# Location of makeup air



## digifabb (Nov 11, 2020)

Planning to place two inlets for makeup air for a 30" wolf stove and 1200 cfm vent hood.
Planning two makeup inlets on each side of the stove, through the outside wall at the back of the stove.
I can place it near the floor or 2/3 the stove height above the floor.
Any recommendations on this decision?
Would also like input on how to disperse the air as it enters the room.  Such as baffles, etc?

Thanks for any suggestions.


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## cda (Nov 11, 2020)

digifabb said:


> Planning to place two inlets for makeup air for a 30" wolf stove and 1200 cfm vent hood.
> Planning two makeup inlets on each side of the stove, through the outside wall at the back of the stove.
> I can place it near the floor or 2/3 the stove height above the floor.
> Any recommendations on this decision?
> ...




Welcome

Not into mechanical, but you are bringing in unconditioned air from the outside??

Which state are you in???


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## Keystone (Nov 12, 2020)

Are you trying to use the interior air for stove hood makeup air? Having makeup air alongside the stove from the interior air is no different then not having makeup air at all from your hood, both coming from the interior which defeats the intent of makeup air..  

The makeup air needs to be brought in from the exterior. Typically via a duct at exterior routed to the return side of the HVAC system triggered by a micro switch connected to the hood when in operation.   This is the most common method I see burn not the only method.


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## digifabb (Nov 12, 2020)

cda said:


> Welcome
> 
> Not into mechanical, but you are bringing in unconditioned air from the outside??
> 
> Which state are you in???





Keystone said:


> Are you trying to use the interior air for stove hood makeup air? Having makeup air alongside the stove from the interior air is no different then not having makeup air at all from your hood, both coming from the interior which defeats the intent of makeup air..
> 
> The makeup air needs to be brought in from the exterior. Typically via a duct at exterior routed to the return side of the HVAC system triggered by a micro switch connected to the hood when in operation.   This is the most common method I see burn not the only method.


Thanks for your reply

No, the makeup air is drawn through two ducts through the outside wall so the air is drawn directly.
Due to the geometry of the house we do  not favor using the return duct of the HVAC.
We live in coastal Washington State so temperatures are almost never below 20F.

I have the idea that having the makeup air near the bottom of the range the air will draft upward along both sides and the back of the stove, hopefully carrying away the smoke and fat.

I have seen other's installations in which they bring the makeup air into the house along the base boards near the range.


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## cda (Nov 12, 2020)

digifabb said:


> Thanks for your reply
> 
> No, the makeup air is drawn through two ducts through the outside wall so the air is drawn directly.
> Due to the geometry of the house we do  not favor using the return duct of the HVAC.
> ...




Not into make up air directly, 

Will there be a fan to pull air in, or just free flow?

When it does get to 32F, and you decide to cook with the vent a hood running, and how ever the make up air gets into the house, you will be bringing freezing air into the house, and the vent a hood will be sucking the heated air from the hvac out of the house.

Are you picking 1200 cfm because the city is telling you to? Or the stove supplier is telling you to???, or why???

I recently installed a gas range, and yes it does put out some heat. Had a small already installed vent a hood, and seems to work. Not into smells, since I do not cook smelly food, except garlic, so smell is not a big thing to me. 

How many sq ft is your house, one or two story house? how big is the kitchen sq ft, kind of open concept, or kind of room by itself??


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## digifabb (Nov 12, 2020)

cda said:


> Not into make up air directly,
> 
> Will there be a fan to pull air in, or just free flow?
> 
> ...


Good questions, thanks.
No fan, just drawn in by the vacuum created by the vent hood blower.

Yes, any vent hood will need to draw air into the house envelope.  What we don't want is to create a substantial vacuum in the house:  that will draw CO2 from any other gas heating inside the envelope such as a fireplace.  Worse, we do not want to pull the damp wet NW air through the walls due to mold that would like to grow, and any contaminates that may linger in the walls such as mold, dust, allergens, etc.  Furthermore, the house is a recent build and quite tight so without makeup air, we may not get much more than the current 600 cfm no matter how hard we blow.

It is an open kitchen so the space open to the kitchen is about 1500 sq. ft.  A long rectangle with the range at one end.  I believe we will lose less heat from the house if the cold outside air brought into the house is mostly immediately exhausted, being near the vent hood.  Of course, it has to sweep past the stove top.

We currently have a 600 cfm vent hood with a piddly rectangular duct and very noisy.  The house almost immediately fills with cooking odors and smoke so that we have to open doors and windows.  Wok and other frying, when done right creates lots of smoke and oil residues. 

After the makeup air is self installed, should we find it is uncomfortable in winter, we have the option of choking it as the vane in the duct can be adjusted to more or less air flow.


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## cda (Nov 12, 2020)

digifabb said:


> Good questions, thanks.
> No fan, just drawn in by the vacuum created by the vent hood blower.
> 
> Yes, any vent hood will need to draw air into the house envelope.  What we don't want is to create a substantial vacuum in the house:  that will draw CO2 from any other gas heating inside the envelope such as a fireplace.  Worse, we do not want to pull the damp wet NW air through the walls due to mold that would like to grow, and any contaminates that may linger in the walls such as mold, dust, allergens, etc.  Furthermore, the house is a recent build and quite tight so without makeup air, we may not get much more than the current 600 cfm no matter how hard we blow.
> ...




Ok being a house, not sure who to direct you to??

If you could find a home mechanical expert to advise you.

My vent a hood is ducted to the outside, with no flappers or anything to block air from coming in. So when it is cold, I can fell the cold air coming in from the outside.

Give  it a few days, and you will get some replies that can give you direction. 


""""I believe we will lose less heat from the house if the cold outside air brought into the house is mostly immediately exhausted,"""""

           Not sure if this will work in reality


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## cda (Nov 12, 2020)

https://www.amazon.com/Universal-Automatic-Make-Up-Damper-Pressure/dp/B00R8MQHW8
		





			https://www.broan-nutone.com/getmedia/15e4b5d5-1f83-4921-8880-1aba5becb0b5/Broan-make-up-air-damper-catalog.pdf


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## digifabb (Nov 12, 2020)

cda said:


> https://www.amazon.com/Universal-Automatic-Make-Up-Damper-Pressure/dp/B00R8MQHW8
> 
> 
> 
> ...


Thanks.

The Zephyr makeup air works on the same principle as the Broan.  Their website was helpful  though, thanks.

I had seen the air flow page you attached.  It had both positive and negative reviews as a method.

I agree, it is all a bit of a guess.  The worst that can happen is we don't like it and since I am doing the work myself, I can revert to putting it in the return air of the central heating.  Not too happy about two holes in the walls but even that can easily be patched to be imvisible.  No harm done.

Thank you all for your help.  I appreciate it.


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## ADAguy (Nov 12, 2020)

Hmmm? a cunumdrum remains; not pulling a permit are you?


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## Rick18071 (Nov 12, 2020)

ADAguy said:


> Hmmm? a cunumdrum remains; not pulling a permit are you?


We don't know if a permit is required where they live.  Wouldn't need one in most of PA for this.


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