Find out how to repair leaking ducts with duct tape. Learn why regular duct tape won't work properly, and why you should instead get UL 181 tape. Get tips on conducting a duct blaster test and having an energy audit of your heating system done.
LESLIE: Now we’re going to take a call from my neck of the woods in New York where Ellen has a question about duct tape  and it’s many interesting uses.
Ellen, how can we help?
ELLEN: Oh, hi. I was reading in The Money Pit email newsletter that I get that you recommended this silver tape to put on ducts if there were some air leaks .
ELLEN: And it says you recommended UL 121.
TOM: 181. Yes. UL 181 tape. It’s different than regular duct tape. Duct tape is great for everything except one thing: ducts.
LESLIE: Except for ducts.
TOM: Yeah. Because what happens, Ellen, is the adhesive that’s on standard duct tape, once you put it on heating ducts , it dries out fairly quickly or even in air conditioning ducts up in the attic that gets really hot in the summer. The adhesive on that dries out. So the solution is a special type of tape called UL 181 tape and basically it’s duct tape where you put it on – it’s sticky on one side – and then you peel off a protective coating and you actually rub it down so it really adheres well to the duct. There’s a device that looks like a credit card that basically you use to rub it down and seal it real well. And that has the special kind of adhesive in there that’s not going to fall out and that’s important because duct leakage is a huge source of energy loss because, you know, you’re not making any money if all of that hot air in the winter is leaking into your attic or the cold air in the summer is leaking into your attic. You want all of that heated air or cooled air to be delivered right to the rooms you need it and that’s why you need to use the proper type of tape for those ducts.
ELLEN: Now, the only thing I could find was UL 723. Does the number on it make a difference?
LESLIE: The UL 181 tape, which is perfect for your ducts – there’s also UL 723, which is even better than 181 because it does everything you need for the duct work but it will also prevent or help you against flame and smoke damage as well. So it does it even one step further.
ELLEN: Oh, that’s great. That’s great because – yeah, because I couldn’t find the 121 – or the 181.
TOM: So many numbers, so little time.
ELLEN: Yeah. (Tom chuckles) Wow, thank you so much. Because I mean I haven’t really been able to detect if there’s air coming out or not but I have a 40-year-old furnace and there’s a lot of connections in the vents. So I thought I would get this and when we turn on the heat on, to check that out.
TOM: You know, you can actually do a test that’s called a duct blaster test that can actually measure how much leakage is coming out of your ducts. I would check with your utility company, because many times they have energy auditors that do these for little or no cost, and find out about getting an energy audit of your heating system. And they may be able to actually do that and find the leaks for you and then you’ll know exactly where to attack them.
ELLEN: OK, great. Wow, thank you so much. You’ve been a great help.
TOM: You’re welcome. Thanks for calling 1-888-MONEY-PIT.