How can we prevent condensation, and eventually ice, to form on the clothes dryer exhaust duct?
I live in a newly renovated and insulated house in Montreal, Quebec, Canada, where the minimum temperature range between – 20 to – 25 F. My clothes dryer exhaust duct is about 1 feet long and connect the clothes dryer directly outside. When not in use, condensation forms on the duct, drips on the hard wood floor, and eventually, ice forms on the duct. All of this is quite logical, but I have never heard of such a problem before. The house temperature is about 70 F. There is not a lot of air circulation between the exterior wall and the dryer so I’ve installed a small fan in front of it. It is not perfect, but it helps. However, I don’t think it is the best solution.
Thanks for any suggestions!
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Replies
Pretty bloody cold in your neck of the woods! First, seal the dryer duct with mastic at all joints and then make sure that it is slightly tipped to drain to the outside. Second, make sure you have a good seal on your one-way flapper on the exterior hood vent. You used to be able to get an electronic dryer vent hood that actually sealed driven by a motor, but it was too expensive and the manufacturer dropped it. It is pretty cold here in Vermont and when it blows, our dryer vent flapper "flaps." I installed a little weight on the flapper (but not enough to affect its full opening when the dryer is running) that helps keep it closed.
Marie-Hélène,
I live a little south of you, in the mountains of northern Vermont, and (according to the radio weather reports) my town is always just a little colder than Montreal. In addition to following Peter's advice, I suggest a top quality dryer vent termination. This is the one I use:
http://www.energyfederation.org/consumer/default.php/cPath/30_742_110
That way less outdoor air will enter your duct.
My brother-in-law from Ontario send me one of these - it's much better than the ones sold by home centers here in Massachusetts. Instead of a flapper, it uses a styrofoam ball to provide an air-tight seal. I snipped off every other tine of the exhaust grill to minimize lint build-up.
Broan-NuTone Eco-Vent
http://reviews.homedepot.ca/1998/902889/reviews.htm
I came across this vent a while back when I was thinking about dealing with the same issue. I haven't tried it yet. I don't have enough clearance as my dryer vent exits below the soffit. Though I think I'll be moving the vent so may give it a try once I have.
http://www.theresourcestore.ca/proddetail.php?prod=HPDV-21000
I presently use a vent made out of steel that is manufactured in Quebec that I bought at Reno-Depot. The flap is heavy enough that it should close tight compared to plastic flaps. Though their may be some conduction heat loss because it is made of steel?
Andrew, that's the Heartland Dryer Vent Cap that Martin linked to. It's the best on the market.
If you're venting the dryer under the soffit and have soffit vents into the attic, then you're introducing significant amounts of moisture into a cold condensing surface area. It is generally unwise to vent any exhaust fan to or near the soffits.
Thank you very much to all of you for your suggestions!