I know some people do and dont have an OAK and I have seen lots of reasons why to have one, but I havent really found any reasons or cons to having an OAK. So if you guys could, please tell me reasons why you shouldnt get an OAK installed? Sorry if this has been asked before or if its a dumb question.
Cons to having an O.A.K.
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boisblancboy said:
I'm not really for or against having an OAK - however there do appear to be some with rather passionate positions on both sides. Since you asked for the arguments against the OAK let me tell you why I decided against one (at least for the time being). Background to this is that I had thought I would install one with my new stove since I was in the middle of doing work anyway etc... I figured it couldn't hurt so I posted a thread that opened up a lively discussion.
Reasons I decided against adding an OAK:
1) There really doesn't appear to be any objective evidence that universally they improve the function of a stove in any way. This is not to say they can't help in some cases, however this IS saying there is no guarantee that adding one is going to help anything in all situations.
1a) There are several reasonable arguments and possible evidence that in some installs/situations having an OAK can actually make the stove performance worse. The situations basically are related to where the OAK input (outside the home) is and the wind direction, strength, etc.
2) There is a cost to adding the OAK
2a) Waiting to add it later does not materially increase this cost
3) Adding the OAK does damage to my house that is not easy to reverse
3a) Adding it later is not all that difficult and the install is no different
4) The OAK is not mandated by code for my install - which apparently may be the main reason that virtually every manufacturer has a kit or at least the capability to install one; i.e. if you don't you can sell to those states/regions/mobile homes that require them by code.
So the bottom line is that although there could be a benefit to having one it is very unclear what that benefit is unless it is solving a known problem that can't be solved another way. If I encounter that the cost of adding it is no more than now so I can do it. The benefit to having it in cases where the stove performs well without one is not as clear as it may seem - there are many folks who swear by them but no lab based evidence that they really improve efficiency or performance of the stove - if there is I'd love for someone to pipe in and correct me!
Risk of having a draft issue due to a wind direction change was too great for my comfort - I can't pull air from under my house (which seems the ideal place to pull it from as to be wind direction agnostic) so I'd have to be getting it from one side of my house and eventually it would be on the down-wind side which would be the low pressure side of the house and I don't know that I would like that on a weak draft moment.
Now, I have wondered if it might be worth it to attach the OAK and have it pull air from my basement as a way of burning cold basement air and forcing warmer air down there and thus try to heat the basement but from what I've also read the amount of air burned by a stove is so small it probably wouldn't help me a bit.
There are some situations I will really consider an OAK - basement stove in a tight house is one of them. Most of the cons stem from the info on woodheat.org.
That said, there are HUNDREDS of posts on here covering the pros and cons - run a search and give them a read.
That said, there are HUNDREDS of posts on here covering the pros and cons - run a search and give them a read.
Built my house five years ago and it very "tight". Installed an OAK five months ago in preparation for the new wood stove. New stove is a pedestal model and the oak feeds outside air under the pedestal. OAK would have been difficult to install this way after the stove is in place. Outside air intake for the OAK is 8' above ground level and located under a second story deck at the rear of the house. Air intake is subject to much air turbulence from all directions except easterly. Cost of installation was about $26 (I already had most of the needed materials). If I had to purchase all new materials I imagine it would have cost about $50.
I have no pre OAK and post OAK comparisons so I am unable to determine benefits of the OAK. However, I can say this: I am very happy with the OAK and can notice no adverse effects to having it. Fire starts very quickly and have not yet had to use more than one match in lighting. My respiratory system is sensitive to irritants and have had no adverse effects to having the wood stove. Neither I nor others can smell or feel (cold air drafts) any evidence of the wood stove in operation. Smoke alarm, carbon monoxide and carbon dioxide detectors have not yet reacted to the burning wood stove.
Except for the cost, the entire wood stove installation, including OAK, has been all positive and no negative. There was a whole lot of work involved in the entire project and I did it all myself (with friends) but that was part of the positive. I enjoy hard work, especially when the results are so bencficial and the job is well done.
Hope my experiences help some.
John_M
I have no pre OAK and post OAK comparisons so I am unable to determine benefits of the OAK. However, I can say this: I am very happy with the OAK and can notice no adverse effects to having it. Fire starts very quickly and have not yet had to use more than one match in lighting. My respiratory system is sensitive to irritants and have had no adverse effects to having the wood stove. Neither I nor others can smell or feel (cold air drafts) any evidence of the wood stove in operation. Smoke alarm, carbon monoxide and carbon dioxide detectors have not yet reacted to the burning wood stove.
Except for the cost, the entire wood stove installation, including OAK, has been all positive and no negative. There was a whole lot of work involved in the entire project and I did it all myself (with friends) but that was part of the positive. I enjoy hard work, especially when the results are so bencficial and the job is well done.
Hope my experiences help some.
John_M
Biggest reason for oak is to supply sufficient combustion air With out cracking a window open. In some cases also eliminates cold air draft along floor.
In one home I had ( not particularly tight) the floor draft of cold air was fairly intense. Enough so that sitting in a chair with feet on floor became quite uncomfortable even though the room was in the high 70's temp wise.
In some cases, especially if the place is sealed up pretty tight, it is wise to insall a general purpose OAK. Not just a dedicated one, this then supplies air for any non sealed appliance ( dryer, furnace, gas hot water heater, kitchen or other exhaust fans) eliminate neg. pressure in home, which in the case of the wood burning appliance can lead to a back draft at start up.
There are some kits for this available in which the in coming air is filtered and temperature modified passively. In fact I just caught the tail end of an installation of one on one the home rehab shows a few days ago. It is not difficult to construct your own at a mimimal cost.
In one home I had ( not particularly tight) the floor draft of cold air was fairly intense. Enough so that sitting in a chair with feet on floor became quite uncomfortable even though the room was in the high 70's temp wise.
In some cases, especially if the place is sealed up pretty tight, it is wise to insall a general purpose OAK. Not just a dedicated one, this then supplies air for any non sealed appliance ( dryer, furnace, gas hot water heater, kitchen or other exhaust fans) eliminate neg. pressure in home, which in the case of the wood burning appliance can lead to a back draft at start up.
There are some kits for this available in which the in coming air is filtered and temperature modified passively. In fact I just caught the tail end of an installation of one on one the home rehab shows a few days ago. It is not difficult to construct your own at a mimimal cost.
I think everything you need to know has been covered in this thread:
https://www.hearth.com/talk/threads/2496/
https://www.hearth.com/talk/threads/2496/
blades said:
Ok... I have wanted to toss this in somewhere on the whole OAK non-OAK debate to hear folk's reactions for a while and I suppose this is the current thread that is alive so here it is.
On the subject of "cold drafts" to the stove and the OAK solving this. I'm actually rather puzzled on this point. Mind you I have never had an OAK. I do, however have a draft in my house which is particularly strong around the stove when it is running. However - I am confident that it would not change significantly if I were to install an OAK since the heat of the stove is generating this draft. I can demonstrate that strong convection currents are being created by the stove (hanging paper around the room and watch the direction and intensity that they flutter), and since the air is clearly rising from the stove and leaving that area, air must be headed toward the stove from somewhere - obviously low and presumably cooler/cold air. So a hot stove is going to have drafts headed toward it one way or another right?
So the next question then is does the OAK change the temperature of the cold air returns? It would seem from a pure logic standpoint that this would be a function of where the air is coming from and if it changes - the presumption then being that without the OAK the return air has more outside (colder) air in it headed to the stove. Thus the "cold draft" issue really is only likely to change in a leaky house that is feeding cold air into the draft more than a "tight" house that doesn't feed cold air into the house since if your house is 'tight' then no cold air can get in to lower the temp of these drafts.
So - if you have to crack open a window to run your stove, you are going to have cold air headed in from that open window and obviously you are going to get cold - perhaps you need an OAK. If you don't need a window cracked open to run your stove because your house has enough leaks in it but you have a cold draft I suspect you are better off fixing all the leaks you can rather than adding another one pointed at the stove. Adding the OAK isn't going to fix those leaks - you will still lose heat through them and have cold walls/halls etc - IF you succeed in fixing those leaks well enough that you now have to leave a window cracked to run your stove, then see original statement and consider the OAK. Make sense?
To me the biggest issue is indoor air quality. I believe that NOT having an OAK improves your indoor air quality for the simple fact that the OAK prevents fresh air exchange to the air in your house that you actually breath. The other issue is the research which demonstrates OAKs are ineffective. Again all of this has been discussed to death in the thread I linked to above...
On that particular home, this was a inexpensive fireplace insert ( early 80's). The orginal fire place was a prefab with a 13" dia. flue. That thing, in its original state, created a wind tunnel which would suck every bit of heat out of the whole house, but it looked real pretty. The room it was in was a porch off the back of the attached garage. enclosed at a later date with a 6 panel bay window and a 8 ft sliding glass doors to the outside( prior to our purchase). To say that particular room was a thermal heatsink is an understatement ( no insulation ).
Exactly.
And just to clarify, a modern woodstove uses very little air, we are not talking about a stiff breeze here. Most people do not understand that, for example, a natural gas furnace uses MUCH MORE air than a woodstove, and yet hardly any natural gas furnaces use an outside air kit, why do you think that is?? How many people do you know talking about the need to get an outside air kit for their natural gas furnace?
This thread is about the negatives. The only negative that I have found is that I can't stuff a glove in the intake to stop a runaway stove. The OAK tube which feeds the intake system (for pook, all air primary and secondary) prevents me from plugging that hole in an emergency.
SLow1's post almost nailed one of the big positives with the cold draft being a warmer draft. The thing I think you missed was that with a non-oak house you are pulling cold outside air into the "return" air whether you think your house is leaky or not. That combustion air has to come in through leaks and all houses have them.
No harm can come from an OAK, only good things or nothing. The woodheat article has long been deemed bunk. I don't buy the air quality thing either, if you want an uncontrolled air leak for air quality then open a window. If you value the exchange of inside air with outside air then invest in a proper HRV system.
Good point about the gas furnaces. All of the new construction and retro installations that I've seen lately do include outdoor intakes. Water heaters and furnaces. Not sure if the code changed or what.
SLow1's post almost nailed one of the big positives with the cold draft being a warmer draft. The thing I think you missed was that with a non-oak house you are pulling cold outside air into the "return" air whether you think your house is leaky or not. That combustion air has to come in through leaks and all houses have them.
No harm can come from an OAK, only good things or nothing. The woodheat article has long been deemed bunk. I don't buy the air quality thing either, if you want an uncontrolled air leak for air quality then open a window. If you value the exchange of inside air with outside air then invest in a proper HRV system.
Good point about the gas furnaces. All of the new construction and retro installations that I've seen lately do include outdoor intakes. Water heaters and furnaces. Not sure if the code changed or what.
A possible/probable negative: Assume a house with a tight exterior skin. Without an OAK or a slightly open nearby window, all interior air used by the stove will be replaced by outside air "sucked" through exhaust vents at kitchen stoves, in bathrooms, fireplace chimneys, etc. My intuition tells me this movement of very large amounts of cold outside air through these few large openings will be noticeable and annoying.
My house has two ceiling fans which, during the burning season, are kept on a low setting blowing air up to help convection disperse the large "lake" of hot air which would normally be created at the ceiling. There are no (to me) noticeable cold air drafts from this mechanical movement of air.
Most persons reading this thread have probably already read the interesting and well written article at woodheat.org which argues that an OAK has very few, if any beneficial effects. An equally interesting and well written article at the chimneysweep.com argues in favor of the many beneficial effects of an OAK. Many agree with the points made in the woodheat.org article. Many others agree with the points made in thechimneysweep.com article. Having an OAK made more sense to me than not having one so I installed it.
A person who is really interested will read both articles and decide for himself/herself the pros and cons of an OAK. I believe the correct links have already been posted in previous hearth.com discussions of this issue.
My Weil-McLain "Ultra" PhD propane boiler came equipped with a 3" OAK which must be installed for proper combustion.
John_M
My house has two ceiling fans which, during the burning season, are kept on a low setting blowing air up to help convection disperse the large "lake" of hot air which would normally be created at the ceiling. There are no (to me) noticeable cold air drafts from this mechanical movement of air.
Most persons reading this thread have probably already read the interesting and well written article at woodheat.org which argues that an OAK has very few, if any beneficial effects. An equally interesting and well written article at the chimneysweep.com argues in favor of the many beneficial effects of an OAK. Many agree with the points made in the woodheat.org article. Many others agree with the points made in thechimneysweep.com article. Having an OAK made more sense to me than not having one so I installed it.
A person who is really interested will read both articles and decide for himself/herself the pros and cons of an OAK. I believe the correct links have already been posted in previous hearth.com discussions of this issue.
My Weil-McLain "Ultra" PhD propane boiler came equipped with a 3" OAK which must be installed for proper combustion.
John_M
I remember one member having problem, maybe not a huge one, but the AOK intake pipe was condensing & freezing and when stove not used, letting cold air into home.
The latter should not be a problem for a 24/7 burner.
It still amazes me the amount of ppl that think lack of OAK causes a severe draft in the home. Once up to temp and the air shut back, its not taking that much air in at that point.
I bet a ceiling fan would cause more of a draft than the stove. Those that don't have them, and have no issues, simply don't need them.
Those that have them, either need them or feel better having an extra add on. Everyone has their opinion. To say one works for all houses & situations is the bunk.
The latter should not be a problem for a 24/7 burner.
It still amazes me the amount of ppl that think lack of OAK causes a severe draft in the home. Once up to temp and the air shut back, its not taking that much air in at that point.
I bet a ceiling fan would cause more of a draft than the stove. Those that don't have them, and have no issues, simply don't need them.
Those that have them, either need them or feel better having an extra add on. Everyone has their opinion. To say one works for all houses & situations is the bunk.
Supposedly there was a wood heat conference where Gulland showed a house that actually did have the OAK issue with negative pressure due to winds. Essentially, you saw the stove die out, as the wind was blowing in the opposite direction the oak was pulling, then when the wind shifted back, the stove backdrafted pretty violently. The backdraft occurred inside the stove, and not the pipe, which, in a very extreme situation, could cause the glass to shatter.
That being said, it's probably best to not be running your stove in hurricane conditions anyway due to the high wind's effects on your chimney.
An OAK is always better, and this is true in both a leaky and a tight house. If you're heating with wood, you do not want cold drafts coming in the house. The stove does pull a large amount of air, and that air is going to come in through leaks in the house. The air moved via convection(as mentioned earlier in the thread) is not the same as cold air being pulled from outside. This is the difference between 60 degree indoor air lingering along the floor and 15 degree air from outside being pulled in through cracks and leaks.
That being said, it's probably best to not be running your stove in hurricane conditions anyway due to the high wind's effects on your chimney.
An OAK is always better, and this is true in both a leaky and a tight house. If you're heating with wood, you do not want cold drafts coming in the house. The stove does pull a large amount of air, and that air is going to come in through leaks in the house. The air moved via convection(as mentioned earlier in the thread) is not the same as cold air being pulled from outside. This is the difference between 60 degree indoor air lingering along the floor and 15 degree air from outside being pulled in through cracks and leaks.
I have a leaky two-story house, with only one stairwell to the upstairs. It has a door at the bottom. Whether that door is opened or closed for a few minutes (or even seconds) probably has more effect on the draftiness and pressure gradient of the house than an OAK could even over a period of a few hours. In the overall pressure picture for most houses, as far as cold air leaks, I would think an OAK is less than a drop in the bucket.
karri0n said:
Sorry bro, I ain't buying that one. I saw firsthand the size of the space that when the air leaver is cut all the way back. Its not even the size of a dime, maybe a 1/2 a dime at best.. How much air is that going to pull out of the home, & hence back into the home? That IMO is not a lot. Almost negligible.
Hogwildz said:
Wood stoves use about 10-25 cfm which doesn't seem like a lot but over the long run it may pile up.
I don't know how much air a stove uses but I am certain that the dime sized hole that remains when you cut down the primary air to zero is not telling you the whole story, bro. On a non-cat stove, that primary air slider only controls the primary air. The secondary air system is not controllable and is rolling full throttle through all those holes. I would imagine that a cat stove doesn't move as much air. The minimum bathroom fan runs 50 CFM.
20 CFM is what my old Century Stove used (I measured it with a blower door on a calm day). I do this work for a living so I know I did it right. Anyhow, I generally see more houses with air quality issues from being too tight and the little evacuation of 10-40 cfm per minute shouldn't scare anyone especially since it brings fresh air in from the outside helps keep the humans inside healthy.
Sorry, 20 CFM after secondary burning for about 45 minutes throttled about mid-way. On low/shut-down I suspect it would hit around 10-15 CFM.
Bottom line as far as I am concerned...............
When the settlers built their uninsulated, far from tight homes with regular ol open fireplaces.
They survived by that very inefficient fireplace. And sure they had worse drafts through those places than anyone could imagine.
I know my stove & my home. No draft that I feel a damning chill from.
With how houses are built today, unless you built it yourself, it may be fairly tight, but I doubt its as tight as you may think.
Unless you personally caulked all four sides of every stud bay to the sheathing & then even the seams in the sheathing. Walls, ceilings etc.
I actually did that in my addition. I highly doubt many builders go that extra mile. No OAK needed here.
I believe the question was what the cons were. But as usual, the debate teams are out and just have to force their opinion into the light.
One last con of an OAK, especially with that gawdawful looking flex piping. Makes it look like a gawdamn dryer. LMMFAO, now thats something to be adorned and proud of.
Go on with your debate, I find these same debates year after year very tiring. Knock yourselves out.
When the settlers built their uninsulated, far from tight homes with regular ol open fireplaces.
They survived by that very inefficient fireplace. And sure they had worse drafts through those places than anyone could imagine.
I know my stove & my home. No draft that I feel a damning chill from.
With how houses are built today, unless you built it yourself, it may be fairly tight, but I doubt its as tight as you may think.
Unless you personally caulked all four sides of every stud bay to the sheathing & then even the seams in the sheathing. Walls, ceilings etc.
I actually did that in my addition. I highly doubt many builders go that extra mile. No OAK needed here.
I believe the question was what the cons were. But as usual, the debate teams are out and just have to force their opinion into the light.
One last con of an OAK, especially with that gawdawful looking flex piping. Makes it look like a gawdamn dryer. LMMFAO, now thats something to be adorned and proud of.
Go on with your debate, I find these same debates year after year very tiring. Knock yourselves out.
Geez hog, for a guy that hates these debates you sure do post a lot in them. Stirring the pot and generating even more debate. Nobody is forcing anybody to do an OAK, we all know that they aren't required in every house. I hate the ugly dryer piping too, would have rather used hard pipe but couldn't get the bend radius. I apologize for the forum that you were so offended that you felt the need to repeatedly post in this thread. We'll start a new thread about brown stoves for you!
C02Neutral said:
That's exactly how I feel. The only counter argument so far is basically, "well OK, but if you want ventilation you can install an expensive (broken link removed)". That's fine with me, in that case go ahead and install both an OAK and an expensive air exchanger for your house (complete with constant power drain requirements and higher electric bills). While I'm fine with this idea if that's what you want to do, I'd personally rather just let the stove be my "free" air exchanger. I think this topic has been beaten to death, but I just want to emphasize that if you do use an OAK you should definitely also be using an air exchanger in your home.
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