Awesome tips Bryan and Jesse. This sweating seems to be more of an issue than it used to be with the lower efficiency units. Also, slowing the blower speed seems counter-intuitive but makes perfect sense. Thanks!
I agree totally and i think the newer coils and txv valves in their pursuit of ultra efficiency are causing it ! How ? The subcooling charge is critical and most installs are not vacuumed and charged correctly ! Why ? Greed and push for time and poorly trained techs, installers !
These kind of videos are priceless to help to UNDERSTAND. I changed my mind months ago with one great piece of advice of Bryan: Forget RH, seek for Dew Point. Everything is more easy now (here in East Coast of Spain we have the same battle with condensations). Thanks again HVAC & R School. 👍
So the moral of the story is you're rarely going to fix this problem unless you remove the equipment and prep the space, equipment and ductwork like mentioned. Alternatively make sure the contractor specs the space to be conditioned prior to new equipment. Very nicely done video and thank you for all the time you spend preparing these.
Great educational video! Thank you! I would add one solution of sweaty grills that I had to used a few times this 2020 summer. So, brand new 10 ton Trane package rooftop unit and supplies were sweating like crazy.... Turns out that it had only 3 return ducts 14’ each. Pretty much a half of the return it should have! For supply it had 4 16’ flexes.... So, I just added 2 14’ returns and the problem was solved. Now, after watching this video, I know that I’ve increased the supply air temperature by adding adequate returns :) Thank you one more time!
Well done sir, the more you get into hvac you realize know body knows for sure but who is the smartest in the room suggesting goes as fact based on theory 🤔. Temperature pressure relationship is an exact science. Sizing and troubleshooting is hypothesis based on that,no one gets it perfect, too many variables.
That was incredibly helpful. I’ve got an evap coil that’s sweat a little bit and I was thinking I needed more air and as you pointed out less air is correct and it’s in a closet that’s semi conditioned but also has some holes where pipes and wires are going through the wall to the laundry room. So I’ll seal up the holes and go back to a little less air to the evap coil. 🙏it works
I hear mostly about attics & crawlspace, but what about 2 story homes with the ducts between the floors? 1st floor vents on ceing & 2nd floor vents on floor. I had to replace a 12ft long hallway ceing because of water damage from sweating ducts. Now with the summer heat in Tennessee, my new ceing is dripping water. The ducts were not insulated because I guess they didn't need to be since they were in between 2 conditioned areas. (Built in 1987) We chose to wrap them. Bad idea? Good idea? I don't know. So now I'm looking to see what will be the method for best results. Get it redone & go thru attic & crawlspace, or just take out ceiling & update as needed? Any advice? Thanks in advance.
Not on ducted mini splits. Tried it both ways and higher fan speed is all that worked to stop sweating grill. This I found was due to the VRF technology. Slower fan speed caused coil to get colder slowing down refrigerant flow causing. Same denhum as higher fan speeds. If you have any other suggestions for when this happens on ducted mini splits, I would greatly appreciate your suggestions.
Great video Bryan , super informative with a means of a resolution, Thank you so much for sharing you are outstanding, I just wish you did some real time troubleshooting videos, again great stuff and thank you.
I have a commercial building in very hot very humid region . The design is providing humid air via fresh air fans without any means of cooling or drying . It just pumps the humid outside air into DX Concealed FCUs plenums. The result is vents are sweating, relative humidity is high …
I had an issue with a customer's main plenum at the air handler and the plenum running across the floor joists sweating in the small unfinished area of his basement. There was no water staining or signs of sweating in the HVAC soffits of the finished areas of the basement. The unfinished furnace room doesn't have a supply and didn't have any pass thru grills, the HVAC contractor has installed two pass thru grills to the finished areas to try to eliminate the problem. It did not. The dew point of the room was 59.7, RH was 62.4%, air temp of the room was 73.2F, the air temp inside the supply plenum was 54.6F and the plenum surface temp was 64F. Would you have any ideas on how to correct the sweating plenum and why this is happening? Thanks so much for this video.
Ok great video. Can I ask a question. We have our air handler in the attic. The supply to and return from the first floor are both in an old chase way about 3x2 feet running from attic to first floor ceiling. We’re getting condensation pooling and causing damage in the first floor dropped ceiling Hvac soffit supplied by that line. Went into attic. Found chase way between attic and first floor. Chase way is probably a 3’x2’ utility space running along an exterior wall. Return duct and supply duct that are sweating are in that space…. Absolutely bare. No insulation whatsoever. Isn’t it the most likely that the lack of insulation on the ducts inside this sauna-like chase way is causing the sweating that’s pooling in the first floor dropped ceiling hvac soffit and associated drywall damage?
A lot of information to digest. We live in Florida. The air handler is in a laundry room closet and we have sweating ceiling vents and possibly ductwork in the attic (we've started seeing water stains on the ceiling near where ductwork runs in the attic). The house (built in 1987) has roof ridge vents and blown insulation. We also have the dryer exhaust out the roof (I'll have to look at that). Would it be a good idea to add some additional roof venting? Added fyi, it's possible that this is the original equipment installed in the house. Thanks.
There are many people don't care about the electric bills and they keep enjoy cool to cold air inside the house. The air-ducts are sweating and leaking due to condensation. I told my friend "don't set temperature below 75 degree F." Now, I have to fix the leaking.
A lot of zone systems I find sweating is just a missing DATS sensor to stop the condenser when the air gets too cold. 🤔 Specially when the smaller zone in calling for cooling. 🤔
Just hand new heat pump unit installed, Florida, furnace in garage, and does get hot in summer, outside panels sweat, but also the filter is getting wet from so much condensation "inside" the air handler, that the inside insulation is getting saturated and then the water leaks onto the filter below. 15 seer Bryant, single speed unit, all works great except for the extreme condensation inside and outside the unit.......only a month old, my AC guys say this is normal in hot, humid areas. My old unit was 36 years old, and sweated outside panels, but not inside......I dont know if long term, all this moisture trapped and wet insulation will damage inside parts????? Any advise much appreciated.
Late to this discussion, but my son’s home has sweating vents - ducts are on the roof, exposed to direct sunlight (Southern CA), but appear to have some insulation inside of the ducts (flat roof - there is no attic). They don’t run the AC a lot as they generally aren’t home during the day. Seems to be the worst when hot outside. Will supplemental dehumidification inside of the house be helpful?
Nearly every system I have ever seen that suffrered sweating vents had one of two [if not both] problems: the conditioned space suffered from negative ventilation, and/or some jackwit upsized tonnage too much, and the a/c doesnt stay on long enough on average to dehumidify. In the case of the latter, temps drop so fast the t-stat clicks off before the space is...conditioned. They were probably chasing problem #1 to arrive at the mistake, combined with substandard insulation. If you ever want to see a bad setup... the maritime industry is littered with them: kitchens with exhaust running 24/7 and no make up air, engine room exhaust causing massive air changeout in adjacent spaces every time a door opens, etc.
Question: Recently I had a new Furnace with Acoil installed in my basement. It included new flex return and supply boxes and insulated ducts to the new equipment. The return and supply both were fed into custom insulated boxes that fed into/out of the furnace/acoil areas. Right before the installer left upon completion of the install, he took a screw driver or pencil (couldn't tell because he did it so fast) and punctured a single hole in the flex insulated box that is sitting directly before the air filter from the return duct, and punctured another hole through the insulated box wall of the box that outputs from the acoil into the supply ducting. What is the purpose of meticulously sealing the boxes and ducting with tape only to puncture the boxes with holes? I asked him after i saw him do it and he acted very sketchy and said something about using a probe to test but when I asked him if he would test those he said he wouldn't because he believed they were fine!? I like to trust technicians to do things by the book but in this case I felt suspicious he intentionally wanted to degrade the unit in some way out of spite or to ensure a service call down the line. I want to get a better sense from another professional before I call them on it. Could you weigh on on this? Thank you!
@@caru3257 Thank you for replying. I was wondering if anyone read my comment since no one commented. To answer your questions, No, he didn't cover the holes before leaving and he also didn't take any static pressure tests after puncturing the holes. I instinctively sealed both holes after the installers left but i've been wondering if he did it on purpose to degrade the unit. If the holes were left uncovered/sealed wouldn't that create a negative pressure situation in and around the furnace when the blower fan is on that could recirculate carbon monoxide back into the house?
He punched the holes in your supply and return plenum boxes so so that he could do a Static pressure test I guess just for the heck of it to test the system to see what the TES P was On this new installation but when you start asking questions he knew that would only lead to more and more questions and it's a very technical subject and he probably I guess he just didn't want to go through all that but why he didn't tape up over the holes is beyond me you should at least tape up over those holes it's all you have to do and to your question no it's not going to create another service call, possibly on the supply side the whole could create condensation issue which is what this video is all about as a cold 52ﾟ air comes out in a 130ﾟ humid attic it will create condensation around that spot possibly, I don't understand why he didn't take over those holes,. He didn't puncture those holes to create another service call he did it to stick his probes into and then conduct the static pressure test until he until he realized he didn't want to do it while you were watching, And asking questions, So he didn't do it at all.
@@acadianheatingandair3291 Thank you for your reply and explanation, much appreciated. I'll seal them up! Though I must say, to not do a test just because the customer might ask a question is not a great reason to not do the test.
Hi Bryan. Love your videos. Thank you for sharing your knowledge. Do you think the Fieldpiece digital psychrometer gives a fairly accurate measurement of indoor humidity percentage and indoor dewpoint temperature?
Exactly the video I need for a sweating diffuser. Alll other diffusers in the same room are fine. One particular diffuser sweats. I'll pull the access, add additional internal sealing, reattach the diffuser, make sure no air intrusion and add additional insulation to the flex duct. By the way. It's a chilled water system, the FCU has a single speed blower. Additionally, it's a dropped ceiling in a large building so it tends to be humid above the ceiling. Humidity is regularly 85% or above. Philippines is naturally humid.
We have condensation on the air handler and trunk in the attic in the winter when not using the a/c. The attic is ventilated, and we block and insulate the ceiling vents so the warm air does not get in the attic duct work. We have considered adding a heat coil to the unit for winter, or removing old insulation and sealing and insulating the attic with foam to make it part of our controlled environment. Can you recommend a company in North East Ohio to inspect and help with recommendations/improvements?
Hi I have mold growing around my ceiling fixtures (lights, fans) and staining around my vents, I had someone come out to check the humidity and they said it was fine. I also have an issue with the a/c cooling one part the house and not so much the other. My house is 1500 sq ft with a 3 ton unit. What do I do?
I read recently that code now allows for houses with units within the conditioned space that have duct work in a vented attic can now have buried ducts and not have moisture issues if you follow the rules laid out like; having the leakage tested to be very low, the ducts must be rapped in R13 in the south (or R8 in the north) and then deeply buried in R19 fluffy stuff.
I have run across numerous times when a contractor installs a P- trap on secondary drain to allow condensation to flow into auxillary pan should it overflows.Mostly on electric air handlers, allowing hot air from attic & possible ambient air from auxillary drain to be siphoned into Air handler causing it to sweat heavily into auxillary pan causing it to rust.i usually add a little bit of antifreeze to seal P-trap on secondary & thus prevent sweating to occur.
My HVAC had a 6 inch duct with a blower pulling air from out side in to the main ducts. South Texas humidity is horrible year round. Vents sweating from day one of new house. Rust and mold all the time
I’m having an issue with water intrusion/condensation pulling into my microwave, dryer and powder bath fan vent. This has turned into high moisture readings alongside the same exact wall where the dryer backs up to which is located next to the 2nd bathroom. Mold is growing along the wall behind the wallpaper in the adjoining room. Additionally, the downstairs ceiling has water stains in the shape of lines in 3 separate places. The builder is saying this is happening because of homeowner maintenance. However, I’ve been told that several of the neighboring units have had or are still experiencing microwave condensation/dripping, dryer condensation, moisture on all of the walls in the laundry room, and some other similar issues. I believe there is a flaw in the design but how would I prove this is the cause? These issues began shortly after moving in. I’ve had several companies out to assess. All humidity readings taken throughout the home have been normal. A/C unit is functioning normally. The fresh air damper isn’t defective. They ruled out a plumbing problem being the cause of the downstairs ceiling water marks. Need help to identify the problem to make the builder accountable for fixing their issue. Any advice or recommendations appreciated.
Im having this issue now in Houston, my attic is well insulated, i have sweaty vents and the house is at 70 humidity do you recommend removing the attic floor insulation, sealing the top and installing a dehumidifier
At 9:12 is it supposed to be R8 insulation? I realize codes are different everywhere, but wouldnt you always go thicker insulation in unconditioned space?
I live in an apartment in TEXAS, and too many times in the last 9 months it's been raining in my hallway from the ceiling AC unit. The main units (one for each apartment) are outside the building (I'm guessing they are the heat pump type since I get heat and AC from the same unit).The outside units aren't too old, but these apartments are 30+ yrs old, and I'm sure the inside wirings are old and outdated. I live on the ground floor of a building with 8 900+ sq foot apartments--4 upstairs, 4 downstairs.They keep "fixing" it, but it's a chronic problem. I'm sick of it--it's over 100 degrees outside, and the only way I can get it to stop raining inside is to turn off the AC. I work nights, and the constant intrusions of workmen trying to figure it out are seriously interfering with my sleep.
I can't believe the ridge vent was cut out. I've been in the spray foam business for 15 years and my attics rarely if never go above 83-85 F. You want a totally sealed attic and semi conditioned.
If they have spray foam up top, shouldn’t the blown in have been removed? Now air can’t properly pass through from the conditioned space down below into the conditioned space of the attic.
Hi, I've found my Mate, somone clever Thanks for all this refreshing training on humidity I'm planning to have installed an A/C ducted in my house The humidity come from the ground as well some walls If you could possibly help me to choose the A/C thanks DomIJ
So if I have an vented attic, I live in southeast Missouri in a slab home. I have air handler inside house (conditioned space) but all duct work is in attic. It’s mostly covered with brown cellulose insulation and vents are wrapped I assume r-6. Can I close cell foam spray the ductwork?
Question. This might sound stupid but what about raising the temperature in the attic? I remember reading in some book that sometimes raising the temperature of the space a little bit in order to remove the humidity is the best bet. Besides, you’re already burning energy by running a dehumidifier if saving energy is your goal. Just like trying to save the planet by using electric cars instead of petro. You destroy the landfill and contaminate the earth by extracting the precious metals or you contaminate the air by burning fossil fuel. There’s no way around the it.
Think about that for a second. You are correct. However, raising the attic temperature (I.e. what used to be the default) would cure the moisture issue, and you would lose the efficiency you gained by making the enclosure better. As one great engineer says, you take 2 steps forward for efficiency, but give one back for thermodynamics and durability. But you are still better than you were.
How about taking a diffuser in the attic with low cfm from the duct in order to lower dew temperature point and balancing the temperature in the attic with room below it.
I'm in Central Florida with the air handler in the garage. There is not a chance in hell of getting humidity down to the 40-50% range. It's straight up 80-90% humidity most of the year. My ducts on the air handler are sweating bullets and it's ruining the ducts, there is water all over the floor and the bottom and corners of the ducts. What do I do? I already have some big water damage on them.
Love this informational video. I checked your website to see if you service our area as I am a Florida resident. Unfortunately you do not serve the Tampa Bay area. Is there a company you might recommend in that area? I have a sweaty plenum and honestly need the entire duct system evaluated.
Hey Bryan, I'm a Building Scientist in Florida as well. Great video! I wanna add something for anyone in the comments that has helped me. I typically like to grab the dew point outdoors along with the attic dew point for a good comparison. Dew point in a vented attic can only, at best, be the dew point outside. If DP seems really high, but is the same as outside, at least you know the attic itself is performing well. It's a good isolation strategy. I would note that if you just use a hygrometer while on site, it's only a snapshot in time and you won't have the whole picture of what could be happening in other parts of the day. Using data loggers over a period of time are better to catch trends (putting one in the attic, in the conditioned space on each floor, one outside, etc.).
Hi Bryan I really appreciate this video, it has been extremely helpful!!! My attic is Icynene completely. When the 5 ton Ac was installed, they put 2- 6*8 air vents in the attic and a return ( not sure if this should have been done). The size of the attic is about 2300-2500 sq ft. My ac ducts leading into the house and the plenum boxes sweat like there is no tomorrow and the drips are causing mold growth. SO before I saw your video I just recently encapsulated them by buying over 50 cans of spray foam and spray them to create more insulation with hopefully preventing my sweating (condensation). #1 I do not know if this will work. If you can give me some advice, please. #2 can you highly recommend someone who knows how to deal with an attic that has been icynene and the condensation problem I am having. Someone from Miami or nearby areas that is. I have called mountains of companies from high end to low end and they do not know what the heck I have in my attic. To them, it’s the strangest thing, and unsure if having ac vents in the attic is the ideal thing or not so they can’t give proper recommendations on how to solve my problem. I even just recently called one company and asked about the Dehumidifiers and they were not sure about adding one. Running into your video has been a bit of a blessing because it’s exactly the problem I am having. I would appreciate your feedback and recommendations. Thank you and stay safe. --
My attic has something similar. With sweating on the box no water in the secondary pan. But inside of my home the humidity level shows 70%. My a/c is at 70 degrees. The condensation is on the box that leads to the ducts. How can I get this fixed. I had my home built in 2014. Some bedrooms are not all that cold.
I just opened up my furnace and I immediately see rust and water spots inside of it.. my furnace & air handler is in an upstairs closet. When I looked in the closet the other day, I saw condensation on the refrigerant lines (I believe that's what they are? 2 copper pipes leading into where the evap coils are).. is being In a closet causing this? Or what other issue might be causing this? I started looking into this because I'm getting high humidity(nearly 70%) in house & my a/c seems to be running almost constantly.
Thank you this video I have 4 large units one unit has been sweating badly causing the alarm system to act up I'm thinking it's a fam speed due to the belt needs replaced causing fan speed to slow
Good video. If i may ask a question,my new replacemnet ac is the same size as the old one. The instalation looks very maticulous,with low fan speed the evaporator coil will freeze . The ac tech, raises the fan speed to increse temp. At evaporator coil and the pressure is now 40psi instead of 30psi. The fan is so loud its unbelievable. It has a 2 speed fan motor, low speed is quiet like the old unit. He resurched the motor and foundered settings inside the motor cover, which was only marginally better. I asked if he could raise the setting on the exspansion valve so the temperate in the evap.coil would be above freezing.he said it is not adjustable and would not work well. He said the unit is too large. the old one which was installed very poorly, ripped ducks, you name it,but did not freeze and had multiple fan speeds.the home is 95 years old and only insulation in the attic foot, 6 inches. Thank you ,tim
Yea i had sweaty vents, i pull it off and you can easily see a finger nail gap on the boot. This solved my sweaty vent problem. Now i need to figure out why the light switch bracets have a water ring around it and the middle hallway of my house where the wall meets floor is sweating too. I live along the South Texas coast so yea March-Oct are the worst months of the year. Wierd how this problem literally happend after Harvey so i dont know if my house shifted or something with no damage to the outside whatsovever.
With the infinity system in the attic and system and ductwork were sweating in dehum mode. Should the ductwork be sized for the 1st or low stage compared to maximum out put to prevent sweating?
I am Having this issue in my 2 floor home. Water is inside the ducts and they tell me that I have yo change all ducts (11 vents). Ig is extremely expensive and I wonder if it is necessary?
You are either getting warm air in your ducts or It it is really humid outside your ducts in the attic causing them to sweat. Higher r-value flex may help but to me this is a symptom of high dewpoint like Bryan is saying
I plan on building a house when I sell the one I’m in and would desperately love to end up with an AC system that actually works and doesn’t end up with the sweating ducts I have lived with my entire life here on the east coast of FL.
Because even if you use R 8 or whatever higher R value duct in what they dont tell you is that it breaks down over time and the way they stack the insulation at supply houses it never has the R value promised ! Oh yes the ducts might be 2 inches thick but the insulation in the ac units isnt !
When you conditioning a space.. say you want that space at 72. The air blowing out of the vents has to be at 52. Sweating is a product of ducts not insulated. To attics not being ventilated properly hence a fan. Soffit vents with ridge vent does NOT work unless you sustain 10-15mph winds all the time. Sealing ducts helps too! There are many many factors. Also what is the insulation value for the duct? What is a the insulation value for the run outs? There is more of a science to HVACR than average people think about.
Point of the entire sweating issue is its in the attic ! Stop putting units and ducts in 150 degree attics ! Put them inside the envelope of the house . Spray foam should be mandatory for all homes ,trust me it works and will cut your electric bill way down ! Stop letting contractors shove units in hot attics so the can sell more square footage !
Awesome tips Bryan and Jesse. This sweating seems to be more of an issue than it used to be with the lower efficiency units. Also, slowing the blower speed seems counter-intuitive but makes perfect sense. Thanks!
I agree totally and i think the newer coils and txv valves in their pursuit of ultra efficiency are causing it ! How ? The subcooling charge is critical and most installs are not vacuumed and charged correctly ! Why ? Greed and push for time and poorly trained techs, installers !
Great information.
Also, the charge adjustment is important , superheat for pistons and subcooling for TXVs.
Good luck, everyone!
These kind of videos are priceless to help to UNDERSTAND. I changed my mind months ago with one great piece of advice of Bryan: Forget RH, seek for Dew Point. Everything is more easy now (here in East Coast of Spain we have the same battle with condensations). Thanks again HVAC & R School. 👍
So the moral of the story is you're rarely going to fix this problem unless you remove the equipment and prep the space, equipment and ductwork like mentioned. Alternatively make sure the contractor specs the space to be conditioned prior to new equipment. Very nicely done video and thank you for all the time you spend preparing these.
Great educational video! Thank you! I would add one solution of sweaty grills that I had to used a few times this 2020 summer. So, brand new 10 ton Trane package rooftop unit and supplies were sweating like crazy.... Turns out that it had only 3 return ducts 14’ each. Pretty much a half of the return it should have! For supply it had 4 16’ flexes.... So, I just added 2 14’ returns and the problem was solved. Now, after watching this video, I know that I’ve increased the supply air temperature by adding adequate returns :)
Thank you one more time!
Well done sir, the more you get into hvac you realize know body knows for sure but who is the smartest in the room suggesting goes as fact based on theory 🤔. Temperature pressure relationship is an exact science. Sizing and troubleshooting is hypothesis based on that,no one gets it perfect, too many variables.
That was incredibly helpful. I’ve got an evap coil that’s sweat a little bit and I was thinking I needed more air and as you pointed out less air is correct and it’s in a closet that’s semi conditioned but also has some holes where pipes and wires are going through the wall to the laundry room. So I’ll seal up the holes and go back to a little less air to the evap coil. 🙏it works
Glad it was helpful!
Thanks for this video! I have this problem. Attic is vented but now sweating for the first time.
I gotta say again jesus! Your videos a fantastically educational. Great job.....again thank you.
very informative and helps me a lot having issue now with duct sweating and vent sweating and my FCU was place on the attic.
That was a TON of great info. Thanks so much.
You are so welcome!
Yeah great video. I see this often in texas. Mostly vents sweating inside the home. The boots also must be insulated well.
Customer: Is this mold?
Me Grinning : Nah... that's GrOwTh
Benjamin Hancock I laughed out loud. Omg, I have to say this every day
Good stuff. Wet duct calls are the best.
I hear mostly about attics & crawlspace, but what about 2 story homes with the ducts between the floors? 1st floor vents on ceing & 2nd floor vents on floor. I had to replace a 12ft long hallway ceing because of water damage from sweating ducts. Now with the summer heat in Tennessee, my new ceing is dripping water. The ducts were not insulated because I guess they didn't need to be since they were in between 2 conditioned areas. (Built in 1987) We chose to wrap them. Bad idea? Good idea? I don't know. So now I'm looking to see what will be the method for best results. Get it redone & go thru attic & crawlspace, or just take out ceiling & update as needed? Any advice? Thanks in advance.
Not on ducted mini splits. Tried it both ways and higher fan speed is all that worked to stop sweating grill. This I found was due to the VRF technology. Slower fan speed caused coil to get colder slowing down refrigerant flow causing. Same denhum as higher fan speeds.
If you have any other suggestions for when this happens on ducted mini splits, I would greatly appreciate your suggestions.
Great video Bryan , super informative with a means of a resolution, Thank you so much for sharing you are outstanding, I just wish you did some real time troubleshooting videos, again great stuff and thank you.
outstanding Video, very informative. I found all of what I was looking for
Glad it was helpful!
I have a commercial building in very hot very humid region . The design is providing humid air via fresh air fans without any means of cooling or drying . It just pumps the humid outside air into DX Concealed FCUs plenums.
The result is vents are sweating, relative humidity is high …
I had an issue with a customer's main plenum at the air handler and the plenum running across the floor joists sweating in the small unfinished area of his basement. There was no water staining or signs of sweating in the HVAC soffits of the finished areas of the basement. The unfinished furnace room doesn't have a supply and didn't have any pass thru grills, the HVAC contractor has installed two pass thru grills to the finished areas to try to eliminate the problem. It did not. The dew point of the room was 59.7, RH was 62.4%, air temp of the room was 73.2F, the air temp inside the supply plenum was 54.6F and the plenum surface temp was 64F. Would you have any ideas on how to correct the sweating plenum and why this is happening? Thanks so much for this video.
Ok great video. Can I ask a question. We have our air handler in the attic. The supply to and return from the first floor are both in an old chase way about 3x2 feet running from attic to first floor ceiling. We’re getting condensation pooling and causing damage in the first floor dropped ceiling Hvac soffit supplied by that line. Went into attic.
Found chase way between attic and first floor.
Chase way is probably a 3’x2’ utility space running along an exterior wall.
Return duct and supply duct that are sweating are in that space…. Absolutely bare. No insulation whatsoever. Isn’t it the most likely that the lack of insulation on the ducts inside this sauna-like chase way is causing the sweating that’s pooling in the first floor dropped ceiling hvac soffit and associated drywall damage?
A lot of information to digest. We live in Florida. The air handler is in a laundry room closet and we have sweating ceiling vents and possibly ductwork in the attic (we've started seeing water stains on the ceiling near where ductwork runs in the attic). The house (built in 1987) has roof ridge vents and blown insulation. We also have the dryer exhaust out the roof (I'll have to look at that). Would it be a good idea to add some additional roof venting? Added fyi, it's possible that this is the original equipment installed in the house. Thanks.
Great Job on that presentation.
There are many people don't care about the electric bills and they keep enjoy cool to cold air inside the house. The air-ducts are sweating and leaking due to condensation. I told my friend "don't set temperature below 75 degree F." Now, I have to fix the leaking.
What causes just the air handler to sweat in the attic. No duct work is sweating just the air handler? Thanks.
A lot of zone systems I find sweating is just a missing DATS sensor to stop the condenser when the air gets too cold. 🤔 Specially when the smaller zone in calling for cooling. 🤔
Please show us how to check all static pressure in a furnace in the closet 😃
Just hand new heat pump unit installed, Florida, furnace in garage, and does get hot in summer, outside panels sweat, but also the filter is getting wet from so much condensation "inside" the air handler, that the inside insulation is getting saturated and then the water leaks onto the filter below. 15 seer Bryant, single speed unit, all works great except for the extreme condensation inside and outside the unit.......only a month old, my AC guys say this is normal in hot, humid areas. My old unit was 36 years old, and sweated outside panels, but not inside......I dont know if long term, all this moisture trapped and wet insulation will damage inside parts????? Any advise much appreciated.
Excellent explanations, great video!
Thank you!
THANKS!!! Now I know how to explain all the vents I've had sweating in bathrooms & laundry rooms!! 🤔💪👍👌🤘🤞👊 I mainly do new construction. 👍🚧👷
Set your temperature above comfort zone, 75 degree.
Late to this discussion, but my son’s home has sweating vents - ducts are on the roof, exposed to direct sunlight (Southern CA), but appear to have some insulation inside of the ducts (flat roof - there is no attic). They don’t run the AC a lot as they generally aren’t home during the day. Seems to be the worst when hot outside. Will supplemental dehumidification inside of the house be helpful?
Nearly every system I have ever seen that suffrered sweating vents had one of two [if not both] problems: the conditioned space suffered from negative ventilation, and/or some jackwit upsized tonnage too much, and the a/c doesnt stay on long enough on average to dehumidify. In the case of the latter, temps drop so fast the t-stat clicks off before the space is...conditioned. They were probably chasing problem #1 to arrive at the mistake, combined with substandard insulation.
If you ever want to see a bad setup... the maritime industry is littered with them: kitchens with exhaust running 24/7 and no make up air, engine room exhaust causing massive air changeout in adjacent spaces every time a door opens, etc.
Question: Recently I had a new Furnace with Acoil installed in my basement. It included new flex return and supply boxes and insulated ducts to the new equipment. The return and supply both were fed into custom insulated boxes that fed into/out of the furnace/acoil areas. Right before the installer left upon completion of the install, he took a screw driver or pencil (couldn't tell because he did it so fast) and punctured a single hole in the flex insulated box that is sitting directly before the air filter from the return duct, and punctured another hole through the insulated box wall of the box that outputs from the acoil into the supply ducting. What is the purpose of meticulously sealing the boxes and ducting with tape only to puncture the boxes with holes? I asked him after i saw him do it and he acted very sketchy and said something about using a probe to test but when I asked him if he would test those he said he wouldn't because he believed they were fine!? I like to trust technicians to do things by the book but in this case I felt suspicious he intentionally wanted to degrade the unit in some way out of spite or to ensure a service call down the line. I want to get a better sense from another professional before I call them on it. Could you weigh on on this? Thank you!
Did he cover the holes before leaving? I take static pressure and then cover both holes I drill.
@@caru3257 Thank you for replying. I was wondering if anyone read my comment since no one commented. To answer your questions, No, he didn't cover the holes before leaving and he also didn't take any static pressure tests after puncturing the holes. I instinctively sealed both holes after the installers left but i've been wondering if he did it on purpose to degrade the unit. If the holes were left uncovered/sealed wouldn't that create a negative pressure situation in and around the furnace when the blower fan is on that could recirculate carbon monoxide back into the house?
He punched the holes in your supply and return plenum boxes so so that he could do a Static pressure test I guess just for the heck of it to test the system to see what the TES P was On this new installation but when you start asking questions he knew that would only lead to more and more questions and it's a very technical subject and he probably I guess he just didn't want to go through all that but why he didn't tape up over the holes is beyond me you should at least tape up over those holes it's all you have to do and to your question no it's not going to create another service call, possibly on the supply side the whole could create condensation issue which is what this video is all about as a cold 52ﾟ air comes out in a 130ﾟ humid attic it will create condensation around that spot possibly, I don't understand why he didn't take over those holes,. He didn't puncture those holes to create another service call he did it to stick his probes into and then conduct the static pressure test until he until he realized he didn't want to do it while you were watching, And asking questions, So he didn't do it at all.
@@acadianheatingandair3291 Thank you for your reply and explanation, much appreciated. I'll seal them up! Though I must say, to not do a test just because the customer might ask a question is not a great reason to not do the test.
Hi Bryan. Love your videos. Thank you for sharing your knowledge. Do you think the Fieldpiece digital psychrometer gives a fairly accurate measurement of indoor humidity percentage and indoor dewpoint temperature?
I sprayed spray foam between the ceiling and duct box and stopped sweating and blowing air into the attic
Exactly the video I need for a sweating diffuser. Alll other diffusers in the same room are fine. One particular diffuser sweats. I'll pull the access, add additional internal sealing, reattach the diffuser, make sure no air intrusion and add additional insulation to the flex duct. By the way. It's a chilled water system, the FCU has a single speed blower. Additionally, it's a dropped ceiling in a large building so it tends to be humid above the ceiling. Humidity is regularly 85% or above. Philippines is naturally humid.
Glad it was helpful
We have condensation on the air handler and trunk in the attic in the winter when not using the a/c. The attic is ventilated, and we block and insulate the ceiling vents so the warm air does not get in the attic duct work. We have considered adding a heat coil to the unit for winter, or removing old insulation and sealing and insulating the attic with foam to make it part of our controlled environment. Can you recommend a company in North East Ohio to inspect and help with recommendations/improvements?
Hi I have mold growing around my ceiling fixtures (lights, fans) and staining around my vents, I had someone come out to check the humidity and they said it was fine.
I also have an issue with the a/c cooling one part the house and not so much the other. My house is 1500 sq ft with a 3 ton unit. What do I do?
I read recently that code now allows for houses with units within the conditioned space that have duct work in a vented attic can now have buried ducts and not have moisture issues if you follow the rules laid out like; having the leakage tested to be very low, the ducts must be rapped in R13 in the south (or R8 in the north) and then deeply buried in R19 fluffy stuff.
Holy typos Batman. Appreciate your channel bro
I have run across numerous times when a contractor installs a P- trap on secondary drain to allow condensation to flow into auxillary pan should it overflows.Mostly on electric air handlers, allowing hot air from attic & possible ambient air from auxillary drain to be siphoned into Air handler causing it to sweat heavily into auxillary pan causing it to rust.i usually add a little bit of antifreeze to seal P-trap on secondary & thus prevent sweating to occur.
My HVAC had a 6 inch duct with a blower pulling air from out side in to the main ducts. South Texas humidity is horrible year round. Vents sweating from day one of new house. Rust and mold all the time
Thanks Bryan! Wow, really really important info 😮
I’m having an issue with water intrusion/condensation pulling into my microwave, dryer and powder bath fan vent. This has turned into high moisture readings alongside the same exact wall where the dryer backs up to which is located next to the 2nd bathroom. Mold is growing along the wall behind the wallpaper in the adjoining room. Additionally, the downstairs ceiling has water stains in the shape of lines in 3 separate places. The builder is saying this is happening because of homeowner maintenance. However, I’ve been told that several of the neighboring units have had or are still experiencing microwave condensation/dripping, dryer condensation, moisture on all of the walls in the laundry room, and some other similar issues. I believe there is a flaw in the design but how would I prove this is the cause? These issues began shortly after moving in. I’ve had several companies out to assess. All humidity readings taken throughout the home have been normal. A/C unit is functioning normally. The fresh air damper isn’t defective. They ruled out a plumbing problem being the cause of the downstairs ceiling water marks. Need help to identify the problem to make the builder accountable for fixing their issue. Any advice or recommendations appreciated.
Im having this issue now in Houston, my attic is well insulated, i have sweaty vents and the house is at 70 humidity do you recommend removing the attic floor insulation, sealing the top and installing a dehumidifier
At 9:12 is it supposed to be R8 insulation? I realize codes are different everywhere, but wouldnt you always go thicker insulation in unconditioned space?
I live in an apartment in TEXAS, and too many times in the last 9 months it's been raining in my hallway from the ceiling AC unit. The main units (one for each apartment) are outside the building (I'm guessing they are the heat pump type since I get heat and AC from the same unit).The outside units aren't too old, but these apartments are 30+ yrs old, and I'm sure the inside wirings are old and outdated. I live on the ground floor of a building with 8 900+ sq foot apartments--4 upstairs, 4 downstairs.They keep "fixing" it, but it's a chronic problem. I'm sick of it--it's over 100 degrees outside, and the only way I can get it to stop raining inside is to turn off the AC. I work nights, and the constant intrusions of workmen trying to figure it out are seriously interfering with my sleep.
Great information thanks Bryan!
Hello Bryan your video is very helpful. I'm in Mimai have some issues with my attic. Anyone that you can recommend here in Miami?
How about checking the statics pressure in the supply and return
I can't believe the ridge vent was cut out. I've been in the spray foam business for 15 years and my attics rarely if never go above 83-85 F. You want a totally sealed attic and semi conditioned.
Dude come to Florida your attic is 140°. Good luck with that
If they have spray foam up top, shouldn’t the blown in have been removed? Now air can’t properly pass through from the conditioned space down below into the conditioned space of the attic.
What would you do with a damper handle that is condensating? I thought about just cover the entire damper with another section of the ductwork.
Hi,
I've found my Mate, somone clever
Thanks for all this refreshing training on humidity
I'm planning to have installed an A/C ducted in my house
The humidity come from the ground as well some walls
If you could possibly help me to choose the A/C
thanks
DomIJ
So if I have an vented attic, I live in southeast Missouri in a slab home. I have air handler inside house (conditioned space) but all duct work is in attic. It’s mostly covered with brown cellulose insulation and vents are wrapped I assume r-6. Can I close cell foam spray the ductwork?
Are you having to cut out a small hole at supply plenum to bring temp down in attic or is it the dehumidifier stand alone?
How to stop barometric bypass damper from sweating?
Question. This might sound stupid but what about raising the temperature in the attic? I remember reading in some book that sometimes raising the temperature of the space a little bit in order to remove the humidity is the best bet. Besides, you’re already burning energy by running a dehumidifier if saving energy is your goal.
Just like trying to save the planet by using electric cars instead of petro. You destroy the landfill and contaminate the earth by extracting the precious metals or you contaminate the air by burning fossil fuel. There’s no way around the it.
Think about that for a second. You are correct. However, raising the attic temperature (I.e. what used to be the default) would cure the moisture issue, and you would lose the efficiency you gained by making the enclosure better. As one great engineer says, you take 2 steps forward for efficiency, but give one back for thermodynamics and durability. But you are still better than you were.
How about taking a diffuser in the attic with low cfm from the duct in order to lower dew temperature point and balancing the temperature in the attic with room below it.
I'm in Central Florida with the air handler in the garage. There is not a chance in hell of getting humidity down to the 40-50% range. It's straight up 80-90% humidity most of the year. My ducts on the air handler are sweating bullets and it's ruining the ducts, there is water all over the floor and the bottom and corners of the ducts. What do I do? I already have some big water damage on them.
Love this informational video. I checked your website to see if you service our area as I am a Florida resident. Unfortunately you do not serve the Tampa Bay area. Is there a company you might recommend in that area? I have a sweaty plenum and honestly need the entire duct system evaluated.
Hey Bryan, I'm a Building Scientist in Florida as well. Great video! I wanna add something for anyone in the comments that has helped me.
I typically like to grab the dew point outdoors along with the attic dew point for a good comparison. Dew point in a vented attic can only, at best, be the dew point outside. If DP seems really high, but is the same as outside, at least you know the attic itself is performing well. It's a good isolation strategy. I would note that if you just use a hygrometer while on site, it's only a snapshot in time and you won't have the whole picture of what could be happening in other parts of the day. Using data loggers over a period of time are better to catch trends (putting one in the attic, in the conditioned space on each floor, one outside, etc.).
Hi Bryan
I really appreciate this video, it has been extremely helpful!!!
My attic is Icynene completely. When the 5 ton Ac was installed, they put 2- 6*8 air vents in the attic and a return ( not sure if this should have been done). The size of the attic is about 2300-2500 sq ft. My ac ducts leading into the house and the plenum boxes sweat like there is no tomorrow and the drips are causing mold growth. SO before I saw your video I just recently encapsulated them by buying over 50 cans of spray foam and spray them to create more insulation with hopefully preventing my sweating (condensation).
#1 I do not know if this will work. If you can give me some advice, please.
#2 can you highly recommend someone who knows how to deal with an attic that has been icynene and the condensation problem I am having. Someone from Miami or nearby areas that is.
I have called mountains of companies from high end to low end and they do not know what the heck I have in my attic. To them, it’s the strangest thing, and unsure if having ac vents in the attic is the ideal thing or not so they can’t give proper recommendations on how to solve my problem. I even just recently called one company and asked about the Dehumidifiers and they were not sure about adding one.
Running into your video has been a bit of a blessing because it’s exactly the problem I am having.
I would appreciate your feedback and recommendations. Thank you and stay safe. --
My attic has something similar. With sweating on the box no water in the secondary pan. But inside of my home the humidity level shows 70%. My a/c is at 70 degrees. The condensation is on the box that leads to the ducts. How can I get this fixed. I had my home built in 2014. Some bedrooms are not all that cold.
This is an area I would like to get a better handle on. Can I have a link to athe app you use in place of pychrometric chart
I just opened up my furnace and I immediately see rust and water spots inside of it.. my furnace & air handler is in an upstairs closet. When I looked in the closet the other day, I saw condensation on the refrigerant lines (I believe that's what they are? 2 copper pipes leading into where the evap coils are).. is being In a closet causing this? Or what other issue might be causing this? I started looking into this because I'm getting high humidity(nearly 70%) in house & my a/c seems to be running almost constantly.
Thank you this video I have 4 large units one unit has been sweating badly causing the alarm system to act up I'm thinking it's a fam speed due to the belt needs replaced causing fan speed to slow
Glad its helpful!
This was awesome n informative. Thank you so much for this!!
Your videos are awesome. Thanks man. Much appreciated
Good video. If i may ask a question,my new replacemnet ac is the same size as the old one. The instalation looks very maticulous,with low fan speed the evaporator coil will freeze . The ac tech, raises the fan speed to increse temp. At evaporator coil and the pressure is now 40psi instead of 30psi. The fan is so loud its unbelievable. It has a 2 speed fan motor, low speed is quiet like the old unit. He resurched the motor and foundered settings inside the motor cover, which was only marginally better. I asked if he could raise the setting on the exspansion valve so the temperate in the evap.coil would be above freezing.he said it is not adjustable and would not work well. He said the unit is too large. the old one which was installed very poorly, ripped ducks, you name it,but did not freeze and had multiple fan speeds.the home is 95 years old and only insulation in the attic foot, 6 inches. Thank you ,tim
Your refrigeration system has problem if the evaporator coil pressure is blow freezing point of 32F.
Omg I’m so lost with all the a/c verbiage!
Yea i had sweaty vents, i pull it off and you can easily see a finger nail gap on the boot. This solved my sweaty vent problem. Now i need to figure out why the light switch bracets have a water ring around it and the middle hallway of my house where the wall meets floor is sweating too. I live along the South Texas coast so yea March-Oct are the worst months of the year. Wierd how this problem literally happend after Harvey so i dont know if my house shifted or something with no damage to the outside whatsovever.
Had no idea....great knowledge!
Thanks for watching!
Awesome video thank you.. here in the Fl keys with high dew points year round.
I live in West Virginia. Crawlspaces always sweat. Don't see it as often in attics
With the infinity system in the attic and system and ductwork were sweating in dehum mode. Should the ductwork be sized for the 1st or low stage compared to maximum out put to prevent sweating?
Great job and video
Glad you enjoyed it
How do you seal, insulate and condition a air handler (in garage) that condensate? in S.W Florida
I am Having this issue in my 2 floor home. Water is inside the ducts and they tell me that I have yo change all ducts (11 vents). Ig is extremely expensive and I wonder if it is necessary?
You are either getting warm air in your ducts or It it is really humid outside your ducts in the attic causing them to sweat. Higher r-value flex may help but to me this is a symptom of high dewpoint like Bryan is saying
Is that true if you cool down inside the attic by 10 degree, that mean you would get less condensation?
I plan on building a house when I sell the one I’m in and would desperately love to end up with an AC system that actually works and doesn’t end up with the sweating ducts I have lived with my entire life here on the east coast of FL.
Put the duct inside the house exposed ! Double wall spiral ducts best and looks very good when done right !
nice,thank you for sharing your idea Sir.
You are most welcome
What is the app that you use for psychrometrics? I wasn’t able to find it on the app store.
I can't locate the app can you provide link?
I think more acoustic panels are needed at your radio station.
radio station lol... just because has has an RE20? lol i'm building acoustic panels in an hour for my amateur radio station with an RE320 :)
If you completely seal the attic by spray foaming an attic won’t it make the sheathing of the roof rot?
You dehumidify the attic properly and it won't be a problem - I also suggest using closed cell foam which will greatly reduce the issue as well
Good educational video
hmm i learned a few things, now i have some answers and solutions when i see that happen. im in south florida and seen alot lol. good vid!
Because even if you use R 8 or whatever higher R value duct in what they dont tell you is that it breaks down over time and the way they stack the insulation at supply houses it never has the R value promised ! Oh yes the ducts might be 2 inches thick but the insulation in the ac units isnt !
#sir please one video make on hvac compressor part winding cannection.
I think the most interesting thing that I heard was "radiantly Cooling"
I believe if your room temperature is set below 75 degree F, you will get "condensation," and the leaking will begin.
How can I downloaded the psycrowdegree f app
Hahaha
I thought I was coming along with hvac and the his video just tell me how much id k
Thanks for educating videos
When you conditioning a space.. say you want that space at 72. The air blowing out of the vents has to be at 52. Sweating is a product of ducts not insulated. To attics not being ventilated properly hence a fan. Soffit vents with ridge vent does NOT work unless you sustain 10-15mph winds all the time. Sealing ducts helps too! There are many many factors. Also what is the insulation value for the duct? What is a the insulation value for the run outs? There is more of a science to HVACR than average people think about.
Can someone link me to the app referred to as psycro degree f app
condensating? Don't you mean condensing?
*CHECK FOR UNHOOKED OR DAMAGED DRYER VENTS*
Point of the entire sweating issue is its in the attic ! Stop putting units and ducts in 150 degree attics ! Put them inside the envelope of the house . Spray foam should be mandatory for all homes ,trust me it works and will cut your electric bill way down ! Stop letting contractors shove units in hot attics so the can sell more square footage !
They / Contractors
Great information.
Also, the charge adjustment is important , superheat for pistons and subcooling for TXVs.
Good luck, everyone!