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Outside Air Kit Questions...Again

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by wilbilt, Nov 30, 2007.

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  1. wilbilt

    wilbilt New Member

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    I am still trying to locate an outside air kit, literature for one, or even a photo of one for my old Trail Blazer stove.

    I can fabricate one , as it seems pretty obvious as to how it would function, but I'd like to be sure.

    After looking inside the stove the other day, I confirmed there is only one fan serving combustion, convection and exhaust. This means that with an OAK installed, it would not only be using outside air for combustion (good), but also for convection (seems bad).

    It seems that continuously trying to heat frigid outside air and push it into the room would not be very efficient.

    I have read that the main purpose of an OAK is to avoid negative pressure in the home, but in this case, wouldn't it cause positive pressure? Would I have to open windows to get any heat out of the stove?

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  2. thephotohound

    thephotohound New Member

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    Unless your home was built in the last few years, I doubt negative pressure would be an issue. A home has to be incredibly airtight for that to happen. With that said, I would ALWAYS keep multiple CO detectors around and functioning. Re: an average or drafty home, I would think that NOT installing an OAK would force the stove to pull combustion air from the level of the inlet (usually near the floor) eating up the cooler air that sits on the floor. I'm no physics expert, but it makes sense to me...
  3. wilbilt

    wilbilt New Member

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    I always crack a few windows open when burning, and can feel a slight draft from them.

    I am all for using outside air for combustion, but with the design of this stove, that would also mean heating outside air for convection instead of recirculating (heated) inside air.

    If the house is tight enough, no heated convection air would be extracted, and no point to burning.

    There has got to someone out there familiar with this stove...
  4. gpcollen1

    gpcollen1 Minister of Fire

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    I am confused...just because you have cold air coming in the window does not make it a 'draft' as in it is being 'pulled in' b/c you are using internal air for combustion. Open the window without the stove on and I bet the cold air still comes in. Cold air moves to warm---

    That design does not make sense and I would think you have it wrong. The air you are warming by combustion should go up the stack. The air you are warming for the room should come from the room. Any reason the design of the stove (1 fan - are you sure) could not accommodate this?
  5. wilbilt

    wilbilt New Member

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    The basic design is similar to many other stoves, i.e., there is a hopper on the top with an auger that moves the pellets up to the feed tube where they drop into the burn pot. The firebox is at the front, with the heat exchanger tubes running through the top to holes in the front of the stove.

    The difference is that behind the firebox, there is no ducting to separate the pressurized combustion air from the pressurized convection air. There is a single fan mounted to the bottom of the stove that essentially pressurizes the interior of the stove below the hopper and behind the firebox. This air then flows through holes in a baffle to the area under the burn pot to support combustion as well as flowing out through the heat exchanger tubes.

    The exhaust exits the top rear of the firebox and goes straight out the back of the stove. There is a shroud around it where it passes through the hopper. Pressurized air also passes through the shroud around the exhaust and exits through a couple of louvers next to the stack connector on the back of the stove. I assume this recovers a bit of heat from the hot exhaust as well as cooling the pipe as it passes through the hopper area. There is no exhaust blower that I can see.

    The fan draws air from below the stove body in the area of the pedestal base, which is open at the rear. There are flanges on either side with screw hole that I assume would be for a plate to close off the rear of the pedestal. There is a knockout in the bottom of the base for an outside air pipe to exit below the floor. My plan was to fabricate a plate for the rear of the pedestal, attach a pipe flange to it, and draw outside air through the wall behind the stove.
    EDIT: here is a crude drawing...
    [​IMG]
  6. please302

    please302 New Member

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    To all of those who are quick to give an opinion about outside air kits please be weary. I have read a lot of negative comments about oak and how they dont work or matter. However, I had just recently bought a p68 and had it installed on dec 1. The stove was installed downstairs in the finished basement of a dutch colonial house with the finished basement, 1st and 2nd floor with center stairs for both floors. The house was built in 1951 with updated windows and I just stuffed the attic with insulation this past spring. The house is not noticeably drafty. Anyways, at the time of the install the installers who have been a family wood stove/pellet business for years talked me out of the oak. For me it was not the money but rather the way they had explained it's terrible looks (a dryer vent pipe next to the exhaust pipe) and the supposed "facts" that they gave me about how it would not be a great benefit as everyone makes them out to be. I was wondering at first who he was talking about when he mentioned "everyone? The blogs, the manufacturer? The installers stated that the only reason that they use them is for clearence purposes on the install. They stated that although there is better efficiency obtained by the stove and it is easier to get it cleared during inspection ( hummmm, safety?) that the benefits are hardly recognizable. So I said ok, thinking that if I decided later to install one I could just do it myself since it is the same as installing an dryer vent and it would be cheaper if I did the work opposed to a pro installer. So I began to use my stove which was great in every way. The heat was great and maintenance was a breeze. I didnt have any of the problems that I had read everyone talking about on this website even though I was worried about the PENNINGTON PELLETS that I had bought before I saw what a fiasco that they had been the year before. ohh by the way I just noticed when I poured some pellets into the hopper that there was a 5" piece of wood chunk in the bag of PENNINGTON PELLETS but thats another story for me and PENNINGTON to duke it out. Anyways, the stove was great but as time went on approx. 2 weeks I did notice a "draft" near my feet downstairs where the stove was installed. I also noticed drafts on both sets of stairs and noticed that upstairs was not getting warm and figured that it was just too far away from the stove. I also figured that the "draft" was actually the cold air dropping and the hot air rising and displacing the cold air. I was surprised about the strength of the draft on both stairs however. It was just more then I expected but maybe it was normal, how do I know. So after 2 months of constantly using the stove for the main heat source I began to think with every cold draft that I felt whether the oak would matter in my house. I finally decided to install it myself about one week ago and it was actually pretty easy, taking only a few hours of drilling,caulking and fitting. After I was done I turned it on and got ready to compare the results with and without the outside air kit since I had used the stove for a month and had a good idea of what it was capable of. The results were so drastic that i noticed them right away. The "drafts" on the stairs were greatly diminished and the heat of the stove spread upstairs much quicker and heated even the 2nd floor which it had not done before. The heat from the stove was greater which was obvious. I had the heat on 3 and 1/2 and the fire was still huge and it heated the 2nd floor on a 20 degree night to 71 degrees. In the past even with the heat cranked up to 6 I could not get it over 68. I honestly believe and now have, although not scientific, some obvious evidence that in my case the oak made a hugh difference in heat output, efficency, increase in heat radiation and travel throughout the house in areas where I could never feel the heat before. I do think that air is allowed now to move more freely and farther into the house and so areas are able to heat up that never use to get heat and areas that did get heat are hotter. I am not sure if it has something to do with the resistence that is being overcome by having the oak but the difference is undeniable. SO to all of those with opinions that seem to make sense, there are a lot of factors that end up influencing the final outcome which in my case speaks for itself. And to all of those who are questioning whether or not to put an oak in their home I would just tell you to look at my results and look at their own particular situation and decide. Good luck.
  7. krooser

    krooser Minister of Fire

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    I didn't even question my dealer when I bought my stove and the vent kit included a self-contained OAK. They simply told me that's the kit they recommend and i went with it. Seems to work perfectly.
  8. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    wilbilt,

    I'd never put an OAK on that particular type of stove. It is "bad" enough as it is.

    You have something a lot different than the "negative pressure" separated air flow stoves.
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