Jenn Air Stovetop - Backdraft. Thermal Break?

I've got a Jenn Air stove with a downdraft fan vented to the outside. In the winter, cold air seeps in from the outside (I do have a louver mounted on the outside wall). Sometimes when it's really cold you can freeze a small drop of water on the stovetop. I usually need to put a dishtowel over the vent which helps a bit.
The Jenn Air website suggests installing something called a 'thermal break' which is described as a non-metallic (so as not to conduct heat) piece in the air duct as close as possible to the outside. No one at my local stores has ever heard of this device.
Does anyone out there know what this looks like and possible where else I could find one?
Thanks in advance! KZ
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A thermal break is probably just a piece of pvc in the run to stop the transference of heat/cold. You probably need an new damper outside. The damper on my exhaust fan does not work very well especially in windy weather. I live in a pretty temperate climate so I am not going to do anything about it.
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Found this on a search:
"Cold weather installations require an additional backdraft damper installed to minimize backward cold airflow. In addition, a non-metallic thermal break is needed to minimize conduction of cold airflow through the ductwork. The damper should be in the cold air side of the thermal break, and the break should be as close as possible to where the ducting enters the heated portion of the house."
I read this several times. Lot of double talk...OK. Thermal = heat and break = break. So break the heat. Simple!
I built my own thermal break for my Jenn-Air and didn't know to call it that - I cut a piece of heavy cardboard and keep it wedged in (where the big hole is, behind the woven metal filter.
In really, really cold weather, I wrap a piece of aluminum foil over the top vent and fit it under the edges and re-insert the top vent piece. Pull it out when you want to grill or use the fan.
May not be pretty but it works. The cardboard is not visible so unless it is very cold, you don't need the aluminum foil part.
I have a real love/hate with the Jenn-Air. LOVE the ability to grill inside.
KZ wrote:

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Thanks for the reply. Sounds like you do the same with foil that I do with a dish towel. The only problem with the cardboard idea is that you can't use the exhaust fan when the cardboard is blocking the exhaust duct. I found the same text in my search but I interpreted that the 'additional backdraft damper' would be a hinged affair of some sort which open and allow exhaust to exit the house, but not allow cold air in.
KZ

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You remove the cardboard when you are using the fan. The cardboard does not show and keeps the cold air out when you are not using the fan. So it works better than just covering the top vent.
If you find something that works better, please post.
P.S. I bought most of the replacement parts for the top, to hold and put on when I sell this house. I have used Jenn-Air grill tops (in 4 other houses) for over 30 years and this is the only one I've had that the top pieces are of such poor quality. Only gas Jenn-Air I've ever had so that might be the problem.
KZ wrote:

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don't they make some sort of flapper for dryer vents that could be used?
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I've seen those on the outside wall, just like the stove exhaust damper but I haven't ever seen an additional one that is inside the ductwork. The inside of my dryer is cold in the winter but the dryer door seems to do a good job of sealing it off from getting in the house.
Perhaps not all dampers are created equal. Mine have thin plastic louvers which open and close with the air going out. I've also seen ones which have more of a circular plastic flapper plus a rain-hood of some sort, I think maybe I'll give one of those a try.
Here's a different one: http://www.improvementscatalog.com/product.asp?product6756zz&dept_id 400&cm_ven=INKTOMI&cm_cat=Laundry_Maintenance&cm_pla=Dryer_Vent&cm_ite6756zz&code=macs=MPINK04
KZ
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KZ wrote:

dryer. I don't know what the air pressure of the stove vent is, so I don't know whether it would provide enough to lift that shuttle inside the vent. I had to move the vent outlet last year to make room for an addition and I went with a different kind, or else I would still have it.
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