Taping furnace air ducts - Page 2

Daox · 03-07-10, 08:35 AM

Well, that last bit of duct sealing really did something. I'm not exactly sure why (feel free to comment), but the air coming out of the ducting is now coming out at a much higher velocity than before. I hadn't noticed this on any of the other taping sessions yet, but this is quite drastic. I imagine that is a good thing?

ksstathead · 03-07-10, 03:43 PM

Our 1948-vintage home was retrofitted with central heat & air decades ago, using the uninsulated exterior wall cavities for return air. Likely a code violation even when done, I don't know. Of course, at a later point, someone blew in insulation into the walls. Two great things do not always make a peanut butter cup.

We bought it in '98, and the HVAC kicking on would SLAM the basement door closed, as the stairway had become the primary return air, presumably using leaks and vents in the basement to get that air into the flow. Geesh.

We have done extensive renovation and added enough returns that there is little draw down the stairs now.

I do have a heated basement, but will evaluate the need for taping in the basement and attic this spring.

Great site, Daox. Cannot believe I just found it from a Jough96Accord post on cleanmpg.

Daox · 03-07-10, 06:51 PM

Welcome to the site ksstathead. Great to have you here.

Feel free to post an intro. We'd love to hear about your home and what you've done with it.

Thats quite the situation with the basement door! I too noticed that while on the stairs plus the furnace being on there was a really decent draft. Not enough to slam a door, but enough to really feel standing there.

strider3700 · 03-22-10, 02:52 AM

I do heat my basement but I'm thinking of taking the time to tape all of the joints just to keep that air velocity high.

As well the outlets are where they are for a reason. Dumping hot air in the middle of my work area at ceiling level may technically make the room warmer but it's far from the most effective way to make me feel warm.

cantante · 05-02-10, 11:08 AM

Total total noob here - new to the site, and new to renovations. Right now we are not renovating so much as we are chasing problems. Today's problem is HVAC. There are leaks we have to deal with that make Daox's look dainty. One gap in particular - where there's a penny inserted in the photos here, we could shove a 2x2 in ours.

Lots of taping to do.

Years ago, I found an article on tapes and sealants that concluded that the absolute worst tape for taping ducts...is duct tape. I found the article again, here (I can't post links yet, sorry):

I am wondering if there are new appraches or standards to consider. The article is now 12 years old... green approaches preferred, but right now, filling the big gaps IS pretty green, almost regardless of how we do it.

Daox · 05-03-10, 07:01 AM

I would just use sheet metal and aluminum tape.

gasstingy · 05-27-10, 01:47 PM

I just got around to perusing the forums for morsels of info to help me on my way, and I find this thread.

Another example of why I thoroughly like this site.

I am often amazed at the quality(?) of work performed by a person paid to do a job. It's exactly why I try to do the work myself if at all possible. Most of the folks that regularly come to this site could do better work than the sloppiness you found. The energy savings you have just secured make you wonder why the previous owner hadn't done this and the light switch mod you recently took care of. To both of those improvements, I say "well done."

As for the extra velocity of the air coming out of your vents, it had to increase. You increased the volume of air that made it to the vent registers by removing so many outlets where the blower used to push the {somewhat} conditioned air. Less leakage means more, and better conditioned air to the registers. I'm certain there is a pleasant surprise coming on the power bill, if you can compare it to what it used to be.

Brian Abington · 07-10-10, 03:01 PM

Doax you showed in one pic were you filled a gap that put some of the aluminum tape on the wood...you could just put a strip of duct tape across the edge of the aluminum tape to hold it to the wood.

Of course your post is a few months old so if its still stuck it probably won't go any were.

bergenm · 07-29-10, 04:21 PM

Hey all,
My company sent me to a HERS Rater (Energy Star) class. We had a discussion about Sealing Products for ducts. The only product better for sealing ducts than the UL181 Aluminum Tape is UL181 Duct Mastic. UL181 Duct Mastic is a peanut butter like substance when you apply it. It hardens in a couple of days to a flexible hard rubbery seal. It sticks to metal, plastic, and wood. It remains affixed after ul181 tape has sweated off or cracked.

You apply it with a paint brush or gloved hand 1/4-3/8 thick. Push it right into the Crevasses. Larger gaps may need some mesh tape for a binder.

gasstingy · 07-29-10, 04:51 PM

Does the mastic require a cure time before running the HVAC, or can you keep it in operation the entire time?

03-07-10, 08:35 AM	#11
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Well, that last bit of duct sealing really did something. I'm not exactly sure why (feel free to comment), but the air coming out of the ducting is now coming out at a much higher velocity than before. I hadn't noticed this on any of the other taping sessions yet, but this is quite drastic. I imagine that is a good thing? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

03-07-10, 06:51 PM	#13
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Welcome to the site ksstathead. Great to have you here. Feel free to post an intro. We'd love to hear about your home and what you've done with it. Thats quite the situation with the basement door! I too noticed that while on the stairs plus the furnace being on there was a really decent draft. Not enough to slam a door, but enough to really feel standing there. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

05-03-10, 07:01 AM	#16
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I would just use sheet metal and aluminum tape. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

03-07-10, 03:43 PM	#12
ksstathead Learning to live better Join Date: Mar 2010 Location: Oz Posts: 13 Thanks: 0 Thanked 0 Times in 0 Posts	Our 1948-vintage home was retrofitted with central heat & air decades ago, using the uninsulated exterior wall cavities for return air. Likely a code violation even when done, I don't know. Of course, at a later point, someone blew in insulation into the walls. Two great things do not always make a peanut butter cup. We bought it in '98, and the HVAC kicking on would SLAM the basement door closed, as the stairway had become the primary return air, presumably using leaks and vents in the basement to get that air into the flow. Geesh. We have done extensive renovation and added enough returns that there is little draw down the stairs now. I do have a heated basement, but will evaluate the need for taping in the basement and attic this spring. Great site, Daox. Cannot believe I just found it from a Jough96Accord post on cleanmpg.

03-22-10, 02:52 AM	#14
strider3700 Master EcoRenovator Join Date: Dec 2008 Location: Vancouver Island BC Posts: 745 Thanks: 23 Thanked 37 Times in 30 Posts	I do heat my basement but I'm thinking of taking the time to tape all of the joints just to keep that air velocity high. As well the outlets are where they are for a reason. Dumping hot air in the middle of my work area at ceiling level may technically make the room warmer but it's far from the most effective way to make me feel warm.

05-02-10, 11:08 AM	#15
cantante Lurking Renovator Join Date: May 2010 Location: Indiana Posts: 1 Thanks: 0 Thanked 0 Times in 0 Posts	Total total noob here - new to the site, and new to renovations. Right now we are not renovating so much as we are chasing problems. Today's problem is HVAC. There are leaks we have to deal with that make Daox's look dainty. One gap in particular - where there's a penny inserted in the photos here, we could shove a 2x2 in ours. Lots of taping to do. Years ago, I found an article on tapes and sealants that concluded that the absolute worst tape for taping ducts...is duct tape. I found the article again, here (I can't post links yet, sorry): I am wondering if there are new appraches or standards to consider. The article is now 12 years old... green approaches preferred, but right now, filling the big gaps IS pretty green, almost regardless of how we do it.

05-27-10, 01:47 PM	#17
gasstingy Journeyman EcoRenovator Join Date: Feb 2010 Location: Arab, AL Posts: 491 Thanks: 109 Thanked 49 Times in 43 Posts	I just got around to perusing the forums for morsels of info to help me on my way, and I find this thread. Another example of why I thoroughly like this site. I am often amazed at the quality(?) of work performed by a person paid to do a job. It's exactly why I try to do the work myself if at all possible. Most of the folks that regularly come to this site could do better work than the sloppiness you found. The energy savings you have just secured make you wonder why the previous owner hadn't done this and the light switch mod you recently took care of. To both of those improvements, I say "well done." As for the extra velocity of the air coming out of your vents, it had to increase. You increased the volume of air that made it to the vent registers by removing so many outlets where the blower used to push the {somewhat} conditioned air. Less leakage means more, and better conditioned air to the registers. I'm certain there is a pleasant surprise coming on the power bill, if you can compare it to what it used to be.

07-10-10, 03:01 PM	#18
Brian Abington Lurking Renovator Join Date: Jul 2010 Posts: 4 Thanks: 0 Thanked 0 Times in 0 Posts	Doax you showed in one pic were you filled a gap that put some of the aluminum tape on the wood...you could just put a strip of duct tape across the edge of the aluminum tape to hold it to the wood. Of course your post is a few months old so if its still stuck it probably won't go any were.

07-29-10, 04:21 PM	#19
bergenm Eco-Geek Join Date: Jul 2010 Posts: 8 Thanks: 0 Thanked 2 Times in 2 Posts	Hey all, My company sent me to a HERS Rater (Energy Star) class. We had a discussion about Sealing Products for ducts. The only product better for sealing ducts than the UL181 Aluminum Tape is UL181 Duct Mastic. UL181 Duct Mastic is a peanut butter like substance when you apply it. It hardens in a couple of days to a flexible hard rubbery seal. It sticks to metal, plastic, and wood. It remains affixed after ul181 tape has sweated off or cracked. You apply it with a paint brush or gloved hand 1/4-3/8 thick. Push it right into the Crevasses. Larger gaps may need some mesh tape for a binder.

07-29-10, 04:51 PM	#20
gasstingy Journeyman EcoRenovator Join Date: Feb 2010 Location: Arab, AL Posts: 491 Thanks: 109 Thanked 49 Times in 43 Posts	Does the mastic require a cure time before running the HVAC, or can you keep it in operation the entire time?