Aeroseal In Use on This Old House

foreign most houses like this 20 to 30 percent of the air in the ductwork never makes it to the living space because of small leaks like this so today I'm going to seal the Ducks from the inside that's next on ask This Old House [Music] Mark your house is just beautiful thank you Richard we love it here so what's up well we wrote to you guys about our heating and cooling system uh it's a forced air system all right I can see a supply register right here and that's going to blow warm air in the winter right against the glass right there that's good you should have a return here somewhere you have a return right around the corner all right so the air goes back to the furnace to be reheated right there so what's up well we put a new furnace in about 11 months ago uh we're hoping for a greater return on our investment our utility bills are much higher than we thought they had been that's not good no it's not good and you know the other big problem here is that would like to see more consistent temperatures in the house inside the house specifically upstairs okay well you're not alone a lot of people with a force warm air system complain about being uncomfortable yeah it really has been and you know another thing we noticed is that it's just very dusty there's just dust everywhere it's very annoying let's see what you got now this ductwork is insulated but it's not sealed people see this insulation say oh my ducks are sealed perfectly well I've seen it so bad that when you turn on the furnace all of a sudden the insulation blows up like that which means the air is coming right up right and it's a big deal in this country you can lose as much as 20 to 30 percent of duct losses where it doesn't actually get up to the place you want to be wow you're losing it to the attic you lose it to outside you lose it to the basement so what I actually want to do is do something new I want to show a technology where we can seal every bit of this duct work perfectly from the inside it sounds great all right Steve Taylor he's going to help us seal the Ducks today hey Steve okay Mark so how'd you get started so we've already started upstairs we've sealed all of the supply and all the return registers so now any leakage that we measure is coming just from the ductwork okay great and then you tested the ducts we did we ran a pre-test okay so we used the fan in this box okay to blow air into the duct system and see how much air is going to leak out through so that pressurized the ducts and you got tied into the computer here correct how do we do we lost 307 CFM cubic feet per minute and that's equivalent to a whole new ductwork of about 58 square inches that's a big hole wow so let's do the math 307 CFM this is a four ton system that's like just under 20 right correct okay so 20 is not coming back to be reheated you're heating your neighbor's house it's unbelievable all right so how do you seal the Ducks so in order to seal the ducts we need to do it as an aerosol so we're going to use the sealant we use the same fan that we used for the pre-test we have a nozzle that injects the liquid in to the duct the small particles that are now in aerosol travels through this flexible duct here to a y Branch gotcha then it can go to the return and the supply and we seal both at the same time you know you got heated air coming out here we want to keep that in the ductwork well on the return side it's under a negative pressure so it's pulling air in remember you complained about dust yeah well if these leak and there was any dust down here it would be sucked into the duct work and then distributed all into your house okay so all this happens from inside the docks it does we're not going to actually line all the duct work we're actually going to only seal where the breeches are the brakes and the duct work so we might see a little bit leaking out from right here in order to prove to you how it works though we're actually going to cut in a hole right here with a screen to really see it at work great so with this hole and the window screen over it I've actually simulated some of the duct leakage you have upstairs in the building so we also have to go Steve we are let her rip so we'll activate the machine okay the fan will turn on and it'll start to inject the sealant here it comes right now the Airborne sealant is flowing through the pressurized ductwork and it's squeezing out just where they have an opening in the ductwork as it's closed through those little cracks it catches on the crack and actually coagulates to seal any duct leakage now any of the ceiling that happens to leak into the living space can be captured from this scrubber fan onto the filters all right well we are done and now I can actually show you just how effective this was so instead of the hole look at this the window screen where the hole was is completely sealed and that's really the same as all the leaks in your ductwork that's cool all right so Steve what's our final numbers how do we do well if you remember we started off at 307 CFM which is equivalent to about a 58 square inch hole in the shock work yep so now we're down to 19 CF 20. great and that's only a four inch square hole well this one gets my attention right here Mark a 94 reduction in Duck leakage does that work for you yeah that's great I think your whole system is going to work better too going to be more comfortable more energy efficient and it's going to be cleaner in the ductwork great thank you for your great work Stephen thanks guys I really appreciate it oh I like the way that tightens up the system that's smart it's unbelievable it's going to be more efficient it's going to be cleaner but I think as importantly it's going to be comfortable the air that you heated or cool gets to the right place now think about the challenges with metal duct work like this every time we have a longitudinal seam right here this is not airtight it's going to leak out through here every time we bring two pieces together it wants to leak how about this these are both called takeoffs where we come off of a branch right here now these have metal tabs and you cut a hole bend the tabs well that's not going to be airtight the issue is we're losing 20 30 40 percent of the air that should be going into the living space for heating and cooling going to the wrong place wow I mean think about it well we end up putting duct workers when nobody really wants to go the basement in the Attic So that's places where when you lose it you lose it yeah so something like this is perfect for a retrofit project like you're working on here I've got a lot of them I've never seen a better solution for fixing the ductwork all right good information and a great project thank you and we've got plenty more of those coming up next time so until till then I'm Kevin O'Connor I'm Roger cook I'm Richard Dewey and I'm Tom Silva for ask This Old House you know I really like this system you have a house in mind I know I know you I know yeah [Music]