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He just has his room wallpapered with the announcement article, Brian or alright. Alright, this is the HVAC school podcast, the podcast. It is there to help. You remember some things you might have forgotten along the way as well as help.

You remember some things you forgot to know in the first place, like many of us technicians do we know what we know, but often we don't learn things. We don't know because we're busy doing what we do right, and this is an opportunity for you to think about some things and learn some things. And maybe you don't do a lot of, and today we're talking about something that you probably don't do a lot of, and that is water, air handlers, air handlers that use water as the cooling medium instead of refrigerant and we've got Eric Mele who's. Gon na talk to us all about it, so here we go alright, so we've got the great Eric Mele back the podcast again thanks Eric for coming by second mandatory podcast, the second mandatory paid chalo services podcast today we're talking about chilled water air handlers.

So we've already talked a lot about chilled water in the past and not really that much. But we've talked a little bit about it and we've had Jeff Neyman on the podcast a long time ago. Talking about chillers, you can go back and listen to that. If you want to hear more about that, but this is more on the air handling side, and this is everything from residential commercial.

Everything in between you're gon na see these types of applications and really what we're using is water in your traditionally. We would think of as our evaporator coil, but now it's just a coil, that's just our cold coil! That's running chilled water through right, exactly I've been informed by Brian as well that I only get seven oh by the way on this podcast. That's my limit! So, if I forget anything, that's why it's cuz. I went over my oh by the way limit mm-hmm.

Let's talk first about some of the different configurations that these air handlers can come in. Typically, you're gon na see them in every configuration you're used to seeing air handlers in you can have just regular up flow that look exactly like a residential air handler pretty much pancake units. It's a big commercial units that might be setting on the floor in a mechanical room where they might be rooftop pretty much any configuration you've seen another air handler and although these probably go a little bigger than regular direct expansion, air handlers so as opposed to direct Expansion, where we're using a refriger and we're changing it state in this case we're just flowing water through the evaporator coil. So what are some of the things that you'll notice that might be different on the inside of these things, from what we're used to the first clue is going to be? Both pipes are going to be insulated in the same size, and you might see actuator on the pipe outside the unit for the water flow.

You might also see a four pipe arrangement where that would enable them to run cooling and heating in the building. At the same time, whereas, if you have a two pipe arrangement, you have to switch totally over from cooling to heating the whole building, which is common sense. I mean, obviously, if you've got the cold water supply, cold water return, hot water supply, hot water return right. I mean that's what a four-way valve would be pretty simple, though there'd be two different coils.

It had two separate loops, so you might run into that, but in general, especially where we are, you see more of the two pipe configuration and obviously, if you're just flowing water through the coil and it's all gon na be very low temperature. And then that's what you have to insulate both lines. So, regarding insulation on these pipes, you have to be very very thoroughly insulated or they will just drip a lot. So you really want to make sure you're insulated well and, if possible, with your piping when it connects to the unit, there's not going to be any insulation, but you're gon na have a drain pan.

You want to make sure that your piping to the unit in such a way that, if any moisture were to form inside the insulation, preferably it's going to leak out into the unit into the drain pan and not become a problem. So if you can install your two or three way valve over the unit drain, pan that's ideal, then you don't have to worry about insulating it as much or as good. Some of the units are gon na, come with additional pan that you attach to the primary pan - that's gon na slope into it, and they intend for you to put your valve over that and your piping connections. That way, any water dripping is just going to go into the unit pan and not be a big deal, and so the insulation is generally what 1-inch insulation on these people say you can get away with thinner.

Typically, here in Florida, I like to use one inch wall right. I don't have issues with that Armagh flex. One inch wall works pretty good on smaller piping. I've seen it used on bigger piping, but they also use that closed cell foam insulation.

That comes split. It's usually like white on the outside and they call it fart rock, because when you cut it it smells like a fart. That's what guys! Probably I've never done that Lee. You usually see that on the bigger steel piping and for piping, okay yeah.

I know we're talking about now: yeah yeah, it's almost like fiberglass insulation sort of on the inside of it. No it's like black and it's really hard closed cell phone. It's not flexible at all. If you touch it, it's got no give to it whatsoever.

Okay, I've seen them insulated with fiberglass type insulation, but I don't think it was a good application for it, because that building always had problems with insulation, sweating and I'll had to replace a good bit of insulation. Because of that. So what temperature did? These things usually run. Typically, I see chillers set for 44 degrees supply water temperature, not 45, not 43.

That's typically. What I see I mean it would depend on your application, whether you can get away with higher or lower and the further you get from the chiller. The more it's gon na you're gon na gain a little bit right, most likely depending on your conditions and where the piping is run right. Thermal means.

Let's talk about Inlet valves. What different types of inlet valves do we have so you're gon na have a two way or a three way valve on your water loop. Your two-way valves are going to be on systems that are mainly on variable water flow, where the pump actually has a drive. So that it can change the water flow of the system, so a variable frequency drive yes, okay and a three-way valve is going to be more on a system where the pump runs at a constant volume so that you're diverting the water when you're not using it.

In the coil, so when the system goes off, you're bypassing it basically through that three-way valve exactly and the two main things you'll see with a three-way valve is they're. Either they go on the supply side, it's called diverting when they go on the return side. They're called mixing so you're gon na want to look at the directions that come with yours and see where it has to be placed and make sure you're installing it correctly, because some of them can do both, but some of them are meant to do only diverting And there's probably some that are meant to do only mixing, but usually I see only diverting or mixing and diverting and the ones that I've fused. I can't even envision why it matters in my brain.

I've heard somewhere that mixing is the preferred set up, but that's all I really know about it got it, which is that's on the return side, exactly there's, also different types of valves. You have standard open, closed in the new house to have some proportional valves. You were saying yes, so you'll either have a valve. That's either all the way open or all the way, closed, on/off, basically or you'll have ones that are varying how much they open.

That's, usually on a bigger air handler because they usually run a constant airflow. They always the fans, so they just dial back the water as needed to match the load. We think of variable air volume systems are kind of like that, where we vary the amount of air going through and we maintain a constant temperature and that it changes kind of sets in the temperature a little more stable in a space. In this case, the air is staying, constant and you're varying the amount of water flow through the water coil, it's kind of similar to that, but that would be like variable water flow or something I don't know, there's probably no name for that.

I just made that up. That's probably what it's called also you'll see a lot of commercial applications where they use these with Vav boxes, and it works really well because you don't have to worry about flow. Your water is always being delivered at 44, so you can't possibly freeze up the unit, so you can run whatever fan speed. You want it doesn't matter so that they work really well with Vav s.

I imagine it does still impact latent humidity removal, slightly, though, depending on the amount of air volume changing the amount of air moving through the unit they're changing the amount of air UD humidifying so yeah. I shouldn't have said that, because now that's kind of confusing because you have higher air velocity, which is going to impact your dwell time on the coil. But then, if your dehumidifier more air, then so in a Vav application. You're gon na reference static pressure to control the fan, speed across the coil, so you're gon na have a sensor and the sensor is, you know, try to maintain a fixed static pressure, usually 1.5 in the supply duct the common target, but then at the Vav box Itself at the box side, this is sort of a side note here, but you can have eav systems in which the box is the nono.

What am I talking about? Exactly we're talking about you're gon na have Vav boxes downstream and they're gon na be either opening and closing or modulating, depending on what type you have and they're. They want a constant supply of 55-degree air, let's say at 1.5 static, so they know how much air is going through, so they can work properly. I just got my brain twisted there, but yes, so you could have a water coil, a chilled water, coil Vav system and that's what we're saying yeah, it's really good for that. Obviously it's Vav, that's variable air volume, so you could have a variation in air volume depending on how many Vav boxes you have open or how wide open they are, and obviously that would tend to impact the temperature across that coil.

But if you have a system, that's also ramping capacity in order to maintain the water temperature, then those two gon na match up really nicely yeah. So there might be a slight variation. But again, the goal in all of this is to maintain fixed evaporator temperatures or, in this case water coil temperatures, because then that maintains d, modification and kind of does a pretty consistent job there and we want to maintain fairly fixed targets within our spaces. So if you set it to 75 degrees, you don't want it bouncing up and down in a wide bandwidth, because then that impacts, comfort and impacts a lot of different things.

So you wanted to kind of maintain in that dead Bandhan in this application. It kind of does both pretty well yep, so I want to take this opportunity to talk to you about one of our great sponsors and that is aro. Asus Aero Asus makes indoor air quality products here in America, they source the parts as much as possible to make these indoor air quality products from America, and they do it not only because they're Americans and they're Patriots, but also because they can really control the product. The quality of the product, and that's one of the main things I like about air Oasis, is the products that they make specifically the Nano and the bipolar, 2400 or products that they just last and they just work.

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So one thing that I wanted to mention real quick is: it is tough to get readings and I'll actually talk about that right now, like what kind of readings can you get off of these air handlers, that's the challenging part. A lot of times is because you might not have the access to get the readings you need. It probably comes back to cost and how well you tend to need to insulate the piping but to have test ports now you're compromising your insulation plus. You have to add the test port Plus.

Will anybody ever be able to find it once it's buried in insulation, but there might not be pressure test ports that you might be lucky enough that there are gauges installed on the larger air handlers. There usually are temperature and pressure gauges now, whether you can believe their readings on them is a entirely different thing, but at least you have something to go by, but on the smaller units you'll probably have neither and you'll, probably won't, even have a port to add One if you needed to, and so I was suggesting that you could use something like to test - oh six or five eyes, or the uei hub to some sort of air antal, pea probe that you could use where you could measure the enthalpy split across a coil. Like that and if you knew the air flow, which again that's another difficult thing, knowing the airflow is always a challenge. But if you did, then you could use that to calculate approximately how many BTUs you're removing and you could compare that to specs, which could be useful.

But again it is always sort of challenging to know exactly whether or not it's perfect, but again with a simple system like this there's not as much that you have to check. You've got to make sure your water temperature is within range and have some indication that, obviously you moving the air it should move, so you've got to check blower wheels and all that kind of stuff, like you typically would yeah. So, at the technician level, if you're there and somebody else takes care of the chillers and pumps, they might not give you access to make sure all that stuff's working properly and they also might mislead you about the status of that equipment too. If you're like in a condo building and they're supposed to be delivering a certain amount of chilled water - and maybe one of the chillers is offline, but they don't really want to tell anybody.

You can get calls like that. I've been on a few like that. Worse, like I don't know what you want me to do, because I can't touch the chiller there's. Definitely the separation here and a lot of those types of buildings you'll have it with the water source units as well.

You had mentioned that you sometimes run into line voltage. Controls on these yeah you'll see on I shouldn't just say older ones, but you'll see a lot of line. Voltage, controls, I've, seen 277 line voltage or the stats on the wall were actually two. Seven.

Seven line voltage and sometimes two you'll, have it integrated in the stat for fan. Speed on these because you can run whatever fan speed. You won, it's not gon na really ever potentially freeze the unit, so you might have a thermostat on the wall that has like four fan speeds right on the stat or you might have a separate fan, speed controller or they might have just wired it to the Fan speed, they wanted it to be and left it there on some of the smaller units. What about cuz? You mentioned that you got to be careful with replacing 3-way valves with two-way valves yeah.

You want to make sure that you're putting the right valve in for your application, because if you didn't have a variable water flow ability, you don't want to put a bunch of two-way valves in because now you're gon na start to affect the water flow. As those valves start to shut down and then just as a general rule with working with valves - and we talked about this previously - you got to be really careful whenever you're working with any valves, shutoff valves any type of valves that you're working on you really want To Pete gentle, because, obviously, when you have a system of where it's got pretty significant water flows, you'd break those things. You've got a major major problem on your hands and being prepared for it is very difficult to do. You keep in a few rags in a bucket.

It's not gon na help. If you these crazy water flows, I mean, maybe you have a little tiny leak, but not if you actually break a valve off or something it might be. A good idea whenever you're working on a big water system like this, you definitely want to coordinate with building maintenance, have their phone numbers available in case there's an emergency, and maybe, if you have enough experience, have them show you where the pumps are and the what Makeup water is, and if the worst happened, you have to shut off the pumps on the makeup water, somebody's gon na have to it doesn't matter at that point, you have to shut it down. Water is gon na flow and hopefully you're not on the ground floor and has 17 stories of water above you, but hopefully you never have to be in the situation but always be prepared in case it happens, not just stand there watching it like, oh well, alright.

So, let's talk about, you said some of the coils will have air bleeds on them pretty much most of the ones I've seen are gon na. Have an air bleed somewhere on it? It might be hard to locate it might not, but it'll look like a little threaded fitting welded on there and there might be something you turn with a flathead screwdriver and you can start to bleed the water out after a couple revolutions. You should be either hearing air or water come out. You don't want to back that thing all the way out right, because you might not be able to get it back in if it just shoots out of there and right waters under pressure.

You might have significant water pressure behind that. So me carefully. I don't just go crazy, pulling that thing out and it's just an air bleed. Can you get any information at all from that? You can know that the coil is not air bound and if you have water coming out, you know you have water pressure.

So I really can't tell how much flow you have, and you were mentioning that even on to a valve systems where all the valves are two-way, you still want to have some three-way valves towards the end of the loop yeah, it's nice, if you can have them At the end of each branch, because if you have a building, let's say the piping comes up in the middle of the building and you have the hallways going each end at the far end. It would be a good idea to have a three-way valve just to keep the water mixing good in case a lot of valves start shutting down right. That way, you don't have just stagnant exactly made from that. We don't have huge variances in water temperature.

We covered two-way valves in 3-way valves, but you know we didn't cover those actuators okay, so your actuator is gon na sit on top of the valve and gon na be separate from the valve and they usually thread on, although the bigger ones will have more complicated Attachments to attach to the valve and that's what you're gon na use to control your water flow, so they'll either be on-off. We actually said the valve is going to be the on/off part, but that's not true the actuators. What's going to determine that, so the actuator is gon na determine how much water gets through your valve and whether it can be variable or just offer on that's, basically what you're looking at. If you see two wires go into it only.

You know it's gon na be just spring return, so in pool heating, we do this a lot, they have 3-way valves and pool heating, and it's essentially it turns a gate around the three valves and it only shuts off one of them when you have three ways. So it's either going in a case of a pool heater it's either flowing through the pool heater or it's bypassing around. It is one configuration and there's others as well. I imagine it being something like that yeah and in that case yeah, that's pretty much it, but if you see four wires or more going to it, it's probably a variable valve right.

We write the proportional valves. You were talking about too right. You might have a power open power closed valve too, depending how big it is, but the smaller ones a lot of them are spring returned, does a spring open or spring closed generally. It would depend on where, especially if you get the multiple valve that can be mixing or diverting and how, because they'll have like a a B and an a/b on them, I mean it all depends how you pipe it you'll see piping schematics for what you want To do so, it can depend on how you orient the valve and I'm sure you could probably get actuators that go the way you want them to go.

It's specific to your application, all right anything else we missed here, not that I can think of all right. So there we go, there's our chilled water, air handler basics, thanks Eric no problem thanks for listening to the podcast, thanks for being a part of what we do here. If you haven't joined the Facebook group that I'm gon na say hey, why don't you go? Do that the Facebook group, we have a lot of good conversations over there on Facebook. If you're, not in a Facebook, hey no problem, you can also interact on the YouTube channel, so you go to youtube and then just go to youtube.com forward, slash HVAC our school.

You can find us there that's another way to interact and there's a lot of other ways, so we got an app coming out soon. You can go to the website HVC our school comm. That's one way a lot of different ways, and I want to hear from you I, like you, you're in my business you're in my trade, we need people like you, people who are willing to learn and grow and all that stuff. So thanks for listening all right, one thing that I've been experimenting with is wearing two different deodorants, one under each armpit.

I think it's great. I think it's the way to go, but that's just my two cents. Thanks for listening, we will talk at you next time on the HVAC school podcast. Thanks for listening to the hvac school podcast, you can find more great HVAC our education material and subscribe to our short daily tech tips by going to HVAC our school comm.

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