# Cook top exhaust fan



## drtbk4ever (Dec 29, 2008)

Is it possible your exhaust fan just filters the air and exhausts into the home? Or maybe it exhausts through the wall? 

That would explain why there is no duct to the roof.

I cut a hole in my roof for my range hood fan ducting. It wasn't pretty. Installed the thingy on the roof and it didn't blow off in a wild wind storm we had. I then ran the venting through the ceiling myself. I think I got it straight and water tight. It is insulated in the attic. I just haven't got the hood installed yet.

So maybe you can do it.


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## eagertolearn (Jan 13, 2010)

I really dont think that it just filters it and returns the air but how do i tell? 

Also if i do have to vent it out the roof it shares a wall with my bathroom which also has no exhaust fan and id like to add one, can i use the same vent for both?


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## drtbk4ever (Dec 29, 2008)

Good questions, which are well out of my expertise. But I will share my thoughts anyhow.

Is your exhaust fan mounted under a cabinet? Turn on the fan and open the cabinet and feel to see if there is any air flow in the cabinet. If you can see the top of the cabinet, try to determine if there is any air flowing around the top of cabinets. And if possible go into the attic with that fan on and see if there is air blowing in there.

As far as using the same venting for both the bath and range exhaust I suppose you could do that but I would be concerned with backflow where the kitchen exhaust gets into the bathroom and vice versa. I would also think the range hood exhaust would be a larger diameter than the bathroom vent. But I am JUST GUESSING.

Could you post a photo of the exhaust fan and what is above it?

We'll get some experts in here soon with the correct answers.


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## Daniel Holzman (Mar 10, 2009)

Oddlly enough I had the same problem with the exhaust fan in my kitchen. It vented into the wall behind the cooktop, not too efficient. I connected an appropriate length of 4 inch diameter galvanized steel piping through my garage to an outside wall, and installed a vent cover. Eventually I replace the vent fan with an over the cooktop hood, still using the galvanized piping exhaust run. You can certainly vent through the roof, however cutting a hole in the roof and correctly flashing it is more difficult than running the vent pipe out the side of the garage.


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## daveb1 (Jan 15, 2010)

Post some pictures of the fan ,the attic above the stove,the outside of your house near the stove, the outside roof above the stove area and a rough floor plan sketch of your kitchen labelling inside and outside walls.


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## CallMeChaz (Feb 6, 2010)

Do NOT vent them into the same duct! When you turn either one on, it will blow out the other fan. The smell of bacon in the bathroom might not be too bad, but the alternative in the kitchen should be obvious. 

I might be missing something, but this sounds like a no-brainer. If you can see the stove duct in the attic covered with insulation, you have to vent it through the roof. You may be able to put an elbow on it and run it out the gable wall. Either way, you need to be able to cut through the roof or wall with some confidence, and seal it properly. 

Is this is a vent hood under a cabinet against an outside wall? Some such hoods have the option to vent upwards, or directly through the wall. Still you need to make the cut to the outside.

Putting a wall or roof vent in is not rocket science, but doing it wrong guarantees a leak. What is your apprehension? Lack of instruction; lack of tools; fear of the unknow? This is not exactly simple, but do-able. It's your move.


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## Thurman (Feb 9, 2009)

A lot of range exhaust units built today and sold at apron stores are what I call "universal", and can be exhausted either "internal", or "external". Look at your unit straight on. Do you see "louvers/open grills" at the top of the unit? If so, then most likely this either a universal or dedicated internally exhausted unit. Let's say there are: Turn the unit on high, feel to see if there is air being blown out of these grills. If there is--it's internally exhausted-the air is pulled through a grease filter and returned to the room. IF not. Is there a cabinet above the unit? You stated there was ductwork in the attic covered. There is a baffle which must be moved within the unit to direct airflow either internally or externally-into the ductwork. I'm wondering if the air is being directed into a blind duct. More confusion--not likely--the air is vented out the back side, look into that and eliminate the chance. *IF* you determine you are a competent DIY person: Remove the fan cover, remove the fan unit, then look to see if the baffle is installed-or pieces removed-to direct air flow in what direction. Once you know this you can proceed to direct the air as you choose. I do agree not to tie any exhaust ducts into each other for proper drafting. Around here it is a code violation. Good Luck, David


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