Are there any range exhaust vent covers-

[rgruby]

Hi,

I know a lot of you are settling down to a nice turkey dinner right about now. Happy Thanksgiving!

Ok, just to be clear, I'm talking about when the vent from your range exhaust goes from the inside of your home to the outside, on the outside there is some sort of housing to prevent the elements from entering, but which allows the exhaust to exit. The part that's on the outside is what I'm talking about.

And mine doesn't work very well. It's just a cheap metal box with a single flap that doesn't seat properly and/or isn't heavy enough. The result is that it flaps noisily when it is windy, and never really closes. So, in addition to allowing the possibility of letting critters in (there's no screen), it also lets in an amazing amount of cold air - it feels like there's a window open in our kitchen in the winter. Not good.

So, anybody have any suggestions on makes or brands that are functional for this use?

Oh, I need one built for an 8" opening.

I recently read of something called an eco-vent for dryers (which I think are usually 4" diameter openings). Does anything like this exist for larger sized openings?

Thanks!

Geoff Ruby

[annieC]

Our solution has been in really cold weather, is to run our exhaust fan on its lowest setting (it has 10 settings). The idea being that at least if air is moving out, no cold air can come in-lol. We really need to come up with a better solution of some sort- if I come across anything, I'll let you know.

[mrbigjas]

i was hoping you'd get more answers to this, since we have the same problem. we have a small house and the kitchen isn't a separate room or anything, so that cold breeze coming in really makes a difference.

in our case, our vent is right outside our back door, and what i do is take a chunk of fiberglass insulation that is about the size of the vent cover, tie it up in a couple of plastic bags, and jam it in the vent when we're not using it. and the first thing i do when i start to cook is take it out. it's totally hoopty, but you gotta do what you gotta do...

[rgruby]

The vent I currently have appears to be this one: http://www.drillspot.com/products/47018/Broan_643_Wall_Cap

It's pretty much the only one I can come up with in an 8" size after the better part of an hour searching the web.

The dry eco-vent thingey is something like this: http://www.green-talk.com/2007/09/24/is-yo...ing-you-a-cold/

It apparently only works in low Cfm applications though, so no good for a kitchen exhaust.

I've also started putting some insulation in mine when not in use. Helps a bit.

I might try gluing some weights on - maybe just start with a bit of duct tape - to see if that will keep it closed when it's not in use, but allow it to open fully when I turn it on.

I'm finding it a bit weird (and frustrating) that there doesn't appear to really be anything out there.

Oh, also found out that a screen is NOT recommended - apparently cuts down the airflow too much.

The search continues.

Cheers,

Geoff Ruby

[qrn]

The vent I currently have appears to be this one: http://www.drillspot.com/products/47018/Broan_643_Wall_Cap

It's pretty much the only one I can come up with in an 8" size after the better part of an hour searching the web.

The dry eco-vent thingey is something like this: http://www.green-talk.com/2007/09/24/is-yo...ing-you-a-cold/

It apparently only works in low Cfm applications though, so no good for a kitchen exhaust.

I've also started putting some insulation in mine when not in use. Helps a bit.

I might try gluing some weights on - maybe just start with a bit of duct tape - to see if that will keep it closed when it's not in use, but allow it to open fully when I turn it on.

I'm finding it a bit weird (and frustrating) that there doesn't appear to really be anything out there.

Oh, also found out that a screen is NOT recommended  - apparently cuts down the airflow too much.

The search continues.

Cheers,

Geoff Ruby

←

Turn it upside down, Then fabricate a rectangular cover out of light tin or alum. attach the thing on a couple of screws at the sides, in a pivot arrangement, so it will swivel up to open. The blast of air from the fan will automatically open it..My fan unit is on the roof and it has one that is vertical, and when the fan starts it swings out to open,,,If that is not clear I will draw somthing up and scan it and post it...

Bud

[rgruby]

Turn it upside down, Then fabricate a rectangular cover out of light tin or alum. attach the thing on a couple of screws at the sides, in a pivot arrangement, so it will swivel up to open. The blast of air from the fan will automatically open it..My fan unit is on the roof and it has one that is vertical, and when the fan starts it swings out to open,,,If that is not clear I will draw somthing up and scan it and post it...

Bud

←

Thanks, I think I get the idea. I'm not sure it would solve the problem though, and I think it might let rain in as well. Might help a bit though - in essence it just switches the flap location to the top and uses the flap to form an enclosed "box" when the fan isn't on. Seems like it might flap around less just from the wind. Hmmm. Let me think about this for a bit.

Cheers,

Geoff Ruby

[qrn]

Turn it upside down, Then fabricate a rectangular cover out of light tin or alum. attach the thing on a couple of screws at the sides, in a pivot arrangement, so it will swivel up to open. The blast of air from the fan will automatically open it..My fan unit is on the roof and it has one that is vertical, and when the fan starts it swings out to open,,,If that is not clear I will draw somthing up and scan it and post it...

Bud

←

Thanks, I think I get the idea. I'm not sure it would solve the problem though, and I think it might let rain in as well. Might help a bit though - in essence it just switches the flap location to the top and uses the flap to form an enclosed "box" when the fan isn't on. Seems like it might flap around less just from the wind. Hmmm. Let me think about this for a bit.

Cheers,

Geoff Ruby

←

As I think about it more ,you can just turn it so the slot is vertical and then hinge it at the top. Then if it snows or rains on it it will not keep it from working (that is how mine is)

A hole on each side of the outlet , a thin 1/8" rod between the holes and the plate attached to the rod.so it can open....

Bud

[LindaK]

oh my. is this a universal problem? I'm starting to specify items for my kitchen renovation and would love to hear more on this. I just spent a lot of money on new storm windows and don't want to the exhaust vent to negate that. Since the heat is on 6 months of the year here, this could be expensive.

[Beanie]

I've had this problem for years with a Jenn-Air downdraft range that vents through a crawl space to the outside. I finally stuffed insulation into the duct and rarely use the exhaust fan. There's alot of discussion about this problem all over the web, including this site.

In cold weather locations, a non-metallic thermal break is supposed to be installed in the ductwork, as noted below:

Have a back draft damper installed, especially in cold weather installations to minimize backward cold airflow.  Additionally, a non-metallic thermal break is needed to minimize conduction of cold airflow through the ductwork. The damper should be in the cold air size of the thermal break and the thermal break should be as close as possible to where the ducting enters the heated portion of the house.

The above is from this web site.

Installing a thermal break was not standard practice when my unit was installed many years ago, and retrofitting it would be very difficult. I have done considerable research on the web and it appears that almost all installation manuals for ventilation systems now incorporate this recommendation. However, purchasing a "non-metallic thermal break" is another matter. Try finding it on the Jenn-Air web site (or any other appliance part store) without a part number and you're out of luck. I once saw a drawing and it appeared to be nothing more than a flexible plastic vent. Hard to believe it would even be effective.

I hope this information is helpful. If anyone has any other suggestions, I'd love to hear them.

[rgruby]

Given that the product I have seems to be the only thing out there for an 8" duct, and given the fact that even if it worked properly there's still only a rather flimsy piece of aluminum stopping the wind and cold from coming in, I rather suspect that it is a fairly common problem.

My outside bit is very close to the range hood inside - there's maybe 2 feet of ducting in there. I suspect that the short duct run in my place contributes to the problem. As does the lack of insulation in that wall. As does the fact that it's on the side of the house that gets hit with the prevailing winds most often.

Another idea floated out is to angle the base of the wall cap/ vent cover out a bit to try and get the flap to sit closed. ((The top would still be attached in the normal manner). It would also make the bottom of the flap a bit more exposed to the wind, so I'm not sure how effective it would be.

It might be a good idea to talk with your contractor and/or the place where you're buying your vent hood and at least see if they have any ideas or have encountered others that have had this situation and see if they found a reasonable solution.

I'm about out of ideas.

Cheers,

Geoff Ruby

[qrn]

There are two entirely different things that come into play here..

.first,is keeping the outside air from coming into the living space when the fan is not operational...That is the function of the "flap" or what ever you want to call it. .It closes the vent off to the outside, when ventilation is not needed...That is the assumption We have been working with here...

The second is

providing "make up air to the living space when the fan is operational...

If the living space is well sealed, and there is no "make up air" the fan will not exhaust.

if there is a furnace , hot water heater , fireplace. or leakage around windows and other places.these will provide the make up air. If they are the furnace and hot water heater, or fireplace,the carbon monxide they generate will be drawn into

the living space..

I have a 1000 cfm exhaust fan over the grill/stove. If I have a fire in the fireplace In the other room,and the fan on , the smoke will come out of the fireplace,not up the chimmny, and come over to the exhaust hood and out...Not a good thing!!Gotta open a window near the hood to provide make up air...Hope I have not muddied the water here!!