dryer vent seal / safety question

15 years ago

First, I am an idiot! I want to be SAFE and end up making things worse I guess. So now I ask you guys...

1) Our dryer is in our unfinshed basement. When we moved in 2 years ago I noticed a bunch of lint mixed with with the fiber glass insulation batts where the dryer vent exits the house by the rim joist. I immediatley disconnected to loose plastic vent hose and installed a ridgid metal one with 2 - 90 degree bends on each end. This vent was bought at HD and was the type you sort of had to roll into a tube shape and snap together...I remember that was chore itself...for me anyway! I had always heard that platic was unsafe to use metal and I wanted to make sure everything was safe! Well. I actually needed 2 sections of pipe to run from the floor (bottom of dryer) out the rim joist, say 7.5 feet. I assembled the to pieces, slid them into each other and secured them with 2 screws. I am now being told to removed the screws because the can catch lint and become a fire hazard! Ok, if I remove the screws, what is the exact type of tape I am suppse to use to insure the pipes do not slip apart? I assume it must be some sort of fireproof tape since those pipes get hot....

2) I notice a draft in the dryer area by the ceiling. Can I spray foam the area where the duct leaves the house? Again, the pipes get hot. If yes, is there a specific foam type I should use? I also have some black fireproof chimney stuff but the foam would be easier to work with.

3) Whenever we open the dryer door cold air spews out! We have the old fashion metal flapper outside the house. Air evedently is getting. Is there a better, again SAFE, product that would stop that air from getting into the dryer from the outside?

Thanks all!!!!

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Comments (15)

rjoh878646
15 years ago
Take out the screws and tape it together with metal foil tape used on duct work. Where it exits the house caulk it ont inside and outside.

the link below is for a replacement for your flapper. I have one. It has a little cup that the dryer exhaust pushes up and when the dryer is not running closes off the pipe. The lid comes off to clean out lint.

Here is a link that might be useful: dryer vent seal
andrelaplume2
Original Author
15 years ago
Cool! Question.....If snow or something rests on the top, would than not stop the top from popping? If so, wouldn't the air back up and damage something or cause a fire hazzard? Do you notice a lot less cold air in your dryer...there are times we take the close out late in the day and they are freezing!

You say to caulk inside and out. Use the fire stuff I have left over from my chimney project or use spray foam?
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rufusdoofus
15 years ago
No, the top of the hood does not pop up for venting. It stays closed unless unlatched for cleaning. The shuttle cap is inside, it floats upward and air blows out around the bottom.
pjb999
15 years ago
Downside to that hood system is, it's all outside so the air is going to get pretty cold anyway, although a better seal is probably going to help somewhat.

Andre, if I recall you're in Quebec? I'm in BC so our codes should be similar. You were right to go to the metal ducts, plastic is not legal any more and not a good idea. I fortunately learned on this forum about not using screws, and the hvac foil tape is what you want to use. You could probably caulk the holes with the fireplace caulk but (and I don't know if this would be code or not) you could probably get away with using silicone, especially automotive. It may not be legal strictly but by the time it reached its flash point or whatever, you would have bigger issues to deal with.

I would recommend this, because it blocks the cold air at the point of entry rather than when it's already outside.....http://www.dundasjafine.com/products/accessories/draftblocker.html

Remember you should make the ducting so that it can be disassembled and cleaned periodically, it should be taken apart and the lint removed, just like sweeping a chimney. Not only will it save energy, it will reduce fire risk.

Here is a link that might be useful: Draftblocker
andrelaplume2
Original Author
15 years ago
Thanks. I am in PA, USA.
pjb999
15 years ago
OOps. my bad. Anyway, I still think the flapper I described is better. Haven't gotten around to putting mine in yet...
frodo_2009
15 years ago
I have been lurking here in my corner..i like the fitting
i an going to get one for my place, i have the cheesey 5 dollar flapper. that sticks openor closed.
thanks for info
mrmichaeljmoore
15 years ago
Just a follow up question...

Whay cant you use PVC for dyer venting?

I have my dryer vented with PVC and never had a problem...
brickeyee
15 years ago
"Whay cant you use PVC for dyer venting?"

Cause the code requires rigid metal except for a single section of flex from the dryer to the metal is allowed.

Gas driers are definitely to hot for plastic, and the electric ones are not far behind.
pjb999
15 years ago
I'm not sure if it was a retroactive order or the previous owners of my house just got it right, but originally (probably going back to when house was built in '80's) dryer was vented with vinyl, they abandoned it and ran gal steel vent through the garage and outside. I never thought of the risks of vinyl til reading gardenweb, makes sense. Vinyl is a fire hazard, as it's quite easy for dryer lint to catch fire. If it happens in a vinyl vent, the vent will melt. Metal will contain it, at least for a bit.

This is why we're supposed to clean the vent now and then.

Or the vinyl might just melt or soften to the point of tearing if things got too hot (stuck flapper for example) and then dust and moisture would be escaping inside structure, which would not be a good thing.
bstarz
15 years ago
1. Plastic flex and alum flex have more resistance than alum drier vent.
2. Gas driers have a higher exhaust temp than electric driers.
3. The best way to vent any drier is with alum drier vent and alum tape the joints.
4. 1 elbow is equal to 5 feet of pipe.
5. Clean and check yearly.
manhattan42
15 years ago
"Whay cant you use PVC for dyer venting?

I have my dryer vented with PVC and never had a problem..."

PVC also develops a static charge as air flows through it.

This can cause lint to cling to the inside of the pipe as air flows through it.

This can lead to eventual blockage of the pipe and a fire.
alphonse
15 years ago
Gotta love the ironies arising from municipal codes. PVC is banned, but the dryer vent seal in the link is ABS, which was banned years ago (here anyway).
mrmichaeljmoore
15 years ago
All this talk about dryer vent....so I decided to clean my today.

As I stated above, I use PVC pipe to vent my dryer. Also stated above, apparently this is against code.

But, as I was taking the piping apart today to clean it, I noticed the fitting off the back of the dryer is plastic. Plus, inside the dryer vent fitting, there is a flywheel (looks like a hamster wheel), which is also plastic.....

so, is the code against using plastic/pvc need to be updated?

(I am not a plumber, electrician or any type of contractor...just a homeowner)

The dryer is a Fisher and Paykel Top Loading Dryer.
pjb999
15 years ago
If the appliance got a UL approval with the plastic fittings, I guess it's still ok. The venting from there on, though, needs to be metal, no screws, foil tape only.