Not to be used as duct liner

Unbeknownst to me our shop was buying plenums lined with that reflective bubble wrap. Problem is that it is not approved and I talk about it here.
Link to submittal for the brand of foil insulation that was lining these plenums.
cdn.reflectixinc.com/wp-conte...

[@michaelguido7505]

Wish every company took this much care for the craft.

[@baileysair]

Thank you for your comment. I too wish that other companies would stop just switching out boxes and do load calculations on their change outs along with testing in the old system, if it is working, and then test out the new system to prove that what they installed is actually delivering and not just working. Here is another video on just that. kzbin.info/www/bejne/Y5ivaXmJbbeVqpY There are excellent classes that contractors and their employees can take, many of them free or at a reduced cost through utility companies. below is some links to those classes. NCI-Airflow Testing & Diagnostics ($) nationalcomfortinstitute.com/pro/index.cfm?pid=6705 NCI-Duct System Optimization ($) nationalcomfortinstitute.com/pro/index.cfm?pid=1779 NCI-Residential Air Balancing ($) nationalcomfortinstitute.com/pro/index.cfm?pid=3080 IHACI-System Performance Module (Free) IHACI-Air Distribution Module (Free) www.ihaci.org/education-training/class-description/ PG&E Training Great ACCA Manual J, D & S all classes are (Free) pge.docebosaas.com/learn/public/catalog/view/9 Southern California Edison Training Calendar most classes (Free) some ($) sce.ungerboeck.com/prod/emc00/EventSearch.htm?mid=1

[@JB-yq9bn]

If you look at the r value testing bubble wrap only meets 4.2 at a 20 degree delta. So in heating mode it dosent meet code anywhere in the state of California.

[@baileysair]

You are correct sir, bubble wrap does not meet California Title 24 standard of R6 and in order to get there you have to add air gaps using spacers or strips of bubble wrap. This is why we don't use it. Unfortunately, the shop was buying lined plenums for our installs that used bubble wrap for the liner. I only found out because of an install where I was testing the system in the attic and saw moisture dripping off the plenum. When I laid my hand on the plenum it was ice cold. I asked Robert our installer if the plenum was lined and he said yes, with bubble wrap. I had him wrap the plenum with 2" FSK and that stopped the moisture. I contacted the manufacturer and the supply house we purchased the plenums through. They both didn't know this was a problem. In fact, the manufacturer sent me the submittal sheet for the product they were using to line the plenum, and on the submittal sheet it plainly stated that the product can not be used as a liner. I asked them if they actually read the literature they were using for a submittal, all I heard was crickets! In the same light we don't use duct board, we only use metal plenums, with a caveat, we do use it to line return chambers. Over the years I have seen poorly manufactured duct board plenums falling apart in attics. With sheet metal plenums this does not happen. Thanks for the comments.

[@johnsonbar5022]

I have a wood burning stove that has a ductwork that feeds heat to a room on the first floor. My wood burning stove is in the cellar and the ductwork that comes off of that goes along the celling of the cellar and connects to a floor vent in a room on the first floor of our house. We are putting in a ceiling in the cellar and I don't want the ductwork that gets hot off the wood stove to discolor the wooden ceiling panel that will be directly under the ductwork off the wood burning stove. Can you suggest a safe ductwork wrap that will lessen the heat that the wood paneling will be exposed to, to lessen the possibility of that wood paneling being discolored by heat.

[@baileysair]

So a 6" air gap between the duct and any combustible material would be best. You could use Rockwool as it is fire resistant and should do the trick or use 3M fire barrier duct wrap. Here is the link www.3m.com/3M/en_US/p/d/v000159076/

[@CG-qc1ob]

Thanks for your video . What insulation can I use inside the heater exchange box ?

[@baileysair]

You would need to contact the manufacturer of the equipment to see what they would approve. Inside plenums use standard duct liner.

[@FracturedReality777]

The reflectix may not work as a liner but it works great on the garage door to reduce the amount of heat in the garage.

[@baileysair]

Yes it has the reflective coating and that will work wonders.

[@JohnHarrisCountryBoyCooking]

I noticed the box on top of my air handler was wet and the closet that it sits in was cold so I started to look and sure enough cold air was flowing out all around the unit. Can I wrap the metal box on top with something I also sealed all the leaks. Will that help cool off faster

[@baileysair]

Sealing air leaks will definitely help. And yes you can wrap it with preferably fiberglass insulation. You could use the bubble wrap as long as there is an airgap. See installation instructions link below , kzbin.info?event=video_description&redir_token=QUFFLUhqblpWWHZKSlhtd2V6NXg4N2VMM3h0cFBGbDYyZ3xBQ3Jtc0ttRkxFQnhaZHZQZzVDamlfejBJQy1FOW9RNW9ZTHRsODgtRHd5UVpRaXRmbUJzZzhITE15aTgxNGdOekl6TkNZXzRjWEVKM1hjeG5nOV94OC1IS2cteWxZNjdhOHk0R3g4NTI2clVzVjIycE9YX1VKOA&q=https%3A%2F%2Fcdn.reflectixinc.com%2Fwp-content%2Fuploads%2F2021%2F12%2FN16-%25E2%2580%2593-R-4.2-Duct-Insul-Submittal-Revised-012021.pdf&v=5wcFXGEr_YM

[@davedakroub5323]

I live on a crawl space, my main trunk pops/bangs in cold weather with the heat on. I put a few braces on with the thought it may stiffen & reduce any flexing making it quiet down, but it did not help. I believe it needs to be insulated, if nothing else my energy costs should go down. Does insulating usually resolve that type of issue, if so what type of insulation would you recommend? The space does get humid. Probably not in the budget to hire a company at the moment so I’m going to attempt it myself. My Dad did HVAC but unfortunately passed and any friends of his still alive that were in the HVAC field are elderly 😩 Thank you in advance.

[@baileysair]

Sounds like you have square duct. The problem with metal square duct is it will expand and contract when heated and cooled. Also, when the system comes on it will pressurize in the supply and depressurize in the return, this can cause oil canning where the metal will pop. If the ducts were constructed correctly and cross broke they will not usually pop or bang. If it is a heating issue then the metal is expanding and contracting which will be a little more difficult to get rid of. I have screwed L brackets to the metal and this sometimes stops it. Insulating wouldn't hurt either but that can be very labor intensive in a crawlspace and may not fix the issue. If it is an expansion contraction problem you could put in some expansion joints made with flex connector and this might get rid of it. Link below to flex connector and a video. ductanddampers.com/catalog/Duct-System-Components/Fabric-Duct-Connector/Flexible-Duct-Connector-SKU2172 kzbin.info/www/bejne/g4Wbpn-vl66indE kzbin.info/www/bejne/m3u8k2WNe6l2d6s

[@davedakroub5323]

@@baileysair Thank you for your help! They are square duct. I think the sheet metal they used was too thin or just not designed correctly. I will try adding more bracing to stiffen it, I didn’t do a thorough job the first time as I wasn’t sure it would help. It was suggested maybe a blower fan speed adjustment would help, something along the lines of the return might be starved of air, but guessing it wouldn’t help because the old furnace did as well as the new, no change. It pops after the blower is off for 5-10 minutes depending on the outdoor temperature, no issues when running the ac. Craw is about 4 feet tall, so not to bad at all. Thank you again!

[@baileysair]

Be careful with blower adjustments as a slower speed will increase the air temperature and if lowered too much will push it past design of the unit. Furnaces have a min and max temp rise. You want to stay in the middle of that. This will be stamped on the furnace data plate. For example, if it said temp rise 40-70 means that the air coming out of the register compared to going in the return should be between those numbers. So if the air is 60 degrees coming in then you don't want it higher than 130 or lower than 100 preferably right in the middle at 55 which would be 115 degrees. NCI has another system based on the equipment efficiency. If the equipment is 90% efficient they use 150 cfm per 10,000 BTU's so a 80,000 btu furnace that is 90% would require 8X150 for 1200 cfm, for 80% its 130 cfm per 10,000 so same size would take 8X130 = 1040 cfm, and for a 70% needs 100 cfm per 10,000 same size 8X100=800 cfm. These settings will give you the highest efficiency for the furnace. So, it would be better to check the temp rise and or set the airflow. There are several videos on how to take a static pressure and then determine the fan speed and the amount of cfm the furnace is moving. But most techs just take the temp rise and set it at the magic middle as shown above. You would be much better doing a fix to the ducts and then set your temperature rise. @@davedakroub5323

[@renemartinez9495]

Questions My insulation from inside of he furnace got deglued what would you recommend to put back inside it or outside

[@baileysair]

Best way on a furnace is to put it on the inside and attach it with some sheet metal so it wont come off.

[@Vleegz]

what are your thoughts on using a poly iso for the air return? i think im heating my air a ton on the air return side of the air handler. thanks!

[@baileysair]

I am not sure that Polyiso is rated to be used as duct work as it can emit hydrogen cyanide when it burns. This is very toxic. I believe it is okay to wrap a metal plenum with it as they use it to insulate roof decks all the time. However, I would not put in the airstream. I know it has a great R-value per inch, is very durable, but you could layer duct board and get similar results for probably the same cost and no hazard if it catches fire.

[@Vleegz]

@@baileysair good to know. I plan to do it on the outside.

[@megevans2887]

What is FSK? Have any suggestions for fiberglass free insulation on outside of plenums (sp?)? Thanks

[@baileysair]

FSK stands for Foil Scrim Kraft faced insulation. If you want a non fiberglass wrap, then use the bubble wrap or Astro-Foil but follow the manufacturers instructions on how to install it as it needs an airgap in order to have any real R-value.

[@jcnol1]

The insulation in my plenum is falling apart. If I want to replace, what material can be used? It is currently attached to sheet metal.

[@baileysair]

There are a wide range of duct liners available, below is a link to Johns Manville page on duct liners. You would want to attach the liner using spray adhesive below is a link for DuroDyne adhesive page. I would also use dyna stick self adhesive pins to help hold the liner. The alternative is to wrap the duct work using FSK insulation. Here is a link on us applying it to some ductwork in a garage, by the way, you don't glue it on you staple it or pin it and then tape the vapor barrrier. Insulating KD Pipe in a garage: kzbin.info/www/bejne/fJaaeaSqbdqGoZI Johns Manville Duct Liners www.jm.com/en/hvac/duct-liner/ DuroDyne Adhesives: durodyne.com/AdhInsAhes.php Dynastick self adhesive pins; durodyne.com/InsFasMech.php

[@monkrph]

Which one do u choose ?

[@user-iw8fh1hu1l]

What kind of insulation for the metal duct on the outside please and thank you

[@baileysair]

We like to use FSK insulation, 3" FSK provides R8 of insulation. Here is a link to more about exterior duct insulation. www.jm.com/en/hvac/external-duct-insulation/

[@GregoryGuay]

I want to make a coffin shaped box/ plenum to reduce sound escaping my home music room/band rehearsal room. I've heard the best way to go is a labyrinth of duct insulation inside. Do you/anyone have experience or suggestion for the best product for this? Located in southern US.

[@baileysair]

We have made baffle boxes that go under the furnace in the return to deaden the sound. These boxes were made of metal and lined with duct liner. Basically they were designed to not allow sound a strait path through the box when combined with the duct liner to absorb the sound. These baffle boxes would reduce the sound by about half, and make a loud furnace much quieter. This is why sound rooms use those foam tiles with pyramids on them to not reflect the sound and instead absorb the sound. Trane manufacturing has some software they use to design out loud equipment and system noises, it's called TAP. I am not sure if you can get a copy of the software but it can help design spaces to minimize noise. Here is a link to the manual software.trane.com/RightNow/0917-InstallationGuides/TraneAcousticsProgramGettingStarted.pdf and here is another slide presentation on sound www.trane.com/content/dam/Trane/Commercial/global/products-systems/education-training/continuing-education-gbci-aia-pdh/Evaluating-Sound-Data/APP-CMC055-EN_course_material.pdf Just realize that sound will bounce of hard surfaces and be absorbed by soft surfaces like duct liner or duct board. If you angle the board or liner will also trap sounds so they don't travel. Good luck.

[@GregoryGuay]

@@baileysair I'm thinking about sending my 8" duct into a zig zag labyrinth / baffle box and then coming out to the vent.....

[@baileysair]

@@GregoryGuay Is the duct metal or flex? If it is metal you can build a duct board box and run it through that and add a few feet of flex, it will reduce the sound but it will also reduce the airflow. Longer flex less noise.

[@andrewmckinlay2964]

I don’t get it. If astrofoil has an appropriate r-value, then how is the sheet metal getting cold?

[@baileysair]

So the instructions require a spacer for the foil bubble wrap to give the at least R4 if glued directly to the metal it isn't providing enough insulation to keep it from sweating. Sweating ducts are more common in humid climates like Florida. That is why they put a vapor jacket/barrier on flex duct to help keep them from sweating. The problem with the foil bubble wrap in our situation was metal was hitting the dew point and condensing moisture out of the air in the attic, much like a glass full of ice water will sweat. One wrap of FSK solved the problem, and we use R8. This is on the supply side, on the return side there would be no sweating.