What i want to talk about today, i want to kind of go off of the regular schedule because we're getting into both a warm and wet season. We had a lot of rains last night. So what comes along with uh, rainy and hot anyone know discomfort discomfort. What else humidity, what else steam? No he's, not wrong, not steam.

He is wrong. He's wrong steam, okay! Oh there, you go yeah hot compressor. That could happen. He saved you there that jacob's got your back man yeah.

So you start to get moisture related issues and some of it's comfort, but some of it is things like sweating, ductwork, sweating, vents, sweating, air handlers, all those sorts of things right. You ever see that ever see mildew growing on a supply plenum anymore. No, never, it doesn't happen anymore. Yes, it does hololura.

I'm glad air conditioning hasn't changed since i've been out of the field for the last 27 years. So i want to talk about why that happens and what to do about it as a service technician, because sometimes we get the mindset like well. What can we do right? So what's the first thing if you come up to a system and we're going to talk about a few different categories, but let's talk about a system with a sweating air handler eye or sweating ductwork. I put those in the same category sweating air, handler sweating ductwork and why are those in the same category different than a sweating vent? Why are those? Why are those two categories different from each other, where events located inside what the conditioned space right so vents are in the space that should have the humidity controlled, so when they're sweating, what do we pay attention to? What's going on inside? The space like is the humidity high in the space, and why would the humidity behind the space right that'd be the first thing you'd think about, but air handlers furnaces, coils, ductwork they're outside of the condition space, so it's kind of a different thing right.

So, if you're, not in the conditioned space, what what is hard to control the conditions around the doctor working around the air handler right so like you're in an attic for example, what do we do to control the conditions in the attic you could you could insulate? In some cases, attic vents right, you could do that, but what's the problem we're trying to solve for here. This is i'm glad you said both of those things, because what's the problem we're trying to solve for when things are sweating, what is the problem humidity? What's another word for that: let's throw out words for it. Dew point: oh this guy's smart britain always has it. You know he's always got it.

There he's a little slow with it, but it when it comes out. It's always cold dewpoint. What else? What are some other words what'd, you say yeah, you did. You said something i saw it.

He said something moisture water, water, vapor. Whatever you want to call it right. You already said humidity, but not by connections. That's a whole different thing.

Hopefully it's not relative humidity. If you know what i'm saying never mind, that was a little west virginia joke there, hey if you're in any of these groups. You know that joke comes up all the time anyway. What we're trying to control for is moisture.

That's what we're trying to control for, but what do we do when we do things like insulation or venting? What are we controlling for? Do insulation and venting help with moisture? No, what do they help with heat temperature? We can do things, for example, that drop the temperature of an attic. Does that decrease the amount of moisture in the attic the amount of water suspended in the air? Well, here's the trick is that it actually can. If we get to dew point and then it starts to sweat, we're actually reducing the moisture in the air right, we're getting to 100 relative humidity and now that water's starting to come out of the air and end up on your ductwork right. So we're doing a really good job dehumidifying the attic when all of our ducts are sweating right.

That's i mean think about it that way. So what do we do in order to dehumidify the air inside the house? What do we do? What's the magic? This isn't! A trick question boys, it's all right, i'm slowing down, run it over a cold coil right and what what is the temperature point that the coil's at that makes it start to build up, moisture and condensation on it? What's that called britain dew point there we go. It's called dew point right so that coil is below dew point. So when the air runs over the coil that air gets to what percentage relative humidity 100, the point at which air hits 100 relative, humidity, i.e, saturated, i.e, dew point it starts to give up its moisture to the coil right makes sense.

So if i take a cold glass - and i set it in this room - and it begins to sweat where's - that water coming from there around - it's not sweating from the inside out of the glass right, it's condensating on the outside of the cup. And why? Because that cup is below dew point, which means that the air that comes into contact with the with that cup gets to 100 relative humidity and gives up its moisture to that cup. So that cup is dehumidifying the room not much, but that moisture that shows up on the outside of the glass is pulling moisture out of the air and onto the glass. Does that make sense it's doing the exact same thing is why your evaporative coil drains water out the building, it's hitting dew point, and so, when we have ducts that are sweating in an attic or an air handler, that's sweating in a garage.

What is it doing? Well, the air handler is dehumidifying, the garage and the ducts are dehumidifying the attic because they're hitting dewpoint changing the temperature of the garage. So let's say we drop the temperature customer says my air handler sweating. I think i should insulate my garage to help with my air handler sweating. What do we say to that? What we say is that's fine whatever you know why? Because we don't want to argue with the guy he's an old guy he's an engineer.

He lives in the villages. We don't want to get in a fight with him. So we say it's fine, but it's a terrible idea. Why? What are we doing to the temperature of the air and the space we're lowering it? What is that going to do to the surface temperature of the air handler? Is that going to make it go up? When we make the space cooler it's going to go down too right? We drop the temperature in the garage.

We dropped the temperature of the air handler surface. So what did we just? Do we made it dehumidify, the garage even better, which means that it's going to sweat more, do you know what we could do in order to keep it from sweating? Let's come up with some really creative ideas. How you could keep an error handler for sweating if cost was no object? What could you do? Okay, that's one possible solution, but a mini split also cools the space. So maybe, but maybe not some mini splits might not.

Actually solve the problem, many splits actually aren't great at dehumidifying and we'll we can talk about that later. But the easiest way to keep an air handler from condensating is to take a space heater point it at the air handler and let it run 24 hours a day. What does that do in order to keep what does that do to keep the air handler from sweating? It heats the surface of the air handler up, which does what keeps it from hitting dew point right same thing with the glass. If i take the glass it's sweating, i point a space heater at it.

Is it going to keep sweating? No, this will stop sweating. Why? Because i'm heating up the surface of the glass make sense. What do you do if you're trying to get if you're, trying to get moisture off the outside of your windows on your glass and your car? So we're not talking about you know, of course you do the wipers, but the outside just keeps condensating. What do you do you put heat on it from the inside right? What does that do heats up? The outside of the glass keeps it from condensating when you go to a customer's house, and it's got a whole bunch of moisture on the outside of the windows.

When does that happen in the villages, for example, when you see a bunch of moisture on the outside of the glass, the outside of the vinyl happens when they're keeping it cold inside right, the colder it is inside in the summer, the more likely there's going to Be moisture on all the glass, so what do you do to get the glass from building out moisture? Don't keep it so cold or get better glass? So that way the outside is at a warmer temperature compared to the inside. Does that make sense? Everybody followed me? So far, so let's talk about some real prescriptions here. So if you've got ductwork, that's sweating, we say: well, we should put a radiant barrier in right. Have you ever seen? You know, you know what everybody know.

What a radiant barrier is that foil on the deck of the you ever been in an attic with a radiant barrier on a hot summer day. Does it feel nicer up? There sure does feels way. Worse, bert. Just just hang with me here.

Okay, all right! I know you're not the star and it's hard for you right now, but if you can just hang with me for a second, it feels great. It feels more comfortable because the temperature's lower but dropping the temperature did that do anything to reduce the amount of moisture in the attic. Yes yeah, because it lowered the dew point. Well right i mean because everything starts sweating, and so then that causes the letter to be less moisture in the attic right.

But what did you do well by making the attic cooler? What did you do to the surface temperature of all your ducks? Did you make them hotter or cooler you made them colder, so did you make them more or less likely to sweat? You made them more likely to sweat what happens if you take an attic that isn't very well ventilated and you add a bunch of ventilation to it. You put an attic fan on it. You put a bunch of vents like that. That's going to solve the problem.

What does that do the temperature of the attic lowers it? What does that do to the amount of water? That's moving through the attic per hour? Is there more or less water moving through the attic there's more because? Well, it doesn't matter if there's more air moving through the attic there's more water moving through the attic stands. The reason right, if you take an attic and you seal it completely the amount of water, that's in that attic is static based on the amount of air. That's in the attic right! So if you dehumidify that air in the attic, eventually it's going to get below dew point and now it's going to not sweat anymore. But if you keep moving new air through the attic cooler attic, more air moving through ducks are going to sweat more so the worst sweating addicts that you will find and if you start to think back and if you start to look forward as you go in Attics the word ducks sweat.

The most are going to be well-ventilated addicts with radiant barrier because you're giving it a lot of moisture and it's nice and cool is your mind, blown right now, bert, oh my gosh, my poor brains. So what do you do in order to keep an adduction sweating in an attic? Well, you so much of my life has been wasted. You seal the attic and you dehumidify the attic, so you seal the attic you put a dehumidifier up there yeah you can spray! It from it, but you wouldn't have to see here's the trick. Spray foaming spray foam is what what is it? Actually, it's an insulation right.

So what does that do to the temperature of the attic makes it cooler which? What does what to the surface temperature of the ducts makes them cooler right? So insulation and radiant barriers are good for power bills. If you want to drop power bills, you add insulation, you add radiant barriers, you add ventilation, you do all those sorts of things that helps with power bills. Does it help with moisture? No, it does not help with moisture what helps with moisture getting the moisture out of the air right or containing the air so that you're not giving it more air heating things up can also decrease condensation. Now, heating things up is kind of a trick right because that's usually not it's not usually easy to do, but if you have an attic where the ducks are all sweating and it's got radiant barrier, you know what the cheapest way to make the duck stop.

Sweating is rip out the radiant barrier and the client's going to say well, but i just paid for all that and isn't that going to increase my power bills. The answer is yes, it is going to increase your power bills and, yes, you did just pay for all that and now that's wasted, but will it stop your ducks from sweating yeah? Probably because that's probably when they started sweating, how about customer puts a new roof on and now they ventilated it really good in its new cool roof technology where they? Maybe it's got the you know: new cool roof shingles or it's got the it's got the radiant barrier right on the roof, underside of the roof decking or whatever, and now all of a sudden their ducts are sweating. Well, the funny thing is we happen to put a new ac system in, at the same time, because they're making lots of investments in their house right so who's to blame. Well, they blame us because it's our ducks that are sweating.

Now we didn't change the ducks. Probably right, so what is it? Well, it's this new fancy equipment. That's doing it right! What do you think changes the surface temperature ducts more, the inside temperature of the air in the ducts or the temperature of the air around the ducts? What changes the surface temperature of the duct more the air around the ducts, and what do we do when we've got ducks that are sweating? We keep trying to mess with the temperature of the air inside the ducks, because that's the only thing we can do. We go.

We make a setting well we're going to increase airflow on this unit. That's going to help. I mean especially on youtube people catch on to this, i'm stealing, almost all of this from rick sims presentation, condexation that he did here two years ago, which you all have available to you. It's like a two-hour presentation on the hvac youtube channel, but it goes through like the actual temperature differences, and what it comes down to is is that if you go from the coldest to the warmest air that we're ever going to see inside of a duct, it's Like a 2 degree swing on the surface temperature, like you're, not going it's not going to make a big difference, we put r8 ducts versus r6, you might get half a degree, it's not significant.

What is significant, increasing or decreasing the attic temperature increasing or decreasing the radiant gains of the attic? What's what's the message here, the message is: is that for houses that have moisture problems, making them colder anywhere without dehumidifying better makes the problem worse. So we go into a customer's house, we sell them a brand spanking new infiniti, 15 000 stage brand new super dehumidifying unit right. We put it in what does the customer start doing to their set point when they just got this brand new high efficiency system? And now they can really do what they can lower that temperature, because when tyler or drawny go out, what do they tell the customer we're going to make this place so cold? You can hang meeting it. We just talked about this in a class the other day right, you're going to make this place so cold.

You can hang meat in there. No, you do not want to hang meat inside your house. That is a terrible idea. It's unhealthy! It's not fda rated! For that do not hang meat inside your house now.

The point is, is that the customer thinks, because they got a brand new unit and it saves money on power bills that they can set the temperature lower. And what does that? Do it takes everything and makes it colder, which makes everything more likely to condensate, including the walls, the ducts, the air handler? Everything is more likely to condensate whenever a customer talks about or or has dropped, the temperature of something drop. The temperature of the garage drop the temperature of the closet that the air handler's in drop, the temperature of the attic. The next question we need to ask is well: did we dehumidify that, and if the answer is no, we it's either going to sweat or it's going to be more likely to sweat than it was before.

So what do we do? Well, we get better about communicating the necessity of sealing and dehumidification. That's the answer to these problems: sealing and dehumidification. If we go to a customer's house today and they've got sweating ductwork one of the very first things we should do in that case, customers got sweating. Ductwork we go there today.

What's one of the first things we should do in that case, based on what i'm talking about right now, we should look at the conditions in the attic right. What what's going on in this attic? Is it? Oh, did they add a radiant barrier? Okay, does that mean that they have to tear out their radiant barrier? No, it doesn't mean they have to, but it does mean that the other options are going to be expensive. Are we afraid of giving customers expensive options? Should that be something we're afraid of absolutely not do we care if they take the expensive options or not not really it'd be nice if they did, but we don't really care. Why do we offer people expensive options that actually will solve their problems? This isn't a trick question, because our job is to offer them solutions to their problems.

It's not our job to decide on their budget for them. So what will solve every? Essentially every duct sweating problem that exists in our market seal, the attic and dehumidifier. Now, how can you seal the attic you can foam it or you can seal it by any other means you want. You could take and put peel and stick on the undersides of the soffits and seal peel and stick on the uh or some sort of like duck mask or something like that on the vents and leave the insulation on the roof deck and then dehumidify the attic.

Oh, what's that gon na do, though, what's the result going to be because you need to communicate this too? If you do it that way, what's going to happen, they're going to have a hotter addict, which is going to mean higher power bills right because now you're putting a dehumidifier you're paying money for that you got a hotter addict you're going to pay money for that Higher power bills is that good? Well, some customers don't care some customers, that's not a big deal, but to some customers that would be a big deal so for them. What's the next option foam the entire deck right? Do you have to pull out the ceiling insulation when you foam the deck? No, you don't need to why. Why would you need to we? We are used to doing that. It's clean, so it's a nice thing to do because you got all this dirty insulation, especially in an older house whatever.

So it's a great option, but do you have to no? You don't have to what's the point. The point is to get the attic sealed and get the moisture out of the attic. That's how we solve moisture problems, seal things pull moisture out. So let's talk again about inside the space, our vents that are sweating.

Have you ever gone into a restaurant and noticed sweating, vents or noticed rusting, vents or leaked? You know, they've got the stains around so what's unique about restaurants. That makes them more likely to have that problem. Anybody know. Oh there's one.

That's one good reason condition space. What's that like at like five guys, it's in the condition, space, they're ducks well being in the conditioned space and uninsulated can result in in dripping, but it's loss of control of moisture in the condition space. That's why and why do restaurants lose control, what's happening to the doors, all the time open and close, open and close open and close right, the more the doors are open, the more likely you're going to lose control of moisture inside the space. What else do they have? They have kitchen hoods right, they have kitchen hoods and old school kitchens didn't have any necessity to replace that air that they're venting out with conditioned air coming back in and not just conditioned the air doesn't just need to be cooled.

What needs to happen to the air needs to be dehumidified, it needs to be dehumidified really well, because, what's the thing with outdoor air in florida in the summer, what does it have a lot of in? It has a lot of moisture. It's got a lot of water in it right. So what do they do to try to solve the problem? Oh man, it feels really muggy in here it's uncomfortable. What do they do to try to compensate for the mugginess? They drop the temperature right, so you've got a perfect storm.

A lot of moisture load coming from the outside doors, opening a lot of moisture load coming from the inside kitchens and kitchen hoods low set point. So it's cold all three of those make for a perfect storm for vents to sweat. So what do they do to solve the problem? Well, you know that's where you have vestibules, so you have two sets of doors. That's a lot! That's one of the big reasons.

Why you got that, so it isolates the two spaces, so we open these doors, close open these doors. It reduces the amount use air curtains. Things like that to keep the outside air from coming in. You can raise the set point, but mostly you got to deal with the kitchen.

So that way you have positive pressurization with dehumidified air right. So now, when the doors open, does the air go in? No, it goes out because you're positively pressurizing with dehumidified air. That makes sense. So, if you think about things like this, it helps you solve the.

I the the concept of why it happens in residences too people with a lot of kids who are going in and out they got a pool deck. Do you see somebody with a deck with kids in a pool deck and you've got sweat and vents? I can almost guarantee you why the vents are sweating. Why? Because the kids are going in and out don't be like that: okay, you're bad enough, as is i'm just kidding. No, when you keep the doors open, obviously moisture's going to come in and a lot of people with kids they're going to leave the doors open because they want to be able to hear them outside or leave one of the doors, cracked or whatever people with animals.

That go in and out a lot same sort of thing. You know you think those doggy doors seal well to the outside. Most of them don't right! So that's a lot of moisture so think about how's, moisture getting in reduce that and then with equipment. The ways equipment, dehumidifies, better, is colder.

Evaporative coil longer run time. All right, colder, evaporation longer run time, but if we don't have enough heat load coming in what does that do to run time? So you put radiant barrier in that makes the system run less shorter, runtime right so now that can even affect that problem. On the inside of the space, so when we're assessing inside what are the conditions, why is the humidity high in here right? Two? Is the system running enough? Is it sized properly did something change in the structure that decreased the loads and then third, is the evaporative coil getting cold enough? You see that's counterintuitive, because a lot of times when we're trying to keep vents from sweating we're like well, let's d: let's increase the air temperature coming out to make the vent warmer, so it doesn't sweat. But what did we do to space conditions when we did that we increased our indoor relative humidity, so when vents are sweating? Yes, obviously, if you've got a freezing, evaporator coil, a super dirty filter that kind of stuff yeah address that you got to look at all your airflow indicators, dirty blower wheel, all that, but again when that happens, when you've got a cold coil, that's going to actually Dehumidify, the space more so you got to think about.

You know: why are we losing control of humidity in this space with a system? That's dehumidifying really well old, crappy dirty units, dehumidify really well again bad on power, but a lot of times. Power, consumption and dehumidification are in conflict with each other and we got to remember that when we're having conversations with our customers, if you want to dehumidify a house really well then have nice single, pane horribly. You know radiant transmitting windows, that let a lot of sunlight in have a really hot attic seal. It up seal the house really good, but let a lot of heat get in so sealed so that air can't get in, but not insulated, very well, so that heat can get in right.

Well, that's counterintuitive! That doesn't make any sense! Well, guess what your unit's going to run a lot right and when a unit runs a lot that dehumidifies better. So it's about sealing that reduces moisture. Insulation is only for heat, so anytime, you've got a moisture problem and you're tempted to do something with adding insulation check yourself, because you're going to make it worse - and i know i've done it like a thousand times i've taken in - and you know, heaped insulation over The top of vents to try to keep them from sweating on the bottom side, which guess what that does the opposite, it makes them sweat more sealing is what you should focus on when you have vent sweating to make sure attic air isn't coming in around that Kind of thing, so again, when you see moisture, think sealing think heating, not cooling, heat things in order to reduce moisture seal them to reduce moisture, don't insulate them make sense. You all get a take away from that.

Hopefully some of you are falling asleep, that's fine! I understand all right, thank you all have a great week, 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 you.