Can an "Outside Air Kit" (OAK) simply NOT work after its installed?

[A M]

My friend installed the OAK today and I helped. It was added to the rear of a Drolet Myraid wood stove.

Because the 4' long and 5" wide insulation piece was too long, he cut it off and fit it to the rear of the stove, after making a hole through the wall to the outside and then screwed in the vent part.

We put foil tape around the end part that comes out of the rear hole opening, from the pieces of metal that came in the kit.

Neither of us want to pre-judge, but, nothing wants to burn inside the stove box after it was installed. Pieces of cedar, pieces of newly cut small pieces of maple tree cut pieces. The twigs will burn but will not ignite anything else. The firestarter and supercedar pieces still burn until they burn out, but nothing is causing anything larger to ignite for more than 2 minutes.

Is this just a coinsidence and bad wood ... has anyone ever heard of an OAK doing the opposite of what it is suppose to do?

Even with the door all the way open with me monitoring it constantly for several minutes, nothing will burn more than 2 minutes and then burn itself out, leaving just a few ends of wood with a little bit of red on them.

My friend had never installed an OAK before and I had never helped to install one, so if you can share your thoughts on this, I will be grateful.

P. S. Does it matter if the insulation part that goes out of the house IS NOT perfectly propped in a LEVEL line? Meaning, after it is attached to the back of the stove, part of it flops to the floor and then the remainder of it goes up from the floor and then up a foot (?) or so through the side hole of the wall and then it is outside. The air can still get through INTO the stove however the insulation is sitting, right???

 

[BrotherBart]

If it ain't burning with the door cracked open a bit, the OAK ain't the problem.

 

[A M]

If it ain't burning with the door cracked open a bit, the OAK ain't the problem.

... So, if I am giving it MORE AIR manually by opening the stove door all the way and the wood still IS NOT burning, it has nothing to do with the OAK, you're saying? I took another look at the insulation after I posted this. It is not on the floor, but it is not going out toward the outside on a LEVELED stance. In fact it is going UP from where it is connected in the back of stove.

Does this make ANY difference in how it is taking in all of that outside air? My friend said the position of the insulation pipe should make NO DIFFERENCE whatsoever, as the outside air will travel into it regardless of its position to the outside of the house.

Agree?

 

[sticks]

any class I have been to outside air talked more about what did not work. One topic was about location. If it is not on the windward side of the house you may have negatie pressure on that part of house.

 

[A M]

any class I have been to outside air talked more about what did not work. One topic was about location. If it is not on the windward side of the house you may have negatie pressure on that part of house.

OK, I guess this is a possibility. I've heard of negative air pressure. I'm fairly certain this is the "wind" side, but not positive. Thanks for your opinion on this.

 

[Sprinter]

This site: http://www.woodheat.org/the-outdoor-air-myth-exposed.html explains some situations where an OAK could be a problem.

However, I think these kind of problems are fairly rare, and typically, OAK is a very good idea. I know it works very well for me, and, I'd guess, for most.

A draft problem like this needs troubleshooting, but I wouldn't blame the OAK offhand.

 

[DougA]

Wouldn't it be very easy to take the adapter attached to the stove off and try a few loads of the same wood without the OAK? I just installed one on my stove last week and it works great but I made sure that I can access it just in case I needed to remove it for any reason.
All an OAK does is to bring cooler outside air into the stove for combustion instead of using already heated air from the house. As long as your run is not too long or restricted in any way, it should not cause a problem. Remember to ensure that the outside vent is rodent proof otherwise it will make an excellent place for mice to make a home.

 

[iluvjazznjava]

My OAK on my Jotul F55 works great and that's with a run of pipe over 30 feet long. Yours is much shorter, so I doubt you have a problem with an excessively long run ... but I'm at a loss what your real issue may be.

 

[matt1@]

I think BrotherBart has an excellent point. If nothing burns even with the door open, air going into the fire isn't the issue. Chances are you have a draft problem, maybe a baffle is out of place or a clog in the chimney. I'd check that next if I were you.

 

[A M]

Thanks for these newest (4) replies. Yes, Bart has a point. This morning I started anew ... I emptied the box of the large (partially) burnt pieces of wood. The "twigs" were underneath which I thought had already been burnt from last night. I did not clean out the rest of the ash that I had mostly cleaned out yesterday afternoon, after the new OAK had been installed.

So, ... since I have left over pieces of cedar left over from a window project my friend had recently done for me, I got out my new Ryobi sawzall and cut a four foot length of one inch cedar into four pieces. Then I used a Fire starter under the twigs and made a teepee with the cedar pieces. The fire started ... and it did not go out within ten minutes as it did yesterday!

This finally happened around 11AM and it has been going since then. At one point it hit 500 degrees but it has mainly stayed in the 325 to 400 range. We're in the low 50s today, so it is not cold, per say. However, it is easier for me to keep the fire going on a "low" basis (but not as to effect the build up of creosote, if I keep it under 200, which I never wish to), so that in the late afternoon / early evening, I begin to put in the larger pieces of wood to keep the house warm until I hit the hay.

Regarding the OAK installation, ... my friend and I did not want to jump to conclusions initially, especially myself, as the "kit" and piping cost me about $130.00 total ... so, that's why I thought I'd take out that partially burnt up wood and try again. BTW, the stove box has been so nice and hot today after that that I re-burned those pieces. My initial concern, - if it was the fault of the OAK install - was that the position of the piping, well, the best way I can describe the direction of it without being able to draw it here, would be to refer you to the shape of the "Nike" icon. Once it comes out of the back of the black metal piece we attached, it just goes upward and not straight across on a level 'til it comes out through the OSB board and then ends at the screened part on the outside of the house. I was concerned because while I totally get that it is simply suppose to allow fresh 'outside' air INTO the house, I thought that due to it being at an angle, perhaps the air wouldn't get all the way INTO the back of the stove?

Anyway, ... once again, because I am now getting good results ... it had to have been the wood. But, I do not understand why the good "cedar" did not burn, so, that is what threw us. I can understand bad/wet wood but dry, clean, cedar pieces refusing to stay lit, too? Just don't get that.

As far as telling you if I can see or realize a distinct difference - in a positive way - I will have to start a few more fires before I am convinced that I am getting quicker start-ups or less smell of the wood in the house.

That article from (broken link removed) about the OAK ... while it was interesting and somewhat technical ... I am not convinced that OAKs are unnecessary because it is far too early for me to say from my own personal experience ... and that is only from one source, anyway. Sprinter was correct when he mentioned that the issues in the article are most likely fairly rare. Noteworthy to add is that I just had my chimney extended by three feet two weeks ago, so, this factored into our surprise that a fire did not want to get going right away the OAK was installed yesterday.

I bought a package of kiln dried "kindling" today and will use this to start my next "cold" fire. I will see how quickly it heats up, whether it goes out at all, etc. With a working extended chimney, a working OAK, and hopefully the right wood, ... there is no reason why I should not be having good, hot fires this winter (instead of paying for electric heat to a heating Cooperative in my area). Now, that in itself is worth injecting a beautiful smile right here:

Anyway, ... I appreciate the various opinions I have gotten from you all. Thank you.

 

[clr8ter]

Pieces of cedar, pieces of newly cut small pieces of maple tree cut pieces. The twigs will burn but will not ignite anything else. The firestarter and supercedar pieces still burn until they burn out, but nothing is causing anything larger to ignite for more than 2 minutes.

OP, you make it sound like you had just cut down that maple. Is that the case?

 

[rijim]

Can you tell us more about your complete install, chimney type, total height above fire box, number of bends, run inside or on outside of house, any dampers, etc...

 

[A M]

OP, you make it sound like you had just cut down that maple. Is that the case?

Yes, there were small pieces of maple that my friend had cut down that morning. I already know about fresh wood not burning (except in an outdoor furnace); however, because they were so small, I thought that there should be no problem with it igniting.

My friend only has "fireplace" and starting fires in them and outdoors. He has never had an indoor high-efficiency wood stove; as I stated though, I have a little bit of (learning) experience now within the last month and part of late winter last year; however, now I know that EVEN IF the fresh wood is SMALL, ... don't use it again, as you'll only get burn time for about one minute, blackened wood when it burns out after that minute or two, and apparently it will also affect any good wood pieces you place in there, that may cause them NOT TO BURN, as well.

 

[A M]

Can you tell us more about your complete install, chimney type, total height above fire box, number of bends, run inside or on outside of house, any dampers, etc...

If you are interested in this story, see my post called "Where's the heat, Myraid?" ... on hearth.com; gives all the specifics on this stove, details, etc.

 

[Ford850]

From all I've read and experienced, an OAK can indeed cause reverse draft problems. Depending on the wind direction for that day, it may be feeding air into the house or robbing air from the house. An easy way to check if you are having issues would be to check the OAK for air direction.

 

[clr8ter]

Yes, there were small pieces of maple that my friend had cut down that morning. I already know about fresh wood not burning (except in an outdoor furnace); however, because they were so small, I thought that there should be no problem with it igniting.

Ahh, see? I'm surprised no one else picked up on that. I'd dare to say you've found the majority of the problem. Not only is green wood hard to burn, (any size), but they say that the new EPA stoves are even more picky about it than the old smoke dragons. To clarify your problem further, I'd go find a know source of DRY wood. Wood which is known to burn real nice in an EPA stove. Bum a stove load of that wood off that guy, and do a test burn. That should answer any remaining questions.

I have also noticed that my stove is harder to run in warmer weather. Anything above 40, and it's a different stove. 30 and below, no issues.

 

[DougA]

or to block the outside (inlet) temporarily until you re-establish a positive flue draft.

That is a bad idea on at least some OAKs. My stove gets 100% of it's air supply from one opening which is 100% supplied by the fresh air kit when attached. If I were to block the outside opening, I'd be creating a very dangerous situation and starving the stove of all air.

On most wood stove OAKs, you should be able to simply remove the vent where it is attached to the stove and see if it makes a difference. This probably is not so easy on a ZC fireplace or an insert.

If the OAK is properly located and installed according to the stove mfg., and you have proper draft all the time, there should be no chance of the OAK reversing. The problem is in having a poor set-up. I've seen photos on this forum of fresh air supplies that are absolutely NOT correct. Add to that the numerous people who have drafting problems without using an OAK and you begin to see why people want to blame the OAK.

 

[Ford850]

That is a bad idea on at least some OAKs. My stove gets 100% of it's air supply from one opening which is 100% supplied by the fresh air kit when attached. If I were to block the outside opening, I'd be creating a very dangerous situation and starving the stove of all air.

On most wood stove OAKs, you should be able to simply remove the vent where it is attached to the stove and see if it makes a difference. This probably is not so easy on a ZC fireplace or an insert.

If the OAK is properly located and installed according to the stove mfg., and you have proper draft all the time, there should be no chance of the OAK reversing. The problem is in having a poor set-up. I've seen photos on this forum of fresh air supplies that are absolutely NOT correct. Add to that the numerous people who have drafting problems without using an OAK and you begin to see why people want to blame the OAK.

Excellent point. I edited my post.
Although the studies I found do not have the same results as you regarding the air flow 100% of the time. I think there are too many variables in terrain and airflow around strucures that can indeed pull air from a house through the OAK.

 

[DougA]

I have also noticed that my stove is harder to run in warmer weather. Anything above 40, and it's a different stove. 30 and below, no issues.

EXACTLY. The problems all relate to the physics of hot air rising. When the temperature difference between the outside air and the inside air is not great enough, the air doesn't want to rise.

A perfect simple example is a bonfire outside. On a still day, if you have lots of dry wood, there is very little smoke and the flames shoot straight up. Add green or damp wood and the smoke increases and blows in the faces of everyone standing around. Add damp leaves or grass clippings and all you get is a smoldering mess where the smoke hangs at ground level. Heat is needed to make it rise.

 

[DickRussell]

What DougA said. What I find myself doing on lighting off my stove (with OAK, in a tight house) is to leave the stove door open slightly for a couple of minutes, letting it draw from room air, until warm flue gas has filled the chimney, displacing the cold air in it. Then I can close the door and let the stove/chimney assembly draw from the OAK. Now, in my case the OAK duct has an inverted "U" of rigid metal pipe inside the wall, the idea being to create a "cold air trap" to prevent it drawing when there is no demand from the stove. I don't really know how well that works in practice, as I can feel some leakage out past the stove controls the next morning, long after the fire has died.

 

[DougA]

Excellent point. I edited my post.
Although the studies I found do not have the same results as you regarding the air flow 100% of the time. I think there are too many variables in terrain and airflow around strucures that can indeed pull air from a house through the OAK.

That's a fair comment and that's also why properly locating an OAK is as important as properly locating a chimney. For example, a wood stove in the basement could be a problem if the air supply has to come down to the basement. I see that a lot, even though it's not recommended according to the OAK instructions on my stove.

I know some stoves have an air inlet for the OAK, plus they have an inlet for indoor air. To me, that doesn't make sense in design at all and could indeed lead to problems. I was initially thinking of installing a damper on my OAK to prevent cold air from coming inside during the winter. Then it dawned on my that we run the stove 24/7 in cold weather, so why bother? I made sure my installation would allow me to make adjustments to the OAK if it was ever needed though.

I think there are too many variables in terrain and airflow around strucures that can indeed pull air from a house through the OAK.

That is impossible with my setup but may be possible on other stoves. If the doors are shut on my stove and the pressure reversed, the air would have to come from the top of the chimney to go out the OAK. The stove is sealed.

Still, if you have a good chimney with proper draft and a good fire going, I would find it impossible that a properly located OAK would pull air from inside the house. The real problems occur when using poor wood and poor draft with operator error. In the end, use of an OAK will always be a contentious issue. I would never recommend one unless the house is air tight and super insulated. It just doesn't make a lot of sense to me to use it on a house that leaks already.

 

[oconnor]

snip...

All an OAK does is to bring cooler outside air into the stove for combustion instead of using already heated air from the house. As long as your run is not too long or restricted in any way, it should not cause a problem. Remember to ensure that the outside vent is rodent proof otherwise it will make an excellent place for mice to make a home.

If I can be picky for a moment, it isn't about cooler outside air at all, but about pressure - the difference between pressure inside the home envelope (specifically pressure at the level the stove is installed) and outside.

A newer home has a finite ability to allow air inside for use venting the flue. Add exhaust fans for bathrooms and kitchens, clothes dryers etc and the competition for air to exhaust from the building can get intense. That is when you do not want the chimney to be the loser. The OAK (in theory) removes the entire combustion process from inside the home envelope - it draws from outside and vents outside, and allows the home air to be controlled by the other systems in the house.

It's all about stack effect, which is pressure changes related to heated air rising inside the home.

Other statements (advantages and pitfalls) about OAK above are reasonable. One thing to add would be that an OAK would reduce flue temps at standby as outside air would be circulating when a fire is not underway. In most flues, inside air is escaping, which serves to keep the flue warm, and results in better initial draft.

 

[rijim]

Unseasoned wood, warmer outside temps and short chimney are all problems an OAK can't solve

 

[Charles1981]

freshly cut wood no matter the size is not gunna burn very well at all. You can get it to burn but it would require multiple additions of newspaper under the kindling to get a hot fire and sizzle some of that moisture out.

once you had some coaling going on you could nurse the fire and add more kindling and work your way up to a full fire, but wet wood sucks.

 

[A M]

freshly cut wood no matter the size is not gunna burn very well at all. You can get it to burn but it would require multiple additions of newspaper under the kindling to get a hot fire and sizzle some of that moisture out.

once you had some coaling going on you could nurse the fire and add more kindling and work your way up to a full fire, but wet wood sucks.

I am in total agreement with you and also with rijim. The "wood" is almost everything ... for a successful heating machine. I'll never put small pieces of freshly cut maple into this stove. I have to say that the fire has kept going all day today and only around 300. When the late afternoon approached, I put in larger pieces of the wood I have, after examining the ends of it. Looked for the ends with lots of cracks in it. Anyway, this evening the temp is at 375 to 400. The living room is warm and the rest of the house is just fine. Only one room was really cold but its a room I don't use and always keep the door closed. This time, I opened the door and will leave it open, just in case the heat wants to travel down that hallway ... while I do not use that room, it would be nice to have it unfroze when I pass by it during the day.