# Range Vent Ductwork from interior wall 2-story house



## RLoureiro (Mar 1, 2021)

Hello,

I am planning to install a gas stovetop against an interior wall.  I am replacing a ceramic stovetop with a downdraft that goes under the slab, under the kitchen, and out to the exterior wall.  I plan on installing a vent-a-hood, and therefore cannot use the existing downdraft ventilation.  I therefore need to go over the kitchen (in the subfloor) and out to the exterior wall.  I will have room to install an 8" vent.

My problem/concern is that by venting via the ceiling, I will be exiting the house over the kitchen window.  I do not believe that I should be exhausting over the window.

I cannot vent vertically due to being under the upstairs bedrooms. 

What options do I have?

Regards, Rob


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## steveray (Mar 2, 2021)

As it is your vent and your window, probably not a code issue as the hood/ vent is likely not required and not exactly noxious...But I have never had your cooking....


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## fatboy (Mar 2, 2021)

Manufacturers specs will drive the location of the exhaust. 

M1503.3 Exhaust discharge. Domestic cooking exhaust equipment shall discharge to the outdoors through a duct. The duct shall have a smooth interior surface, shall be air tight, shall be equipped with a backdraft damper and shall be independent of all other exhaust systems. Ducts serving domestic cooking exhaust equipment shall not terminate in an attic or crawl space or areas inside the building.

Exception: Where installed in accordance with the manufacturer’s instructions, and where mechanical or natural ventilation is otherwise provided, listed and labeled ductless range hoods shall not be required to discharge to the outdoors.


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## RLoureiro (Mar 2, 2021)

fatboy said:


> Manufacturers specs will drive the location of the exhaust.
> 
> M1503.3 Exhaust discharge. Domestic cooking exhaust equipment shall discharge to the outdoors through a duct. The duct shall have a smooth interior surface, shall be air tight, shall be equipped with a backdraft damper and shall be independent of all other exhaust systems. Ducts serving domestic cooking exhaust equipment shall not terminate in an attic or crawl space or areas inside the building.
> 
> Exception: Where installed in accordance with the manufacturer’s instructions, and where mechanical or natural ventilation is otherwise provided, listed and labeled ductless range hoods shall not be required to discharge to the outdoors.


Your manufacturers spec does not provide feedback on whether or not it is acceptable to have the exterior vent over the kitchen window, or if there are any recommendations for a better location.


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## mtlogcabin (Mar 3, 2021)

How often is the window even opened?


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## JCraver (Mar 3, 2021)

3 feet is always the answer for residential exhaust, no?  It has to discharge at least 3' away from the window and from any other opening back in to the building.  

2015 IRC:

*M1501.1 Outdoor discharge*. The air removed by every mechanical exhaust system shall be discharged to the outdoors in accordance with Section M1506.3. Air shall not be exhausted into an attic, soffit, ridge vent or crawl space.
*Exception:* Whole-house ventilation-type attic fans that discharge into the attic space of dwelling units having private attics shall be permitted.

*M1506.3 Exhaust openings.* Air exhaust openings shall terminate not less than 3 feet (914 mm) from property lines; 3 feet (914 mm) from operable and nonoperable openings into the building and 10 feet (3048 mm) from mechanical air intakes except where the opening is located 3 feet (914 mm) above the air intake. Openings shall comply with Sections R303.5.2 and R303.6.


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## RLoureiro (Mar 3, 2021)

Thank you for the info on the distance from the window.

My only follow-on question is will it make a difference if the vent will be above the window by 3 feet?  Or does it just need to be 3 feet away?


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## north star (Mar 3, 2021)

*$ ~ $ ~ $*

*The vent shall be a minimum of 3 ft. away regardless of
being above or other........The wind can just as easily
affect the exhausts from any direction, back in to the
window.*

*$ ~ $ ~ $*


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## JCraver (Mar 4, 2021)

3 feet in any direction from the window (or any other opening back into the building) is the code minimum.  If you put the discharge 36-1/2 inches away, you're good to go.


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## RLoureiro (Mar 7, 2021)

Thanks to all for the feedback.  I will ensure that I am 36" away from the window.


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## Ed Cooke (Mar 11, 2021)

RLoureiro said:


> Hello,
> 
> I am planning to install a gas stovetop against an interior wall.  I am replacing a ceramic stovetop with a downdraft that goes under the slab, under the kitchen, and out to the exterior wall.  I plan on installing a vent-a-hood, and therefore cannot use the existing downdraft ventilation.  I therefore need to go over the kitchen (in the subfloor) and out to the exterior wall.  I will have room to install an 8" vent.
> 
> ...


The California Mechanical Code, or base UMC, in 519.5 states Type II shall be 10' from an openings into the building. The only way I see is out then up. Any thoughts on a new exterior chase on the side of your building? Good fortune.


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## Paul Sweet (Mar 12, 2021)

This is a residence in Texas, so I don't think the UMC applies.


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## Teeshot (Mar 15, 2021)

In CA, residential kitchen exhaust is considered Environment Air and follows the 3-foot requirement noted by JC & North.


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## Ed Cooke (Mar 16, 2021)

Teeshot said:


> In CA, residential kitchen exhaust is considered Environment Air and follows the 3-foot requirement noted by JC & North.


CMC definition of Environmental Air Duct and CMC section 502.2.1


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## Teeshot (Mar 16, 2021)

Yes, Ed, just clarifying that this is definitely not a Type II.


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## Ed Cooke (Mar 16, 2021)

Teeshot said:


> Yes, Ed, just clarifying that this is definitely not a Type II.


While it might be because it is definitely not a type I, the def. and code section from the CMC show it as an Environmental Air Duct for residential as noted by JC & North is correct. Therefore, not a type II. By reading those two sections it does make it very clear that the 3' rule can and should be an approved code installation.


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## Ed Cooke (Mar 16, 2021)

mtlogcabin said:


> How often is the window even opened?


Indeed, but the Pan Shovel picture is awesome!!!


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## mtlogcabin (Mar 16, 2021)

Guess again it is not a Panhead,  however it is modeled after the shovel head. it is an XR 750 motor


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## Ed Cooke (Mar 16, 2021)

mtlogcabin said:


> Guess again it is not a Panhead,  however it is modeled after the shovel head. it is an XR 750 motor
> View attachment 7599


The photo of the engine surely loos like a pan bottom and shovel heads. Built several of these to 96" back in the day. Well, not the 1st time I goofed!!


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