Hey thanks for watching in this video we're going to talk about a category of problems that can really be quite serious and that is moisture issues on vents on ducts and on equipment. And so we see this as condensation, often we'll call it sweating ducts or a sweating vent, and the reason it's serious is because when you have condensation build-up, not only is the moisture in that location, a problem, because you can get some growth there, but it also Often represents a bigger humidity problem or a bigger, moisture problem that can lead to a lot of respiratory concerns. If you take a look at this chart, it shows that, within the conditioned space, we really want to keep our relative humidities between 40 and 55 percent. If we can, if at all possible, it creeps up into the may, be the low 60s that can be okay, but once we get any higher than that, that can be a challenge.

Not only do we want to keep things from condensating because that causes issues with growth, but we also want to think about the condition space and make sure that we keep our humidity under control. So again, we're gon na talk about three primary areas: sweating vents, sweating, ducts and then sweating equipment and, let's start with sweating vents, because that's the one that has the most to do with what's going on in the space itself. And so the reason why a grill or event diffuser, whatever you want to call it is gon na sweat, is because the temperature of that grill or diffuser or vent is hitting the dew point of the air. So there's really three different categories of things that can cause this problem.

The first and the easiest to fix is that you have humid air intrusion around the vent itself. So the first thing I suggest is remove the vent, look up inside and see if you can seal inside of that boot or can or whatever you happen to call it in your part of the country, see if you can seal around that area to prevent moist Air from making it in around that vent - and so that's a really easy and common thing. Sometimes you can use something like foam tape in there or maybe a little silicone or a little bit of acrylic latex caulk, maybe even a little mastic on the top side of that boot. You can seal that to the drywall or to the floor depending on.

If it's a floor or a ceiling vent, but a lot of times that will help solve that problem. If that is already taken care of, and you don't have issues with moist air intrusion around it. Well now you have to think about the temper of the vent, and you have to think about the dew point of the air in the space first thing to remember is that dew points can change as that air creates Stratus within a space. So if you have a really really high ceiling and that vent is sweating up at the ceiling level, you may have a different dew point air and down at the bottom, and that's something that sometimes you can solve with things like D stratification fans.

In order to help mix that air, so ventilation can help in some situations, but more than anything else, in order to prevent sweating vents, we really need to control the humidity in the space, and so, if you're, seeing relative humidities that are creeping up above fifty five Percent then the first thing to do is to control the humidity in the space. Now the tricky thing is is that in many cases, running lower fan, speeds running lower blower speeds, running less CFM over that of a protocol will result in colder air which will result in a lower temperature vent, which we tend to think. Well, that's gon na cause. More sweating, but also when we run lower air flow over that evaporator coil, more moisture, is removed from that air.

Therefore dropping the relative humidity in the space. It's something that we call sensible heat ratio or SHR when we run lower airflow over an evaporator coil. If the piece of equipment is functioning, the same meaning you're moving the same amount of refrigerant, then you're going to dehumidifies the air more because you're gon na have a colder coil, thereby changing your sensible heat ratio, meaning your sensible heat ratio is going to drop, sensible Heat is the change in temperature and latent heat removal is the moisture extracted from the air so, in other words, we're going to remove more latent heat by the equipment when we run lower fan speeds. But in a lot of cases, technicians are gon na go to a situation with a sweating vent and they're going to try to increase the fan speed and why are they gon na? Do that? They're gon na? Do that because they want to warm up the vent itself and that will result in warming up the vent when you run higher air speeds, you have higher air velocities higher air velocities means that you're gon na have warmer air and so by running warmer air.

A lot stands to reason that you're gon na have a warmer vent, but the problem is in doing that. You solve it on one side of the equation by warming up the vent, but you cause more of a problem on the other end, because you don't dehumidifier as well and in order for us to solve this problem, we have two ways of solving it: either reduce The humidity in the space, while keeping the vent temperature, essentially the same or warming up the vent temperature, while keeping the relative humidity in the space, essentially the same. My approach is to really approach it by reducing that relative humidity in the space. If the relative humidity is the problem which, generally speaking, that's what you're looking for so it's things like having a space that has high relative humidity, maybe because overall, the system is sized improperly it's oversized, so it's short cycling and not dehumidifying, or maybe you have customer Who's opening the doors into the space during cubed times, and so a lot of air is getting in that way.

Maybe they're cooking a lot in that area and so there's a lot of moisture from there. That's not being ventilated with a proper kitchen exhaust or maybe it's being recirculated into the space, or maybe they have something like a lot of cann lights, going into an unconditioned attic where that moist humid air is in filtrating into the space due to air leakiness. So you want to look at air leakage. You want to look at.

Are they running ventilation properly? Are they opening doors, all those sorts of things and a really great way to help solve this problem? Is a first? Do a blower door test to see how leaky is the space and there's a couple different techniques there if you're not familiar with how to do a blower door, that's a whole different video and we've done some of those videos as well. A couple of really great resources for learning more about that is looking at manufacturers of blower doors like retro tech and the energy conservatory, and then also Nate Adams. My friend Nate Adams has done a lot of really great discussions on this. We also did a podcast with geo meta in the past, where he talks about blower door.

So if you want to learn more about that, but what the blower door helps you learn is: is the space nice and tight, because when you have very leaky spaces, you're gon na tend to have more moisture, so that leakiness is a really big factor and moisture. Making it into the space so, when you're dealing with an issue of a sweating event, it's much easier to address it by keeping the moisture from getting into the space in the first place through proper ventilation and proper air sealing than it is to try to get It out, but if you've got no choice well, then you have to look at either. Resizing equipment may be adding dehumidification and maybe adjusting your settings on your equipment depending on the type of equipment that it is. But just know that if you reduce air flow going over that evaporator coil, you will dehumidifier, but you're still gon na have a colder vent and so now you're kind of in the same situation.

So generally, just changing fan speed on AC equipment usually isn't going to solve the issue of a sweating vent. But again it comes down to the dew point of the air and the temperature of that vent. If that vent hits that dew point temperature, then it's going to sweat a couple different devices that I suggest using to measure dew point, because a lot of people don't even know how to do that. My favorite is the psychrometer that comes in the field piece, JobLink kit, that's what we use most often that's a great psychrometer.

You can use the field, peace app or the measure quick app in order to get a relative, humidity, wet, bulb and dew point. You can also use the test. Oh 6:05. I, if you're using the test - Oh app, as shown in this screenshot here from the test - Oh app, it says TD and a lot of people, don't know what that is.

That is temperature dew points, so that TD means dew point. So that's an easy way for you to do it and then also uei makes it as part of their Hub 6 kit as part of their hub kit. They also make some really nice, AI kilometers, that you can use, but regardless in order to see what dew point is in a space, you have to use a good quality psychrometer. You have to let it acclimate to the space humidity and that's one of the really big starting points before you start diagnosing and figuring out exactly what to do.

First see where your relative humidity is in the space and then you can look at things like your. Maybe your vent surface temperature. Now that can be tricky to measure. Sometimes you can use an infrared thermometer if you get right up against it to measure the surface temperature of that vent.

But now you have to know a little bit about emissivity and all that and you have to know how to properly use infrared or thermal imaging and that's another skill that you need to. You can't just jump into it. You have to understand how that works or the way she'll get incorrect readings. But again, what we have to do is either control the temperature of the vent or control that relative humidity in the space and generally controlling the relative humidity in the space is your best bet.

Item number two is sweating ducts in an attic and so sweating ducts. In an attic is a completely different category of problem of attic, crawlspace basements, especially if those spaces are unconditioned or they're conditioned differently than the rest of the house, our insulation, currently in the attic we are at a seventy seven point, seven degree dew point. So any surface that gets below seventy seven point. Seven degrees will start to sweat.

So you know that air and the ductwork is, you know, gon na be 48 degrees or so and insulation r-value ductwork just isn't meeting it. So we kind of have two options: decreased, dewpoint or increase insulation going down into a cell down here, okay, so this addict has Ison along the top. They repented the top plates here, which of those shouldn't be vented, and then this space in the Attic needs to be controlled climate-controlled. So we need to determine if I and control the temperature in this space, but multiple Ridge vents they cut out, which is a really really poor design, given the fact that we're icing into everywhere here we have a five ton unit for upstairs a bypass damper based On static one zone here goes and feeds the master, suite and closet, bathroom, etc.

Our other zone comes off here and feeds the rest of the upstairs really high humidity. Upstairs I'm gon na get a in the Attic here. You can see we're coming sitting a bit here. Our units compensating sweating our secondary pans building up, and this is high high humidity up here.

Alright. So here we have an air handler inside of the attic, obviously ductwork inside of the attic as well. What we were experiencing was the unit would sweat so aggressively, because the cabinet itself was hitting dew point that the secondary pan would actually fill up with water periodically. Also ductwork, the exterior of the ductwork due to the high dew point, was also sweating pretty much everywhere.

What we did has we have i singing throughout the attic, so this is now a sealed attic. We use the ultra air s d12 dehumidifier in this particular application, and so it has a slight cooling factor to it, as well as incredible dehumidification ability. Currently, our relative humidity is 40 % and we are 71 degrees in the attic space. So this cabinet, this is the infinity series carrier.

So it's running in low speed, dehumidification! That's usually when you see the most issues as far as equipment, sweating or ductwork sweating and there's absolutely no moisture anywhere on ductwork on the equipment and this whole entire attic feels incredible again. We have ice anine throughout the attic. Sealing off all the vents, any porch areas and then no insulation, so all the insulation that was on the drywall traditionally got removed working amazing. So when you have situations like the video shown where you have ducts that are sweating in the attic there's two factors: there's the temperature of the surface of the duct itself and then there's the dew point in the attic.

It's not the temperature in the attics, not the wet, bulb temperature. It is the dew point in the attic, and one thing that you'll find often is that as an addict gets hotter, often the dew points get quite high, even if the relative humidity percentage is low. So, for example, I'm using the it's called the psycrow degree F app. That's way.

I know how to describe it, but I use this all the time in in place of using a psychometric chart just makes it nice and easy if you plug in a hundred and thirty degree, attic temperature, which is something we see in Florida. Quite often, even if you have a thirty five percent relative humidity in the ad in that attic, that is a dew point of ninety three point: five degrees Fahrenheit, which means that any surfaces in that attic they get two. Ninety three point: five or below are gon na start condensating and that's very easy for supply duct work to achieve that now, there's a couple different techniques you can use to solve this issue. You can use higher r-value supply, duct work or maybe rapid in something, like you know, double bubble's, some sort of uh, some sort of another insulation on top of that insulating properly is super important, and so, if you have gaps and insulation, obviously those will condensate water.

As that surface hits dew point a better way to deal with. This is to drop the dew point in the attic, and you can do this through ventilation in some cases. It's worse, if you have a sealed, moist environment - and this is especially made worse if things like dryer vents are leaking in the attic or venting into the attic, heaven forbid or bath fans are venting or leaking into the attic or kitchen exhaust. So that's something I always look at first, when I go into an attic that has any condensation in it, especially on the ducts, is, is moisture being added to this attic in some way, and then I look at.

Is it vented or unvented and if it's vented, but it's poorly vented, sometimes venting it better, can help a little bit when it comes to keeping that dew point lower because you better communicate with the outdoor air? Now I do not suggest using power vented attics and the reason why I don't is because, when you power vent in attic, you create negative pressure in the attic and often that will draw air from inside the house into the attic space and actually reduce the efficiency Of the home now this all comes down into you know, knowing your blower door number, knowing how leaky or tight your home is, and so there's some other factors here. But you definitely want to make sure that your attic is if it is a ventilated, attic and needs to be properly ventilated. Sometimes the only option to solve. The problem, though, is to seal the attic to make it into a non-ventilated attic, which is where you use.

Foams, like open cellar, closed cell phones, often called Ison een is a trade name for that, and so you seal the attic and then you D, humidifying condition the attic that's where we recently used an SD 12 from ultra air and a high-performance install that we did And we use that in order to dehumidifier and cool the attic slightly in order to bring it into the conditioned space and that dealt with that problem that you saw in that video from Jessi, where all the ducts were sweating. By sealing up that at it completely doing it properly and then conditioning it now that whole problem went away and the relative humidity and the attic came down, and also the relative humidity and the space came down, because if you have an attic that is leaky to The occupied space, but you seal it to the outside, and then you condition it really well with dehumidification, if you're in that type of market. That requires that, then that's also a great solution. It's it's a pricey solution, but it's a nice long-term solution.

That's gon na! Do a really good job of taking care of the problem. So when you have sweating ducts, your only options are: can you in some way increase the surface temperature of the duct, which you could also do by increasing air flow? But that is a dangerous equation, because when you increase air flow, especially when you already have a humidity problem now you reduce the ability of the air conditioning equipment to dehumidified and no matter what you do. Your air conditioner is probably gon na, be the best dehumidifier in your home as far as the amount of moisture that it can remove really good dehumidifiers are still often not gon na remove as much moisture as the air conditioner they're just gon na. Do it all the time and so properly sized air conditioning equipment help solve a lot of these problems, but again, when you reduce air flow, that's gon na create colder air inside the duct.

You're gon na have a lower velocity through the duct, which is going to create cooler, surface temperature on the duct. So if you have a situation where the system does have low air flow, this is the other side of this equation. If your system has low airflow because the duct system is installed improperly or it has a dirty of a protocol or a dirty blower wheel, or something like that, then that can sometimes be a fairly easy fix. You fix that air flow problem increase the airflow and then the surface temperature of the duct will warm up and it may stop sweating, but that's we're looking at the surface temperature of the duct as you can and looking at that attic dew point: that's where I Would always start whenever you have anything sweating in an attic or in a crawlspace or in a basement.

I often talk about addicts because in Florida that's what we've got. That's the place. You start is look at that dew point. Compare that to the temperature of the air in the duct and see what's going to be easier, is it gon na be easier to drop the dew point of the air in that attic or crawl space or basement, or is it going to be easier to somehow Warm up the surface of those ducts, quick pro tip here.

You're often gon na see the worst problems with sweating ducts in attics that are pretty well sealed, pretty well insulated and have some sort of radiant barrier and the reason is is because moisture tends to get trapped in those attics. So you have high overall moisture content and grains high relative humidities and low attic temperatures. When you have that low attic temperature. Now you don't have as much heat that's conducting into the duct itself and so that surface temperature gets cooler.

So now you have that kind of prime condition for sweating. On the surface of the duct, often really hot attics that are well ventilated. You won't have sweating ducts just because that heat conducts into that outer jacket of the duct itself, keeping it a little bit warmer driving in up above dew point, and so this is why, for those of you who have worked in hot humid environments like Florida for Years and most of your duct systems, don't sweat, older equipment, most sure duct systems aren't sweating all the time you may have some areas where the insulation is compressed, that they might sweat a little bit but generally they're, not sweating. That's because you have this very hot.

A very well ventilated, attic that now is actually heating up that surface jacket of the duct itself, keeping it above dew point it's often when we try to make things more energy-efficient when we're running lower fan speeds in order to dehumidified better in the space, you can Have these cases where the space itself inside the building is 50 percent relative humidity, but all the ducts and the Attic are sweating like crazy and that's why, when you have high-performance homes, I pretty much always suggest sealing up the attic bringing the ductwork into the conditioned Space by D humidifying that attic and now that kind of solves that problem, the final one that we see a lot in Florida is, we see sweating equipment. Now in Florida we generally have fan coils. We don't have a lot of furnaces, but same thing is true. In furnaces a lot of times, they'll take this equipment and they'll put it into a closet in an unconditioned space like, for example, a closet in a garage or even a closet in an area that may be conditioned, but it's not maybe kept as well conditioned.

Maybe a laundry room or something like that. Often these rooms will have gaps and cracks into the attic or maybe into the crawlspace. If that's where you are, and those gaps and cracks act as a gap for moisture to come up through those spaces. So, whenever you're putting an air handler in a closet or something like that, you need to make sure it's well sealed.

Now. Obviously, if you're, installing a furnace and 80 % furnace that has to communicate with the outside and so now kind of all bets are off. How are you gon na solve that problem, and so now you need to just make sure that it's as well-ventilated as you can. This is why, in Florida, though, we do see units wet and garages.

Sometimes we see the worst sweating, the worst condensation and enclosed spaces, because what occurs is is that moisture is allowed to get into these enclosed spaces? It gets trapped and then that air handler or coil radiantly cools that entire room, often that will create cold walls. That will then also condensate and build up growth. This is where sometimes you'll remove an air handler and you'll notice that there's all this growth right behind the air handler where it was next to the wall, and that's because that air handler is radiantly cooling, that wall dropping it below dewpoint and causing that moisture, and That growth, what I often suggest, if you're gon na, have them in enclosed spaces like this seal it off insulate it and condition it that's a better way, add a little return. Add a little supply better, yet use dehumidification, I'm a big fan of supplementary dehumidification, because then you can do it year-round, but in some way dehumidifier and control.

The dewpoint in this just remember that when we ventilate were stuck with whatever the outdoor dew points are, and in Florida we often have outdoor dew points that can reach 80 degrees. That's a very high dew point. That means anything under 80 is going to condensate, and so you really want to think about what your solution is gon na be. Is it ventilating better, so creating more ventilation more air to the outside, which could potentially have AI dew points, or is it better to seal insulate in condition and often ceiling, insulating and conditioning? Is the better is the better thing, but first always start with that? Sealing part that air sealing is often the solution, just like we mentioned with the sweating vents.

When you have that moisture, that's traveling and around the vent around the boot that can cause that vent to sweat, which is a big problem by controlling dewpoint inside the conditioned space and the relative humidity generally to that sort of in cooling mode 75 degrees. At 50 percent relative humidity, which equals 55 dew point, that's sort of the ideal condition for most people. Sometimes they wanted a little cooler than that, so that dew point may drop a little bit, but that 55 degree dew point is kind of a sweet spot. When you get into attics, that's often unrealistic, if you condition them with dehumidification such as the SD 12, you can.

You can often get to that level. I'm you may not always be able to, but you still want to keep those dew points as low as you can get them anywhere that you're gon na have cold surfaces like ducts vents. Anything like that to prevent that condensation for some of you who are in arid environments, you know we call these areas, you know that have desert, they have sand outside, rather than green grass. None of this applies to you.

You don't have to worry about. Hardly any of this because you just don't have those sorts of conditions. You have very low dew points year-round, but when you're in other markets even places like Ohio, you have seasons where you get high dew points and that's where you have to think about and control these factors again surface temperature. We can control in some cases, but often the best bet is to control the dew point of the air.

Hopefully that was helpful thanks for watching we'll catch you on the next one.