Thanks for making such a detailed video. We just converted our garage into living space, and this video is exactly what we needed to add ducts and boots to the new space
Appreciate the detailed video. Saved me some cash of paying to have this done. My kids thank you as well now their room won’t be hotter than the rest of the house.
Can you show the whole system from the main Plenum?? question is…are you using the flex duct for the whole system? I was researching and I read that you’re not supposed to use flex duct longer than 5 to 7 feet. I’m in Florida and it looks like in the attic they use it on everything … just curious what’s correct. thank you.
One more quick tip if you use duct sealer on the inside of the takeoff you will seal in all of that fiberglass ps I do systems with 3% air loss I only tape the flex to the takeoff and put a zip tie putting the sealer on the inside first is going to be extremely messy especially for somebody that is not skilled in this trade just food for thought by aluminum tape works fine I've done hundreds of homes and pass with 3% air loss which is what they want in an energy star home
Ph1s/Ph2s and adjustable elbows with blocking or snipping tabs out of Boot tend to be make for much better air flow and distribution out of register and make securing the register better too. However those B-box do make it a whole lot quicker and easier 👍🏽
Great video, not in the trade but love learn new stuff. I am still waiting to find out when do you need to use spray the foam. 😂 Also, I have the “M” around one vent in the closet. Any tip how to insulate to prevent moisture? I got in the attic in the past but could find any roof leak so pretty sure it is condensation despite everything looks sealed.
You can apply small amounts of spray foam to cover the metal boot in unconditioned space to prevent moisture and mold that can occur in extreme temperatures. Use the type that expands minimally. I love using this one...... amzn.to/3wD5gCB
This might vary by state, but when, mounting this way on the ceiling from the attic, are you required by code to use metal boot rails to fasten it to the studs?
Great video, much thanks! However my register screws hit the sheet metal on the register. Did you drill pilot holes into the sheet metal? Or am I supposed to wooden frame the register so the register screws have somewhere to bite other then drywall? This is a ceiling register 10x10 and don't want it to fall.
The sheet metal has a "series" of tiny pilot holes to help securing the register to the ceiling, via securing the register to the metal of the boot assembly.
None of the box stores sell vent duct boxes like that with the screwing flange. All of the ones they sale are just the box itself with new mounting brackets (the pieces on the end with the screw holes)
Nicely done- hey I like that double stick tape idea and you mentioned that you would post a link to brand and where to buy but I don't see that here...Can you provide info?
If the duct is sealed properly, no fiberglass from the attic should enter the living area, When cutting fiberglass rigid duct board, you can simply use a shop fav near while another person cuts it, to avoid spreading the fibers.
To reduce resistance, it would be better to use a rigid tapered 90 degree or similar connector between the register and the flex duct (24:30). Also a tapered connection off the plenum. Otherwise, great video and camera work!
Thanks for the comments! In the past, we actually used the collars, but find them to be extremely leaky and hard to insulate, thus causing condensation, and eventually mold with the extreme temperature differences between the conditioned air, and the extreme unconditioned space. But if the attic has spray foam, for example, we use the type that can be maneuvered, like this one..... amzn.to/49UIjZO
@@SaveGreenHere Hi there. Actually I was referring to a non-adjustable collar which has much less leakage. You can also fabricate them out of semi-rigid flex duct pretty easily and they don't have to be long, just enough to have the bend be well supported and protect it from crimping. You can see what I mean in Manual D group 8 "elbows and offsets". Its the smooth rounded elbow and the equivalent length is very low. You can pull the flex duct over them to the register so insulation shouldn't be too much of a problem.
This is the one we use for flex systems........ amzn.to/4ciqOEA and for metal........ amzn.to/4eIKao0 use the holes to hang onto rafters or drill onto metal beams on steel buildings.
Check out these videos, as there are many variables when sizing........ ruclips.net/video/s6qpuo9EwXo/видео.html and studio.ruclips.net/user/video1r3zUzhnqk0/edit
Can you use duct work aluminum tape to seal around the edges of the sheet rock where the registers meet the sheet rock to keep any attic air from leaking into the conditioned space?
Tape does not provide an airtight seal, so the answer is NO. The adhesive on the tape also comes loose in extreme heat, extreme cold, which is what you see in unconditioned spaces. Best you use this............ amzn.to/3TCgW1r
Thanks, I used mastic and tape in the unconditioned space on duct work connections something the installers failed to do. I meant in the living space the register vent that goes on the wall or ceiling I’ve seen installers applying the foil tape there were the vent meets the sheet rock before installing the vent faceplate.
Not sure why but my response has been deleted multiple times so I will try to post it as a new comment: Hi there. Actually I was referring to a non-adjustable collar which has much less leakage. You can even fabricate them out of semi-rigid flex duct pretty easily and they don't have to be long, just enough to have the bend be well supported and protect it from crimping. You can see what I mean in Manual D group 8 "elbows and offsets". Its the smooth rounded elbow and the equivalent length is very low. You can pull the flex duct over them to the register so insulation shouldn't be too much of a problem.
I have high static pressure on a new 3.5 ton heat pump. I know for sure the flex duct is the issue. I have two 12" coming out of the supply in opposite directions. I know I need an 18" for a 3.5 ton heat pump. I did a diagram layout of the duct in the attic. What would happen if I just replace the two 12" to 18"? Ignoring the downstairs, because everything is between the walls. The problem was even worse with an undersized return. The original and only return was a 24x18. The total static pressure on the unit was .9 W.C. I was able to drop the TESP to .66 by making the return 30x24. Since there is so much static pressure and the unit TESP is a .2 and I need an 18" for a 3.5 ton for 1400 CFM. How big does the supply plenum should be and what shape? Should the supply plenum split to 3 18" going out to each of the 3 distribution boxes? Do the other three distribution boxes also need to be larger? Looking at the triangle shaped supply plenum I have very little room up for a rectangle plenum. I think a 3 feet ductboard supply plenum should work. There is a foot from the Air handler to the ceiling and I think 2 feet from the attic floor to the roof. Now I am looking at two types of designs. Design #1 keeps the 18" ducts straight by having a single 18" coming out of the supply and then a distribution box splitting it to three 18". The sides would be coming out straight to the to side boxes and one going to the third box with a slight curve. Design #2 splits to three right at the supply plenum and goes to each box individually, but all three will have a slight curve. I will not be using any metal plenums..... it will be all flex duct and ductboard boxes, because of budget. I am not trying to make a perfect system, but trying to remove the restriction from the 12" undersized ducts installed and replacing the flex duct that was patched with mastic with new ones. Another question about the installation..... I have the flex duct running up and strapped to the roof for support. Since the supply plenum is low to the floor due to the roof..... Can the flex duct be run on the attic floor? Can you tell me which layout makes more sense and less restrictive? Thank you. Layouts: Current i.ibb.co/Ld9kmPM/Flex-Duct-Layout-and-Size.jpg Option #1 i.ibb.co/GHyS00g/2022-07-05-0002.jpg Option #2 i.ibb.co/PNN8mSB/2022-07-05-0001.jpg Air Handler Specs ibb.co/17VvF4B Video of attic ruclips.net/video/iInIN89q8GU/видео.html
Almost seems like two 18" flexes will affect static, but the other way around, as they will be waaaay too big. Return seems fine after your increase. However, make sure the actual return chase is wide enough, not just the grill or wall opening. You may want to check the condition of the coil. A dirty, or obstructed coil, WILL affect your static. Pertaining to the question on changing the boxes, and other ducts, yes, if those are not changed, your static will still be off. So the boxes, and the ducts coming off the boxes need to be upsized, accordingly, to accommodate the increased CFM coming into them as well. I did a simple video for customers, years ago, and that may help...... ruclips.net/video/wyDAO461h68/видео.html
@@SaveGreenHere what do you mean by two 18" flexes will affect static? In a positive or negative way? Right now is undersized. I have a 3.5 air handler with 1,400 CFM and it's going out the supply to two 12" flexes. For a 3.5 ton heat pump it requires 18", which would reduce static pressure. The return is completely open inside. I can go in it and clean the coils from underneath. It's not the grill or wall widen, but the whole area underneath. The units is not a year old and coils are clean. The static pressure at the return is just 1.5 WC with the filter. Its also a 3" depth filter which is less restrictive. The static pressure at the supply is .50. originally with the old undersized return the TESP was .9 WC.... It was almost 1. I was hoping to try keeping the other extension the same size and just put in a bigger supply trunk plenum, replace the 12" to 18" and send 3 18" to each distribution box. I didn't know which of the layouts is best or if you had other suggestions. I am not trying to get a perfect balance system. I was hoping to just reduce the static pressure drastically like I did with the return. Remove the pressure from the blower motor.
I would personally use a ductulator like the ones shown on the video I referenced....... amzn.to/3yiBK2d Or an online one like this one.... www.oceanhvac.com/ductulator/ But from my experience, two 18" round flex ducts will easily both be topping over 2300 CFM. Too big for a 3.5 ton air handler. Check the speed of your blower as well.
I have this in my home (the fabric stuff) and there is white stuff on it, almost like spray paint... is paint something y'all use on the inside or is it the "M" word??
I know this is going to sound crazy but i want to do this for my garage. I live in south texas and air flow sucks in my 2 car garage and i would love to do some work in it. Do you think its worth adding a duct to my garage and if so, what size?
Well, if you supply air to any room, you also need a return. Not having a return is like running your unit with a window open. The air will simply not return to the unit to be re-conditioned. That being said, doing this in a garage is actually a DANGER because of possible carbon manoxide, and fumes such as paints, gasoline, and others. Your best solution is to install one of these for under $400..... amzn.to/3KSguY1 Search my youtube, as we have various videos on them.
I hope you are talking about a system dedicated to the garage. that is a major violation to install ductwork into a garage from the system feeding the house. Very dangerous because of carbon monoxide from vehicles.
I know he said it would be utilized but I’m thinking that was a mistake he left a note text on the video to correct it instead of refilming. It said “it’s optional if coming in from the floor to seal gaps. Not practical for ceilings though”.
I cringed while watching this. I had an entire new system installed in my home and I know they didn't do 1/2 the things you did. I get all sorts of smells from the attic in the home. Excessive dust...It's a nightmare....
Unfortunately most "new construction" duct installs are done wrong, including wrong smaller sizes, as they are cheaper. The results is an undersized duct system. So you may have a 4 ton HVAC system with 3 tons of ducts, as far as sizes go. This video goes over duct sizing....... ruclips.net/video/wyDAO461h68/видео.html
Here's a valuable tip: The new metal duct is so thin that dropping an 8" elbow to the floor will destroy it, don't ask me how I found out. Today's duct is NOT your father's. Maybe two is better.
I know this is two years old but after watching a bunch of videos, this was the only one that was actually helpful. Thank you!
Great to hear!
Probably the best video on how to do this that I have seen yet
Thanks!
Thanks for making such a detailed video.
We just converted our garage into living space, and this video is exactly what we needed to add ducts and boots to the new space
Glad it was helpful!
Appreciate the detailed video. Saved me some cash of paying to have this done. My kids thank you as well now their room won’t be hotter than the rest of the house.
Glad it helped!
Wow! Congratulations, everything taught in great detail in the most efficient manner. Thank you Maestro and God Bless
So nice of you!
What an amazingly detailed video with top notch advice! Thanks for taking the time to share!!
Such a great video, very well explained. I’m new into HVAC and haven’t learned much about ducts, and this was very informing
Glad it was helpful!
You are a Great instructor (step-by-step) teaching all the steps to do the task. Thank You
Glad it was helpful! Thanks for subscribing!
This type of work should be taught in trade schools amazing video
Appreciate the love! Feel free to share!
Can you show the whole system from the main Plenum?? question is…are you using the flex duct for the whole system? I was researching and I read that you’re not supposed to use flex duct longer than 5 to 7 feet. I’m in Florida and it looks like in the attic they use it on everything … just curious what’s correct. thank you.
This is the greatest video of all time! Great filming, fantastic execution, cool dude.
Wow, thanks! Please support and SUBSCRIBE!
One more quick tip if you use duct sealer on the inside of the takeoff you will seal in all of that fiberglass ps I do systems with 3% air loss I only tape the flex to the takeoff and put a zip tie putting the sealer on the inside first is going to be extremely messy especially for somebody that is not skilled in this trade just food for thought by aluminum tape works fine I've done hundreds of homes and pass with 3% air loss which is what they want in an energy star home
Great! Thanks!
Wish I could’ve seen you tape down the outer layer. Love the video. Thank you so much.
Next time! Thanks for the support!
Ph1s/Ph2s and adjustable elbows with blocking or snipping tabs out of Boot tend to be make for much better air flow and distribution out of register and make securing the register better too. However those B-box do make it a whole lot quicker and easier 👍🏽
Thanks!
Great video, not in the trade but love learn new stuff. I am still waiting to find out when do you need to use spray the foam. 😂 Also, I have the “M” around one vent in the closet. Any tip how to insulate to prevent moisture? I got in the attic in the past but could find any roof leak so pretty sure it is condensation despite everything looks sealed.
You can apply small amounts of spray foam to cover the metal boot in unconditioned space to prevent moisture and mold that can occur in extreme temperatures. Use the type that expands minimally. I love using this one...... amzn.to/3wD5gCB
This might vary by state, but when, mounting this way on the ceiling from the attic, are you required by code to use metal boot rails to fasten it to the studs?
Only in new construction. Retrofit application is different, as drywall is already laid out.
Excellent how to.
Thanks helped a lot.
Much appreciated!
Great video, much thanks! However my register screws hit the sheet metal on the register. Did you drill pilot holes into the sheet metal? Or am I supposed to wooden frame the register so the register screws have somewhere to bite other then drywall? This is a ceiling register 10x10 and don't want it to fall.
The sheet metal has a "series" of tiny pilot holes to help securing the register to the ceiling, via securing the register to the metal of the boot assembly.
None of the box stores sell vent duct boxes like that with the screwing flange. All of the ones they sale are just the box itself with new mounting brackets (the pieces on the end with the screw holes)
Get it here..... amzn.to/4e4d6oV
Nicely done- hey I like that double stick tape idea and you mentioned that you would post a link to brand and where to buy but I don't see that here...Can you provide info?
Yes...... amzn.to/3H72rwH
The exposed fiberglass fibers won’t go airborne into the rooms?
If the duct is sealed properly, no fiberglass from the attic should enter the living area, When cutting fiberglass rigid duct board, you can simply use a shop fav near while another person cuts it, to avoid spreading the fibers.
@@SaveGreenHere what about the fiberglass in that drop register
As mentioned, simply use a shop vac near while another person cuts it, to avoid spreading the fibers.
Also. Couldn't you put seal around box lip where lip side meets ceiling floor as well? Before screwing box down.
Yes u can
At 16:34 into the video, You didn't say what the white sealant is , is it Mastic or the regular sealant/caulk?
amzn.to/3rhTJ3l
To reduce resistance, it would be better to use a rigid tapered 90 degree or similar connector between the register and the flex duct (24:30). Also a tapered connection off the plenum. Otherwise, great video and camera work!
Thanks for the comments! In the past, we actually used the collars, but find them to be extremely leaky and hard to insulate, thus causing condensation, and eventually mold with the extreme temperature differences between the conditioned air, and the extreme unconditioned space. But if the attic has spray foam, for example, we use the type that can be maneuvered, like this one..... amzn.to/49UIjZO
@@SaveGreenHere Hi there. Actually I was referring to a non-adjustable collar which has much less leakage. You can also fabricate them out of semi-rigid flex duct pretty easily and they don't have to be long, just enough to have the bend be well supported and protect it from crimping. You can see what I mean in Manual D group 8 "elbows and offsets". Its the smooth rounded elbow and the equivalent length is very low. You can pull the flex duct over them to the register so insulation shouldn't be too much of a problem.
Just use a strap to hang the flex duct on the truss.
This is the one we use for flex systems........ amzn.to/4ciqOEA and for metal........ amzn.to/4eIKao0 use the holes to hang onto rafters or drill onto metal beams on steel buildings.
Bros a unit grabbing that fiber glass bare handed!
Just don't touch your face after ha ha.
What is the ideal duct size? I need to replace it in my home and are going to use the flex duct but dont know if 6 or 8 inch give enough air flow.
Check out these videos, as there are many variables when sizing........ ruclips.net/video/s6qpuo9EwXo/видео.html and studio.ruclips.net/user/video1r3zUzhnqk0/edit
Just what I was looking for. Thanks, be blessed always
You're welcome 😊
I would say dont slide.duct.on too far. Just maybe finger width also spray glue for the tape.
👍
Great video! Thank you
Glad you liked it!
@ 16:31 what is the weather stripping used for the register box?
Just an added layer to create an airtight seal.
The duct adhesive in the amazon link is acrylic yet you said you prefer water based.
I checked again and it's water based, red devil.
Fantastic video!👍
Thank you very much! Please subscribe and share!
Can you use duct work aluminum tape to seal around the edges of the sheet rock where the registers meet the sheet rock to keep any attic air from leaking into the conditioned space?
Tape does not provide an airtight seal, so the answer is NO. The adhesive on the tape also comes loose in extreme heat, extreme cold, which is what you see in unconditioned spaces. Best you use this............ amzn.to/3TCgW1r
Thanks, I used mastic and tape in the unconditioned space on duct work connections something the installers failed to do. I meant in the living space the register vent that goes on the wall or ceiling I’ve seen installers applying the foil tape there were the vent meets the sheet rock before installing the vent faceplate.
expanding spray foam would be a far better idea.
Would I be able to do that same process on a ceiling tile?
Depends how strong your grid is installed.
Not sure why but my response has been deleted multiple times so I will try to post it as a new comment:
Hi there. Actually I was referring to a non-adjustable collar which has much less leakage. You can even fabricate them out of semi-rigid flex duct pretty easily and they don't have to be long, just enough to have the bend be well supported and protect it from crimping. You can see what I mean in Manual D group 8 "elbows and offsets". Its the smooth rounded elbow and the equivalent length is very low. You can pull the flex duct over them to the register so insulation shouldn't be too much of a problem.
Thank you.
@@SaveGreenHere Looks like my comment reappeared below after a couple of days. Maybe a youtube glitch. Anyway, thanks for the videos!
Excellent, just what I needed, thank you and God Bless
Glad it was helpful!
Best video ever ..great job
Thank you so much 😀
Great video. Thank you.
Thank you!
I have high static pressure on a new 3.5 ton heat pump. I know for sure the flex duct is the issue. I have two 12" coming out of the supply in opposite directions. I know I need an 18" for a 3.5 ton heat pump. I did a diagram layout of the duct in the attic. What would happen if I just replace the two 12" to 18"?
Ignoring the downstairs, because everything is between the walls. The problem was even worse with an undersized return. The original and only return was a 24x18. The total static pressure on the unit was .9 W.C. I was able to drop the TESP to .66 by making the return 30x24. Since there is so much static pressure and the unit TESP is a .2 and I need an 18" for a 3.5 ton for 1400 CFM. How big does the supply plenum should be and what shape? Should the supply plenum split to 3 18" going out to each of the 3 distribution boxes? Do the other three distribution boxes also need to be larger?
Looking at the triangle shaped supply plenum I have very little room up for a rectangle plenum. I think a 3 feet ductboard supply plenum should work. There is a foot from the Air handler to the ceiling and I think 2 feet from the attic floor to the roof. Now I am looking at two types of designs. Design #1 keeps the 18" ducts straight by having a single 18" coming out of the supply and then a distribution box splitting it to three 18". The sides would be coming out straight to the to side boxes and one going to the third box with a slight curve. Design #2 splits to three right at the supply plenum and goes to each box individually, but all three will have a slight curve. I will not be using any metal plenums..... it will be all flex duct and ductboard boxes, because of budget. I am not trying to make a perfect system, but trying to remove the restriction from the 12" undersized ducts installed and replacing the flex duct that was patched with mastic with new ones.
Another question about the installation..... I have the flex duct running up and strapped to the roof for support. Since the supply plenum is low to the floor due to the roof..... Can the flex duct be run on the attic floor? Can you tell me which layout makes more sense and less restrictive? Thank you.
Layouts:
Current
i.ibb.co/Ld9kmPM/Flex-Duct-Layout-and-Size.jpg
Option #1
i.ibb.co/GHyS00g/2022-07-05-0002.jpg
Option #2
i.ibb.co/PNN8mSB/2022-07-05-0001.jpg
Air Handler Specs
ibb.co/17VvF4B
Video of attic
ruclips.net/video/iInIN89q8GU/видео.html
Almost seems like two 18" flexes will affect static, but the other way around, as they will be waaaay too big. Return seems fine after your increase. However, make sure the actual return chase is wide enough, not just the grill or wall opening. You may want to check the condition of the coil. A dirty, or obstructed coil, WILL affect your static. Pertaining to the question on changing the boxes, and other ducts, yes, if those are not changed, your static will still be off. So the boxes, and the ducts coming off the boxes need to be upsized, accordingly, to accommodate the increased CFM coming into them as well. I did a simple video for customers, years ago, and that may help...... ruclips.net/video/wyDAO461h68/видео.html
@@SaveGreenHere what do you mean by two 18" flexes will affect static? In a positive or negative way? Right now is undersized. I have a 3.5 air handler with 1,400 CFM and it's going out the supply to two 12" flexes. For a 3.5 ton heat pump it requires 18", which would reduce static pressure. The return is completely open inside. I can go in it and clean the coils from underneath. It's not the grill or wall widen, but the whole area underneath. The units is not a year old and coils are clean. The static pressure at the return is just 1.5 WC with the filter. Its also a 3" depth filter which is less restrictive. The static pressure at the supply is .50. originally with the old undersized return the TESP was .9 WC.... It was almost 1. I was hoping to try keeping the other extension the same size and just put in a bigger supply trunk plenum, replace the 12" to 18" and send 3 18" to each distribution box. I didn't know which of the layouts is best or if you had other suggestions.
I am not trying to get a perfect balance system. I was hoping to just reduce the static pressure drastically like I did with the return. Remove the pressure from the blower motor.
I would personally use a ductulator like the ones shown on the video I referenced....... amzn.to/3yiBK2d Or an online one like this one.... www.oceanhvac.com/ductulator/ But from my experience, two 18" round flex ducts will easily both be topping over 2300 CFM. Too big for a 3.5 ton air handler. Check the speed of your blower as well.
I am buying my stuff from your referral link. Good stuff
I appreciate that. Thanks again!
I have this in my home (the fabric stuff) and there is white stuff on it, almost like spray paint... is paint something y'all use on the inside or is it the "M" word??
Spray paint is usually not used in Duct applications.
Could be mastic. It helps to seal
Good stuff
Appreciate it
I know this is going to sound crazy but i want to do this for my garage. I live in south texas and air flow sucks in my 2 car garage and i would love to do some work in it. Do you think its worth adding a duct to my garage and if so, what size?
Well, if you supply air to any room, you also need a return. Not having a return is like running your unit with a window open. The air will simply not return to the unit to be re-conditioned. That being said, doing this in a garage is actually a DANGER because of possible carbon manoxide, and fumes such as paints, gasoline, and others. Your best solution is to install one of these for under $400..... amzn.to/3KSguY1 Search my youtube, as we have various videos on them.
I hope you are talking about a system dedicated to the garage. that is a major violation to install ductwork into a garage from the system feeding the house.
Very dangerous because of carbon monoxide from vehicles.
Is it possible to put in a window a/c unit? If so, that is probably your best bet.
Actually, a mini split is better. amzn.to/4fKp34D
Stupid question, what does the grill screw into?
The metal can unit in the attic, through the drywall.
Sir you have vacancy I am hvac air conditioner duct fitter 15 years experience Gulf country in Kuwait
Did I miss where the spray foam went??
I know he said it would be utilized but I’m thinking that was a mistake he left a note text on the video to correct it instead of refilming. It said “it’s optional if coming in from the floor to seal gaps. Not practical for ceilings though”.
Really helpful. Thank you
Glad it was helpful!
Thanks!
Thank you!
2" ! When it counts!
Hi, how can we contact you for business inquiry?
We don't do business online, sorry.
We do not conduct business online. Sorry.
Thanks for your reply. You're so nice!
I cringed while watching this. I had an entire new system installed in my home and I know they didn't do 1/2 the things you did. I get all sorts of smells from the attic in the home. Excessive dust...It's a nightmare....
Unfortunately most "new construction" duct installs are done wrong, including wrong smaller sizes, as they are cheaper. The results is an undersized duct system. So you may have a 4 ton HVAC system with 3 tons of ducts, as far as sizes go. This video goes over duct sizing....... ruclips.net/video/wyDAO461h68/видео.html
Much appreciated. I'm going to have the system all taken out and completely re-done. I just need to find the right contractor. @@SaveGreenHere
New 470a refrigerant that replaces 410a refrigerant, with Do-It-Yourself kit included..... ebay.us/tVSqEv
Here's a valuable tip: The new metal duct is so thin that dropping an 8" elbow to the floor will destroy it, don't ask me how I found out.
Today's duct is NOT your father's.
Maybe two is better.
There are thicker mil out there, but of course, cost more.
SaveGreenHere, do you know a good site to learn to calculate the sizes of the flexduct?
Here's a video on duct calculating duct sizes. ruclips.net/video/1r3zUzhnqk0/видео.html You will need to purchase this kit.... amzn.to/4eMja71