# Outside air intake for interior wood stove..has any one done it??



## woodguy105 (Aug 17, 2008)

I've been burning wood for about 7 years. I 've got a Travis Industries LOPI Answer that I'm thinking of venting for outside combustion air (instead of sucking up the warm interior air). I know the manufacturer has the set up & specs for connecting the vent, but I'd like to hear from anyone using outside cumbustion air for an indoor wood stove pros & cons?

My stove has great draft w/ a straight pipe up through the ceiling. I'm just wondering if the stone cold ouside air will impact the efficiency even though it's supposed to be "prewarmed" within he unit before hiting the cumbusttion chamber.

Any thoughts or experiences.

FYI I love my LOPI Answer-one of three wood stoves that we have.
Thanks-


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## 046 (Aug 17, 2008)

been running outside air for combustion from day one. 

air comes in from bottom via ash dump chute. 

Insert is a JUCA that uses existing fire brick floor. I've got sliding vents to control use of interior air too. but those are closed down, with all combustion air coming from outside.


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## woodguy105 (Aug 17, 2008)

*outside air...*

Excellent. 

Must make a big difference not sucking the cold air into the house.


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## woodguy105 (Aug 17, 2008)

combustion that is ....


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## IdahoPanhandle (Aug 17, 2008)

Using outside air for combustion is the ONLY way to go.

Keeps cold air out, and heats what air you have inside the house.


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## HUSKYMAN (Aug 17, 2008)

How does this help? Does using the inside air create some kind of vacuum that makes your insulation and windows less effective or something?


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## woodguy105 (Aug 17, 2008)

TreeCo said:


> It seemed like such a good idea until it was tested.
> 
> http://woodheat.org/outdoorair/outdoorair.htm



interesting ...somehing to think about.


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## woodguy105 (Aug 17, 2008)

HUSKYMAN said:


> How does this help? Does using the inside air create some kind of vacuum that makes your insulation and windows less effective or something?



Seems to me that instead of causing " a vacum" of air up the chimney, use outside air directly connected to the stove inlet and keep the cold outside air from being sucked in through all of the nooks and crannies. 

Treeco's woodheat.org link looks at it a bit differently..


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## IdahoPanhandle (Aug 17, 2008)

It amazes me how many people misread that site  



woodguy105 said:


> Treeco's woodheat.org link looks at it a bit differently..



Simply because they are addressing a completely different issue.

That link only looks at smoke spillage into the house, due to pressure differences between the inside and outside. Regardless of what type of air intake you have, there WILL be a pressure difference, and spillage is always possible. Smoke will simply follow the path of least resistance. If the chimney is chocked down to the point of creating a good amount of resistance, then smoke will spill into the house when you open the door. Spillage is also possible thru the air intake. 

The fix is quite simple.  Open up the flu before opening the door!

All that link says is that drawing in outside air DOES NOT EFFECT SPILLAGE.
Nowhere does it say ANYTHING, about anything else.


The primary benefit of drawing air from outside air is to heat the inside air, and ONLY the inside air. When you suck air from the inside of the house, it has to be replenished somehow. This means that cold air from the outside is drawn into the house thru openings in the windows/doors/etc. With a sealed uint (drawing from the outside) you eliminate this problem.


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## Rookie1 (Aug 17, 2008)

This may be kinda stupid but when I added on to my house I put in a fireplace. On my masons advise I put in an outsie air intake system. Its all homemade and even though its not as efficient as wood stove I think it does help. You just have to remember to close it when fires out.


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## Wirenut2266 (Aug 17, 2008)

+1 What Panhandle said!


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## cityevader (Aug 17, 2008)

TreeCo said:


> It seemed like such a good idea until it was tested.
> 
> http://woodheat.org/outdoorair/outdoorair.htm



uhhh...tested?

All that "scientific mumbo jumbo" made me stop reading.....

My airtight stove has a 3 inch air intake on the back that simply sucked house air out the chimney pipe for several years. I grew tired of the wind coming from every outlet and wall switch and window. I smashed and clawed and pleaded my way throught he old masonry chimney until I had a hole big enough for a flex tube to the outside. Voila!! no more drafts from everything! Indoor temp dramatically improved. That's the only science i'll believe.


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## 046 (Aug 17, 2008)

generally this site has good info.. but their outside air example don't apply to all types of wood stoves. 

in general they are assuming one is using an air tight wood burning. which doesn't use large CFM of air. vs an open burn system which uses large volume of air. 

I've tested both ways on mine... don't know about anyone else, but outside combustion air works substantially better for me. 

my house is particularly tight. when outside air is closed off. fireplace has a hard time drawing enough air. a window has to be cracked. 

with all windows locked down for winter. my wood insert is one big heat exchanger. blower pulls air from host room. sends it through heat exchangers, coming out heated... nothing special going on..

got a smoke detector and carbon monoxide detector on the mantle to monitor spillage. 
how long smoke lingers next to heat exchanger before going up chimney, greatly effects transfer efficiency. this is controlled by careful adjustment of damper. 

again ... I'm referring specifically to my insert.... not anyone else's. 
been brain storming for several months now...on adding secondary burn to my insert. hoping to double efficiency. 



TreeCo said:


> http://woodheat.org/outdoorair/outdoorairmyth.htm


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## loknlod (Aug 18, 2008)

*+1 for outside air intake*

Yup, prior to getting our wood stove installed I printed the owners manual off the internet to get as much information as I could. My particular stove manufacturer recommended a fresh outside air intake for the stove so that is what I did. The person who sold me the stove and did the installation has been doing this for over 30 years, he also highly recommended that I used outside air. Mine is basically a dryer vent set up (flex tube from stove out to the vent cap on the side of the house.) Depending on your outside air temps, you may want to insulate that tube because it will radiate the cold.


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## Locoweed (Aug 18, 2008)

Going to the page http://woodheat.org/outdoorair/outdoorair.htm

The first link says

Excerpts from Fireplace Air Requirements, the CMHC study that shed light on the outdoor combustion air question.

Notice that it says fireplace air requirements. Clicking on the link you will find a executive summary with no mention of stoves.

Clicking on the second link takes you to the page http://woodheat.org/outdoorair/outdoorairmyth.htm

This page gives no reference to any studies, nor is it signed by anyone.. There is mention of stoves on this page.

I think this page is just someones opinion. I feel it is more likely to be applicable to fireplaces than wood stoves. Bluntly put, I think they are full of it concerning air tight wood stoves.


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## Tracker83 (Aug 18, 2008)

From the last sentance in the article:


woodheat.org said:


> In general, therefore, fireplaces that are vented by natural chimney draft should draw the air for combustion from the room in which they are located. *Where necessary the indoor air pressure should be controlled to minimize depressurization.*


A.K.A. you will need to add a device to the home to connect the inside air of the home to the outside air to ensure equalization of pressures. LOL! (but don't call said device an outdoor air intake.....)

This whole topic seems to be over-complicating something that is very simple science. The "natural draft" will cause "x" CFM of inside air to leave the home via the chiminey. To avoid turning the home into a vaccum that same x CFM of air must enter the home from the outside. In reality very few homes are built tight enough to hold much of a vaccum, so "x" CFM will enter the home via windows, doors, light fixtures, or any other envelope penetrations. So in reality the only issue at hand is if you control the intake of outside air via a physical device that allows you to direct that air to the wood-burning device, or you allow the home to natually "breathe" to receive the outside air. Either way, the same "x" CFM of outside air is entering the home.


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## woodguy105 (Aug 18, 2008)

It amazes me how many people misread that site ...


Quote:
Originally Posted by woodguy105 
Treeco's woodheat.org link looks at it a bit differently.. 

I'm interested in increasing efficiency, warmth and limiting cold drafts from outside air. A good chimney and correct use of a stove and spillage is not an issue ...so yes woodheat .org looks at it a bit differently.




Sounds like I've got another project, I'll vent to the outside and hopefully burn less and stay warmer!


Thanks for the input.


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## Crofter (Aug 18, 2008)

I think that article emphasizes some very specific situations where dedicated outside combustion air could possibly NOT be of benefit but it seems to be where the chimney is not producing adequate draught and the stove would be inclined to spill smoke into the room anyways. 
Outside combustion air will not cure every situation. There are still instances of a totally sealed house having problems if range, bathroom and dryer vents, and perhaps a non vented oil furnace all happen to operate simultaneously and create a vacuum inside the building. They also cite the vacuum created by extremely strong winds. In either case a wood stove would spill into the room. I would prefer to bring in the outside combustion air in the immediate vicinity of the stoves air intake. If the house is well sealed the stove wont suck in any more cold air than it needs. If the powered venting devices are still creating a vacuum that effects the stove then they need a heat exchanged venting system that provides balanced outside air intake and cures that problem.

That article has some strong anti establishment sentiment and starts out with the premise that the fire code rules are put in place just to create unnecessary irritation to people.


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## olyman (Aug 18, 2008)

think about it---any appliance that uses a fuel for heat--is drawing oxygen out of the air--some older people died in their houses years ago because they were airtight--and no oxygen being brought back into the house--these people didnt leave their houses for days on end---1/e winter------so thats why gas furnaces are required in most states to have a outside air intake---tell me why it would be any diff for a woodstove?????? it AINT---inspite of "scientific" people--no real world experience!!!!!! a "suction" being created in the house when the wood is burning, and it will pull air into any air leak in the house---better to bring it in next to the wood burner--and it will go into the burner only, unless you put it on the north side of the house right into the gale wind----intakes are supposed to be on the east or south side of the house--because of prevailing winds


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