Outside Air Kit - Oak - My research after investigating

[adam6979]

So we had a pretty good thread going and it got closed. I was actually looking at adding an OAK to my two stoves. I have done a significant amount of research and this article best describes the flawed logic with OAK's. I will stay with drawing the inside air....

(OLD THREAD: https://www.hearth.com/talk/threads/reasons-for-an-oak.137260/page-3)

Helpful Article: http://www.woodheat.org/the-outdoor-air-myth-exposed.html

 

[adam6979]

This was my favorite part: "The supposed benefits of outdoor air are not supported by research results."

 

[joed2323]

Drill a hole and be done with it It is nonsense why you are against another small hole! The benefits far outweigh the bad...

Getrdone

 

[Wilbur Feral]

1) That article has been cited before, on this forum.
2) It deals with woodstoves and fireplaces, not pellet stoves. You might notice that neither wood stoves nor fireplaces have combustion blowers that actively pump air out of a home.
3) Nothing in the article is referenced. Nothing...

You can believe whatever you want - I've given up trying to help those who are beyond it.

 

[fmsm]

Why would you want to burn heated air and replace it with cold outside air in your house?

 

[acammer]

Yea, this is dealing with passive systems with draft based exhaust. A pellet stove is a different animal.

 

[woodmakesheat]

It's not even required to drill a second hole, just widen the exhaust hole a little & either modify the thimble or buy one that's already modified to allow the OAK to feed through the common opening.
. I modified my thimble, but one can purchase a thimble that has the OAK

 

[alternativeheat]

Pellet stoves are different than wood stoves or coal stoves. Pellet stoves force air through the combustion chamber and up the vent. Air taken from your living space with no OAK. I've burned all three in this house and the draft situation in the house was never so pronounced as when I installed the pellet stove. I mean every single known draft in the house intensified maybe 3 fold. That is three times the cold air replacing warm through any hole it can get in through and it was honestly felt throughout the house in the form of what can only be called wind or a breeze.. This winter I put in the OAK and that phenomenon has returned to normal. You certainly can do as you please it's your house but I am here to tell you that OAK with a pellet stove makes a difference in My House where it was unneeded with either a wood or a coal stove..

Your stove is basically taking about ( speaking rough terms here) a block of heated air from your house roughly the size of a good sized closet every single minute it's operating. With in an hour depending on house size, it's cleaned your house out. And you think this is better than taking air from outside that is free ?

Some super tight houses require OAK and some stove manufacturers specify OAK on installation. There is a reason for this. Pellet stoves mechanically remove air from your breathing location.

 

[bogieb]

One stove I HAVE to have an OAK to make the clearance to windows legal. The other stove, I added the OAK after running for a month or so without one. Much prefer with the OAK. Plenty of people don't use them and are good with that. Plenty of people have put in "significant" research before putting in OAKs. Some people have found that what "experts" tell you to do (or not to do), does not work well in their particular case.

Do what you want to your place, makes absolutely no difference to mine.

 

[TimfromMA]

Not using OAK is the equivalent of cutting a 3 or 4 inch hole in your wall and putting a fan in it blowing out.

 

[F4jock]

With my Harman insert I insulated around the surround and opened the old fireplace rear cleanout door that opens into the garage. I then taped a six-inch ribbon on top of the frame hanging down into the opening. When the stove is firing the ribbon is sucked into the hole almost horizontaly. To me that represents a heck of a lot of room air that would have been used for combustion and thus would have had to have been replaced from outside.

 

[elevenMracing]

I agree with what alternativeheat said above. I recently switched from an lp furnace in the basement that used room air for combustion to a pellet furnace in the basement with an OAK. Ive noticed a large reduction in the amount of cold air drafting in through known leaky windows in the basement. I've had thoughts of drilling a hole through the interior door leading to the basememt and hooking up my manometer to it and running each furnace to see if there was a measurable difference.

 

[DBCOOPER]

One stove I HAVE to have an OAK to make the clearance to windows legal.

So Adam, why do you think an OAK would be required to reduce the exhaust clearance to a window? Perhaps the negative pressure inside the house could draw in the exhaust somewhere around the window/frame?

 

[St_Earl]

yes. anytime i get a thread locked on a message board, i take it to mean i should start another on the exact same topic as soon as possible.

you could spend a solid week reading the search results here for OAK.

 

[bags]

No scientific research needed. It's common sense. Quit worrying about researching about what he said,,, she said on the OAKS and spend some time looking into positive and negative air within a home. Also look into combustion air for say gas fired appliances and how they compete for air with bath fans, exhaust hoods and the like. Flues will not draft properly if they are being robbed of air by appliances, furnaces, etc; There are scientific studies on this stuff. You are just looking at the wrong ones. Get an energy audit and hook up a blower door test to your house and see how much leaky air that bad boy finds for you. You'll be surprised. Your stoves are finding them too.

You need to understand how air moves and apply that to pellet stoves. I'll make it simple in a simple scenario. IF you have a 200 CFM blower on your stove putting out 200 CFMs of hot air but also leave a bath fan on that pulls out 150 CFMs then you are only gaining 50 CFMs of warm air. Keeping this in simple math terms here. Why do these newer high efficiency gas furnaces need outside air? So they can be efficient and not steal air from inside. A pellet stove operates much the same but only burns a different fuel. Pellets instead of gas. I've seen plenty of those furnaces pulling air from the basements because some installer took a short cut.

200 warm CFM input - 150 CFMs exhausted leaves = 50 CFM of warm air for you. With this you are burning 40 lbs. of pellets and only benefiting from 10 lbs. Trying to keep this very simple to avoid arguments and there are other factors that can be considered. Technically, each occupant in the home puts off BTU's but like I said, simple. On the flip side to quash that argument windows lose and gain too. It can get very complex but it can all be figured out in calculations.

So the bath fan stole 150 CFMs of your warm air. A pellet stove is in a sense a bath fan exhausting to a degree. It blows AIR out. Where is it getting the air it is exhausting? It's stealing it from inside your home all while pulling in cold outside air from leaks, bad weather stripping, can light housings, etc;

Lucky for us all this is still a free country and we as individuals can do what we chose to do. If you don't want an OAK and think they are a waste of time then great. I'm all for it. We can all just agree to disagree. I'm not paying for your pellets and you are not paying for mine. It's all good!

 

[Skier76]

My research indidates a "heated" (pun intended) debate with no agreement in sight.

 

[F4jock]

My research indidates a "heated" (pun intended) debate with no agreement in sight.

I'm having a hard time understanding how anyonone can argue with elementary physics. Nature abhors a vacuum. When you draw combustion air from a room and send it up the stack it MUST be replaced else the room will eventually implode. Since there is a limited volume of air in the room removing some of that air creates a very slight vacuum. Air will move into that room to fill that vaccum following the path of least resistance. This path may be from another room but ultimately the slight negative pressure the stove creates in the house MUST be equalized with an influx of air and the only place that equalizing air can ultimately come from is, wait for it, the outside. The colder outside. Now, if one takes the combustion air from the outside, as with an OAK, and returns it there, no negative pressure is created in the house and thus infiltration of cold outside air is not exacerbated. You will still have exchange of air through badly sealed windows, doors etc. but it won't be sucked into house by removal of air from within. You can't argue the physics of this, unless maybe you want to get into quantum mechanics.

 

[bags]

That attached article isn't worth the paper it's written on IMO for various reasons. It is merely "someone else's" opinion. They talk a mean game but have no facts to back their statements either. Some research and things were stated but not cited, referenced, nor backed with proof and facts. When was it even written? Some statements are valid regarding air flow and such but nowhere is this author talking about the outside air regarding pellet stoves. I will agree many building codes are very generalized and many municipalities just follow suit out of ease and to have something on the books that someone else had an opinion about or Larry the engineer in New York signed off on. Many situations are different and you can not always apply how it reads in the rule book so to speak. There are exceptions to everything. They are talking about wood stoves and fire places. Not a pellet stove which pulls and pushes air in an entirely different manner.

Anything that requires combustion air will get it from pulling the air from somewhere. The bigger need appliances and burners usually win too. To put that article in a nut shell, Yes, sure things will get and pull air from somewhere. They even showed pictures or drawings of it theoretically. Might have been a bit off on arrow placement. Maybe not. LOL! The main point is that an OAK reduces a pellet stove from pulling already heated inside air for combustion and replacing that lost warm air with leaky air from your homes envelope. I don't think you understand fully what some here are saying.

Just like in the article they found out the big fancy high CFM 1980's range hoods were stealing air. I feel the author's opinion is a bit dated and generalized. Many newer appliances have remedied their need to steal air. Examples are: Powered vented gas hot water heaters and furnaces supplying and exhausting their own air. Many range hoods are no longer direct vent that push air outside. Some appliances have to be vented outside or should be. Bath fans and dryer vents are two. I've seen where Jimmy Bob Billy has slung some hose to wherever on those as well. Attic spaces and basement floors seem to be a favorite.

This article is also not referring to pellet stoves in any way, shape, nor form. Pellet stoves do control their outside air intake. This author is talking about some free ranging wild hole in the wall. I just read this after my comment above. This article has no relevance for pellet stoves. Sorry to be the bearer of bad news.

 

[Don2222]

So we had a pretty good thread going and it got closed. I was actually looking at adding an OAK to my two stoves. I have done a significant amount of research and this article best describes the flawed logic with OAK's. I will stay with drawing the inside air....

(OLD THREAD: https://www.hearth.com/talk/threads/reasons-for-an-oak.137260/page-3)

Helpful Article: http://www.woodheat.org/the-outdoor-air-myth-exposed.html

1. Why put heated room air up the chimney with no OAK?

2. Why run cold damp air into the burnpot with an OAK?

Why not pull in outside air and heat it and dry it out then send it into the burn pot? ? ?

Answer is simple here!
Selkirk DT is a no brainier for me!

See my pics here
https://www.hearth.com/talk/threads...n-out-direct-or-top-vent.129497/#post-1743756

 

[3650]

if you have a tight house you probably wont notice a whole lot of difference, but if your curtains blow with the wind you will wonder why you did do it sooner. At least that was my experience. I have an uninsulated 100 yo splitfaced block house with single pane windows. I could figure out why my thermostat read 80* and I was freezing. I bought one of those window units for the back room and they are self contained and therefore use outside air. I couldn't believe how warm the back room was. Then it dawned on me it had outside air. I hooked up an oak using 3" rigid aluminum dryer vent and have never looked back. The difference was amazing. On the other hand my sister has the same stove as me and her house is tighter then a bed bug in a book crack. She has no oak and her house is hot on the lowest setting most of the time.

 

[bags]

Don,
Several OAKS do preheat the outside air first and that is better. Mine does. That said, I'd still rather have one pulling cold damp air in thru any OAK than sending my warm air out the stack. Humidity is usually down in the winter's cold air too but heating it is ideal.

3650,
All houses leak. Even the tight new ones sprayed with foam. Not a lot but they are losing heat somewhere. Otherwise you could heat it once in a great while and maintain the desired temps. Eventually, the heat would radiate out and or cold in. Some homes are worse than others and with your sister she is experiencing a lower rate of loss and her stove is pumping in more warm air than she's losing which is a good problem to have. My last place was an older drafty place and that's no fun.

 

[Zebby]

Yep - I have an OAK direct to the firebox.
The stove is actively pulling in a quantity of fresh air, using it in combustion, and actively pushing the hot expanded products of combustion and excess air out the vent.
Warm/moist room air is drawn through the heat exchanger, heated and pushed back into the room.
That's the way I like it.

OAK - just do it!

 

[F4jock]

Don,
Several OAKS do preheat the outside air first and that is better. Mine does. That said, I'd still rather have one pulling cold damp air in thru any OAK than sending my warm air out the stack. Humidity is usually down in the winter's cold air too but heating it is ideal.

There are two telling statements in the last paragraphs of the cited article on the myths of outside air. Essentially they state that the entire article is premised on largely passive air feed to a system whose draft is totally based on natural chimney draft, something that essentially does not exist with a pellet stove.

 

[F4jock]

if you have a tight house you probably wont notice a whole lot of difference, but if your curtains blow with the wind you will wonder why you did do it sooner. At least that was my experience. I have an uninsulated 100 yo splitfaced block house with single pane windows. I could figure out why my thermostat read 80* and I was freezing. I bought one of those window units for the back room and they are self contained and therefore use outside air. I couldn't believe how warm the back room was. Then it dawned on me it had outside air. I hooked up an oak using 3" rigid aluminum dryer vent and have never looked back. The difference was amazing. On the other hand my sister has the same stove as me and her house is tighter then a bed bug in a book crack. She has no oak and her house is hot on the lowest setting most of the time.

Combustion air has to come from somewhere to equalize pressure or the house would have imploded and your sister exploded.

 

[checkthisout]

The article is for wood stoves which use natural draft and are thus not equipped with a blower.

In that case, the article probably makes some accurate points but does not provide any references to any sources of information used to make the conclusions.

In a lot of cases sure, an OAK probably isn't that big of a deal because the stack effect that comes from heating the house (higher pressure generated by hot air rising the ceiling) is probably a larger loss than a draft generated by a wood-burning stove and may, as the author stated (without citing any sources) may actually cause problems during high winds.

In the case of a pellet stove, sure, some people probably have such leaky, poorly insulated houses that a closed loop combustion circuit won't make any noticeable difference. In other words there are bigger fish to fry before installing an OAK. However, installing the OAK certainly wouldn't hurt and would be the final step in the making the system as efficient as possible.

As others have stated, there is a reason high-efficiency Natural Gas appliances have closed combustion systems and also why pellet stove manufacturers can spec a lower exhaust-to-window clearance if an OAK is used.

If you don't believe an OAK helps out in terms to using less fuel to heat your particular building then explain why countless engineering studies have shown otherwise.

This is a fun discussion but lets keep it civil. Hearth.Com is one of the few internet forums I frequent where people don't flame each other, as frustrating as it can be when someone on the internet is wrong.....