Can I use duct tape on ducts???

In My Humble Opinion
1

Kind of absurd-sounding, but from everything I’ve read, the stuff really was originally called Duck tape and wasn’t designed for ducts at all!!

The long version:
Here’s the situation: Dryer vent is connected to an in-the-wall duct, and hasn’t been working all that well, We pulled everything apart, got a surprising amount of crud just out of the dryer-to-wall bit, and went after the wall-to-outdoor part. Did some investigating and it’s that flexible mylar crap that is looped around a bunch of stuff in the furnace room, visibly full of heavy stuff in places, completely unsupported and sagging onto other stuff. The place is such a morass of tubes and pipes that I wonder if someone spilled a plate of spaghetti on the plans and couldn’t be bothered to clean it up.

Work with a dryer-vent cleaning kit got a fair bit of crud out, including some soggy lint that appears to date back to the Cretaceous period. Needless to say, we managed to poke a very small hole in one spot, which isn’t altogether bad as it’s letting some moisture drip out into a basin below. Lint tea - yum!

There actually is airflow through it as tested by blowing the shop-vac through, but a pretty major clog is still there.

Short version:
Small hole in flexible dryer vent hose inside. Can I just patch that with, well, duct tape (or something else) for the time being?

We are calling in a professional to fix / replace that bit of duct, this would just get the dryer working again for the time being.

2

I am no DIY expert but I say “Yes, no problem whatsoever!”

Duct tape is fairly waterproof - certainly enough to deal with condensation drips and very sticky. For a small repair it is fine. I actually used duct tape to hold the flexible duct from my cooker hood onto the vent, and it’s stuck firm for 18 months so far.

3

Just don’t use it on ducks. Doesn’t stick well to feathers.

4

Ironically, the one thing duct tape generally isn’t very good for is ducts. However, in this case because the hole is so small it should work just fine, especially since it is a temporary repair.

Just don’t call Central Services. They’ll have things all mucked up. Then again Harry Tuttle might intercept your call and fix your ducts up right. (obscure Brazil reference)

5

Yes. My dryer vent pipe is connected to the outside bit by duct tape. Worked just fine - for 6 months. Then I had to replace it because it fell off.

I am lazy and should be replacing it with foil tape, which is what the original professional installer used - I had to move the dryer temporarily and didn’t have foil tape handy.

6

It is illegal/against code to use “duct tape” on ducts. It is not sufficiently heat and flame-resistant, and it breaks down, leaving the joint unsealed and/or unattached, in a very short time.

Heating and ventilation ducts must be sealed with aluminum tape. Spensive stuff, but it sticks forever and will not break down.

7

But this is just a tumble dryer vent, right? Surely no problem.

8

Duck tape is really, really crappy stuff. It will fail in a very short period of time and then you have to clean it off and do it right.

Keep in mind that even if it’s “only” for a dryer vent, you need to be careful. Lint fires in vents happen all the time and metal tape gives a much better safety margin. (Which is also why it’s a really good idea to avoid those rubbery dryer ducts.)

Foil tape is just so handy for so many purposes that it’s practically an essential for a DIYer’s tool box.

Keep in mind that many stores carry two kinds: A “plain” type that doesn’t meet code and a type with red printing on it that specifies that it meets code.

9

As ftg said, you really want to contain dryer exhaust so that lint does not leak out of the joints and form a fluffy time bomb waiting to burn your house down. It may seem tame and unimportant, but… try this. Take the next lint pillow you peel out of your dryer filter out into a very safe place for a small fire (like a cold barbeque or the middle of your lawn). Touch a match to it. If it lasts more than about five seconds, you don’t clean your dryer filter often enough.

Lint is flammable to the point of being explosive. A ten-dollar roll of tape to keep the duct sealed is cheap.

10

for a short term temporary fix duct tape is just fine.

for replacement metal flex duct is more durable. plastic flex duct lets you see obstructions inside, which was important in this case.

you want to have the duct run straight and smooth as possible, dips allow lint to collect. lint blockage keeps the dryer from being efficient and might allow lint to later collect where it might be a fire hazard (in or near the dryer). also in a cold climate water could condense in the dips. a louvered dryer vent is also good in cold climates to save on home heat from escaping.

11

Plastic flexible ducts are terrible. I never hook up a dryer with one. There is flexible metal duct, but it makes much more sense to buy short sections of 4" metal duct and adjustable elbows. Tape each joint with metal tape, and you’re set for years. The interior is nice and smooth and it’s intended to handle hot air.

12

But the real question is…which fancy duct tape are you going to use?

13

Duct tape on dryer vents is problematic, but not for the reasons previously cited. Make absolutely sure that the area you want to patch is ‘eat off it’ clean, because any amount of lint on the mating surfaces will keep the tape from sealing.

Been there and done that. New dryer hose is cheap, BTW.

14

In our case, the dryer-to-wall connection uses the flexible metal duct, but the part in the furnace room uses the mylar stuff. I don’t think the short rigid / joint system you propose would work there, because it is so convoluted, but possibly the flexible metal stuff would.

It’s truly stunning, what a bad job they did. They could have done a fairly straight run to the back of the house, using all rigid ducting. But no, they had to do an offset.

Imagine the house’s back faces north, and imagine a grid of 4x4 is the house. The dryer is in row 2, column 3. A duct going down behind the dryer should come out at the northern side of row 1, column 3.

Instead, this thing goes down, crosses from 2,3 to 2,2 in the furnace room (looping around other stuff in there), and then goes north and exits at row 1, column 2.

Now, neighbors have the same floorplan as we do but their backyard is different - so where we have a bay window at 1,3. they have an actual french door and stairs. So in their place, the exit at 1,3 won’t work. In our case, there’s NO REASON for it not to go straight back.

Last night when I got home from work, I checked the container we have catching water. A half cup of “lint tea” (I wonder if I cultured it, what it would grow!!).

I poked around the bit of flexible ducting that felt super-heavy (and wasn’t right by the small hole) and as I jiggled it, more water started dripping out of the hole - which made sense as it was probably lower than the hole. More jiggling, and replacing of the water container, and by this morning nearly a quart had dripped out. Yeccch!!! And the really heavy section of the duct is MUCH lighter.

I’ll look into some of the real foil tape for the patch - what would it be called? “foil duct tape” or something? We’ve got a pro coming in to look at longer-term solutions but in the meantime we would like to be able to do laundry!!

15

I just bought some at Home Depot the other day. I found it located near the rigid foam insulation. 3 bucks a roll. It’s labeled “Foil Tape”.
Stuff is incredibly sticky, I used my mouth as a third hand when pulling off the backing. It took a piece of skin off my lips when I removed it.

16

That’s probably the stuff which doesn’t meet code for ducts (which would be in the HVAC section). That foil tape is more for insulation sealing, etc. where there isn’t a heat source. Did it have printing on the tape itself specifying that it meets code or is it just blank tape?

17

[quote=“Colophon, post:7, topic:645864”]

But this is just a tumble dryer vent, right? Surely no problem.[/QUOTE

I do not know about other jurisdictions but here in Calgary the old flexible vinyl of foil dryer vents are no longer code. They are more prone to clogging and can be a fire hazard. I think the main issue is probably CO poisoning potential with a clogged hose combined with a natural gas dryer. Those dryer vents actually can get pretty hot, certainly hotter than a heating vent. You can still buy the old stuff but the approved product is either rigid vent or coiled aluminum flex vent, sealed with aluminum tape if necessary

This is just a short term fix so it should not be a problem and if the duct tape is just going on Mylar hose anyway. Its not like it is going to be any worse than the Mylar itself.

For what its worth I have seen a lot of old, professionally installed heating duct ‘sealed’ with what is essentially paper masking tape, which has got to be worse than duct tape