it through into that piece of equipment so the other things that we look at in that system in addition to the filter are things the other components like the refrigerant coils balancing dampers grilles registers zone dampers duct duct liner um turning veins if we put them in there which actually improve the static of an elbow so doors like we talked about louvered or undercut doors um jumper ducts anything else that impedes that airflow adds static pressure to the blower and the blower is what cares about static pressure because that's that resistance to airflow is what the blower cares about right so let's take a look at some merv 8 filter data here okay so this is kind of how to read a chart so we got i just picked out some 20 by 25 one inch two inch and four inch all right this is your actual size measurement so these are nominal dimensions this gives your capacity in cfm at 300 500 and 625 feet per minute velocity because remember i said these are all measured at velocity so this is your capacity now this is a standard capacity of filter and this gives your pressure drop at 300 500 and 625 feet per minute at this airflow so pressure drop correlates to airflow alright and this is what they call a high capacity filter from this company which the high capacity filter has more pleats in it so with more pleats we have more actual filter surface area so you can see in the media area here this has i believe this is square feet six square feet seven point four square feet over there uh where ten and a half fifteen and a half and nineteen and a half and twenty three point six so there's quite a bit of difference on filter surface area there but then we look at our airflow we're 1050 all the way down okay so this would be good for that two or you know a two and a half ton unit nominal right 300 feet per minute standard capacity i got to go all the way up to that 20 by 25 by 4 before i can get below my 0.1 desired threshold okay now i could go out to that high capacity and pick a two inch but if you start sizing off what uh you see in the books a lot which is 500 feet per minute okay great i can move that 1050 through my 20 by 25 by one but look at what that costs on static pressure i mean if i pick the 500 feet per minute right i'm at 0.51 holy cow that's just flying through there right but i'm at 0.51 static and that's almost my entire static on a lot of units especially if you're talking about a furnace if you're talking about an air handler most of the time that might be over the external static rating just in the filter so this is really low hanging fruit when you start sizing filters appropriately okay now let's take a look at merv 13. so we kind of see the difference here and this they don't have an extended capacity but again i got that same those same three sizes twenty by twenty five one two and four okay we're looking at um a thousand fifty thousand fifty and thirteen hundred on our one inch at three hundred feet per minute okay at five hundred feet per minute there our cfm is a little bit different but look at my drop on that one inch 0.26 0.1 2.11 if i wanted to do that two and a half ton system i'd have to go to a 20 by 25 by four and you know i can i can squeeze that out of a uh um a system at 300 feet per minute you know but that's my my peak right there you know that 0.11 i can get away with that now we got to remember something else though when we're putting these filters in and we're designing the duct around the filters in order to get these designed static pressure numbers the air has to go straight through that filter it's got to go straight into that media so it hits everything if this is too close to a corner or doesn't have something like turning veins or something else coming into it and we only hit we get that air coming in at an angle well that air doesn't turn enough to go up into this side of the pleat and if you've ever pulled one of these filters out that's close to an elbow and you see like half the pleats are clean and half the pleats are dirty that means your air is not using a hundred percent of that filter surface area which means you're probably going to have extra high static across that filter way higher than what was expected the customer is also not able to use their filter or a hundred percent of that filter so you you get a little bit through here but not all of it especially if you got a really sharp turn right this like if you have a return drop coming down right next to this filter and it's trying to make that all that air turn in in an 80 inch or 10 inch wide space out here all right now we kind of blew through everything here today what's that um furnace with one inch filter can i upgrade that and use a four-inch window well you if you can physically fit it in there yes okay um better surface area yeah you're going to have a lot better surface area you're going to have a lot better um filtration more than likely okay um because chances are that one inch filter are you running like a merv 8 or are you running just like a fiberglass filter in it fiberglass the fiberglass filters i kind of refer to as a rock catcher because they don't catch a lot of that real fine dirt i never heard that before you know they catch rocks and golf balls but the really fine dirt and dust that comes through that filter and then gets our blower fans dirty it it gets the motor dirty so the motor doesn't have adequate air flow through it through the the if there's airport you know air ventilation ports on that motor and then it gets our evaporator coil dirty it you know there's an evaporator coil in the system and all that dirt sticks to all that stuff as it goes through so to me really yeah the filter has a benefit of cleaning the air that goes through it so that it puts cleaner air back in the house i want that filter in there to keep that equipment clean right i wouldn't run my car around without a really good air filter in it why am i running around in my house where i breathe the air you know because if you if you run a no air filter on your car you're pretty much going to trash the engine shortly well i tell you what it's a whole lot more expensive to repair me if i get a bunch of dirt and dust in me over the years than it is to repair that engine so why am i not doing a good filtration job for me i know you made a point of i've seen a lot of filters where just in the middle it's dirty and not the entire um entire filter so it's just getting just one part of the filter is dirty i've seen a lot of those so you're not using a hundred percent of that surface area now that can be from a number of things if you're too close to like you've got a return drop here and your filters here right and that air comes down it may not use a hundred percent of that filter surface area um now let me see i've got oops can i go back to that slide um i'm gonna have to back up a bunch to find that if you're looking at say what kind of filters are you seeing this in are they like in a filter grill or are they in a filter rack in like a filter rack so is the duct coming into them square or round um room round okay so maybe that transition so if the dirt pattern is the same size and the same shape as that duct coming in you need to back the transition of that round to square away from that filter to allow the air to expand and access that whole surface area of the filter if you slam that round duct right up against the filter yeah you're only gonna the you're only gonna use that round circle that's slammed right up against the filter you gotta back that round to square transition away and give it a nice smooth transition so the air can get to the full surface area that makes sense yeah that makes sense okay okay what other questions do you guys have since we've got we've got a fair amount of time you guys are going to have some free time this afternoon um if you go back to um um static pressure um how can you determine i think you i think you're probably touching it a little bit early determine whether you static pressure measurement if we have an issue in the supply or the return yeah i guess it depends on if you're measuring static pressure like so this is you know a pretty common furnace setup right where you got a return drop you got a filter over here or you know you might have a round duct coming into this right so if you've got a round duct coming into the side of this filter here you need to back the transition from round to square away from that and give it a you know a good 18 to 24 inches at least to expand that air out and hit the whole surface area of that filter that's the problem some people don't put any transition they just go right in there yep and that's that's what you're going to end up with when you do that but hey that's good for you right because you can tell them that you know what this wasn't done it's working sort of maybe but you have the option to tell them this was not done in the best way possible would you like to fix it no you don't have to tell they don't have to fix it all you have to do is tell them okay it's not done the best way possible would you like it fixed here's the benefits of fixing it right it's going to cost this many dollars if you want to fix it i you know i hate to see that people get ripped off like that what we call ripped off right but really they got what they paid for they got exactly what they paid for maybe they didn't do their due diligence maybe they bought the house like that maybe they trusted a general contractor who hired a really cheap hvac company but regardless they got what they paid for and now they may want something better and if they want something better it's their time to pay for it that's my that's my uh um thought on that subject you know so to me hey if people want to go out there and buy a bunch of junk they can pay me to go back and fix it i'm okay with that because that was their choice to begin with and now they have another choice to make it's not my responsibility to make their choices um when we're talking about static pressure right and and that's some of that so like this is what you're talking about determining whether or not there's a problem yeah so if we look at this right so we've got our 0.49 but i took an individual measurement i took a supply measurement and i got this value and i took a return measurement and i got a 0.18 i ended up with a 0.49 total that's my external static pressure now say this unit's only rated for 0.3 where am i going to look first for a problem with that with those numbers supply yeah because that's the highest of the two and again it kind of depends on that blower motor in there if i've got psc or x13 it's going to act like that that teeter-totter right where it goes up and down so if i lower this static pressure my total air flow in the system will go up which means my return static is also going to go up because now i'm moving more air through the duct system that makes sense yeah it does okay so that's where i go i look for the problem i fix the problem and then i go back and do my tests over again and i figure out if there's another problem did i get it low enough right because if i've got a 0.18 this is probably my filter plus my return duct and my airflow is probably low if my rating on a unit is 0.3 all right so who knows maybe i got a fire damper closed up here or maybe i've got they closed off a bunch of registers in the house or maybe the cable guy was up trumping through the attic and stepped on all the flex ducts you know he decided they made a good seat while he was sitting up there connecting cables it's happened it's happened before right so you know i gotta go find out where this problem is and i start taking it in little slices i start at that i start right here and i start working my way out through the system and the farther out through the system i find where my problem is and when i hit a spot that the pressure you know goes from that really high to it bounces down really low or tests really low i know that between those last two locations i measured i got a problem somewhere maybe insulation came off the inside of the duct who knows there's all kinds of potential issues but that's the way to test for it because you know if we're not testing we're just guessing yeah you know this is something i really want to start doing i work with a small company for many years and we never never did any static pressure oh yes i mean we had we we had um we had a manometer of the air flow uh use the hand you know good old good old handometer up there yep i got airflow can if you catch that air can you can you count how many errors you can catch out of there and you know it's it's what we did for a lot of years i i did some of that when i started out but thankfully i had some good teachers and yeah you know once once we learn then it's like oh wow this to me static pressure is blood pressure you know every time you walk into a doctor's office they take your blood pressure right every time every time we walk into a forced air system we should be taking its blood pressure and just like the doctor's office we've got to keep records and that's where i like that re i like that record written right there on the duck next to the hole of what it should be or what it was when it was set up or when i started measuring it you know if it's hot if i walk in there the first time and i see high static hey i'm going to go tell them but i'm going to write that number next to the whole because that way if something changes i can say okay well you know and what happens if static suddenly goes low well it could be dirty equipment could be something dirty on the other side of the duct system or could be that a duct fell apart somewhere the the lining i mean i had a lady call me one time and she couldn't she couldn't keep her house warm lo and behold i got i got over there and i started looking and i'm like man i your furnace is running great i thought hey what's what is what gives here well we started crawling i started crawling down in the crawl space and i found out that she had a down flow unit pushing air down into the crawl space right into into a metal duct in the crawl space and her um evaporator pan had broken and had been dripping water down in that ductwork and it just completely rusted out the entire plenum down there she was heating the crawl space now i couldn't take static pressure on that because that coil was slammed down sitting on the floor i had to crawl in the crawl space to take static pressure every time and you know on a simple maintenance maybe it didn't get done so but it's one of those things if the static goes really low on one side maybe you've got a hole in the duct somewhere we most of the time think of static pressure going up but going down tells us something as well and having that pressure you know that blood pressure written on that duct every time i walk in there boom boom boom boom four pressures near the equipment or three pressures depending on what type of equipment you have how much external to that equipment you have i can know that my airflow going through that duct is pretty close to what it was designed or what it was originally set up as and i can also know that that duct system is in good shape you know getting back to what you were saying just so much you know people get what they pay for i went to the details and um she's got a cross piece uh he pretty much can walk uh we jumped out of ben a little bit and all our ducks every one of them were just hanging you know they had bet you know they they they they weren't pulled and i thought i say you know what um this entire workpiece um redoing you know take over all these dark and redo it um she before it just to be you know fix the best way it could she didn't want to spend the money to get it down you know done the right way you know so yeah she kind of wanted a band-aid put on it yeah yeah but um i mean you know um i had to go to people's house and when i see stuff say man who did this you know um and i never like to talk bad about uh other technicians you know um at least not in front of the customer you know but uh it was terrible even though even the uh the the unit um gas furnace uh you know um horizontal for this i mean i mean it was it was a bad bad bad install and the dubs were terrible i said man you get you know you get what you pay for yeah that's an idea yep get what you get what you pay for and that's exactly right so i i had a lot of problems personally for a lot of years you know taking it personally charging someone and it took me a while to realize hey you know what it's their choice and they get what they pay for and you know like i think one day a thing was yesterday in the class when um one of the presenters will say you know on your war corridor you know make note of these things so you know um you know because you you you discuss this with the customer and the decline so if it comes back it's on the world corridor hey they declined but you make these recommendations yep so you call you cover your hand yeah yeah i mean that's a valuable tool keeping keeping recommendations on work orders and it's one reason why i really like a lot of the electronic tools that we have today because um it allows me as a technician to go back out to somebody's house and i have an electronic record right in front of me i don't have to call an office and have them pull something out of a file or wait for the customer to look something up in their files or find something boom i got it right in front of me and it it makes things a lot easier especially when good records are kept so um what else you guys what do you have any other uh any other questions got another question back with um fresh static pressure test um tip and i need to make sure i call it right uh the pressure probes or the pressure tips yeah now you said the preferable way is in the air stream but put it in the air stream but even if you turn it the other way it was still um it would still read it would still read uh it doesn't matter where you turn it but it's preferable to put it into your stream give me give me just a second i've got one here in front of me let me grab it out of my bag and i'll show you exactly what i'm talking about okay sorry i had it sitting on the floor here so static pressure tip right you can see that it's got holes in the side of it and you want that air flowing around it like this so you can point it into the air stream or you can turn it 180 and point it like this as long as that air is flowing this direction across it what you don't want is you don't want that air flowing straight in a little confused about that but uh i think uh for the first time i uh i really got it this time okay good oh um how can we um is there any way we can get that presentation in literature form um i do i will have to i haven't released it yet um because this is my own presentation so i run a consulting company where i do i do this training so i really don't release that stuff in in literature form per se um so it does other than the slides you see there's everything's up here in my head so that's contact information if anybody wants to get a hold of me right there that's my email address um you know feel free to email me i will uh i'll give you a hand and help you out if i can if i if i'm able so looks like we got done a little bit early today thanks for watching our video if you enjoyed it and got something out of it if you wouldn't mind hitting the thumbs up button to like the video subscribe to the channel and click the notifications bell to be notified when new videos come out hvac school is far more than a youtube channel you can find out more by going to hvacrschool.com which is our website and hub for all of our content including tech tips videos podcasts and so much more you can also subscribe to the podcast on any podcast app of your choosing you can also join our facebook group if you want to weigh in on the conversation yourself thanks again for watching [Music]

Channel: HVAC School

Views: 108,746

Keywords: hvac, hvac school, static pressure, hvac technician, air flow, static pressure hvac, hvac troubleshooting, hvac installation, air conditioning, static pressure hvac tool, air flow hvac system, measure air flow, how to, hvac training videos, static pressure test, smart probes, air conditioning system, Eric Kaiser, hvac/r symposium, bryan orr, static pressure vs airflow, static pressure explained, static pressure fans vs airflow, static pressure vs dynamic pressure, Airflow

Id: ddhQrxuIbUI

Length: 94min 29sec (5669 seconds)

Published: Sun Mar 28 2021