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QUESTION ABOUT AN OAK

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by leoibb, Dec 4, 2012.

  1. ScotO

    ScotO Guest

    B of H, I used 1" thick insulation and overlapped it by half, only did it around 5' into the space. i wish I could have insulated it the whole way but I couldn't do it, on count of the way I had my OAK mounted. As for a trap, just make a hump "upwards" with your flexible pipe (creating a little "hill" that the air has to get up and over). My OAK works pretty darn good.
    John_M and bag of hammers like this.

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  2. El Finko

    El Finko Member

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    Thanks Scotty. Did you use the corrugated dryer-type hose for the entire length? Since air acts like a liquid I wondered if smoother PVC pipe would be necessary for a run that long (obviously not right up to the back of the stove, though- I'd use the metal stuuff close in).
  3. ScotO

    ScotO Guest

    I used some galvanized 4" pipe and elbows, but half of the run is the flexible aluminum dryer vent pipe. It will work fine for that application.
  4. bag of hammers

    bag of hammers Minister of Fire

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    Great to hear - and thanks for the additional info...
    ScotO likes this.
  5. leoibb

    leoibb Member

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    interesting points. the oak will only travel approx five foot to an exterior wall
  6. John_M

    John_M Minister of Fire

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    In his post "26 of this thread, Hearth.com Members mentioned making a hump in the 4" flexible pipe feeding the OAK. I want to follow-up on this excellent suggestion::cool: When you form the hump, the bottom arc of the hump MUST BE slightly higher than the top of the straight run on the intake side of the hump. Hope this description is clear enough...this is another example of how one picture would be worth a thousand words.:)

    How do I know this? Because about 24 years ago while living in Alaska I had to form this hump for a fireplace installation. The only time the hump prevented FREE FLOW of cold outside air into the fireplace was when the hump was bent as described above. The hump DOES NOT interfere with drawing cold air into the fireplace with a fire burning.

    Happy holidays!
    ScotO and bag of hammers like this.
  7. bag of hammers

    bag of hammers Minister of Fire

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    guys this is great info- thanks. the outside vent hood I installed is in the center of a rim joist - the horizontal run from hood to stove was intended to go flat across to the stove, between 2 floor joists (up out of the way for the full run) then 90 deg up into the pedestal. I think I might have mentioned somewhere that Osburn recommends a 5" pipe (which I now have) which would not allow me enough "head room" to do as you mentioned (assuming the hump is bent upward). So - would it matter if I bent the pipe downward instead - same idea -but in this case, the arc in the hump would be below the bottom of the straight run - again no free flow - like taking the suggested design, an "inverting" it. What to you think?
  8. John_M

    John_M Minister of Fire

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    bag of hammers, Your modification probably would accomplish the same goal. The cold air probably would not cimb out of the dip unless encouraged to do so by a "draw" from the stove. However, the dip might accumulate moisture/ice, debris, etc. sucked in through the vent hood by the burning fire. If that section of intake pipe has easy access it might be worth the experiment. Heck, it might even be worth the experiment if the dip is somewhat difficult to access.

    I do believe that if your "dip" modification to Scotty's idea works, you will be very happy with the results.

    Good luck and best wishes! :)
  9. bag of hammers

    bag of hammers Minister of Fire

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    This is a fairly easy spot to get to (my crawl space has inside access) so that might be the plan. Now that I'm thinking about it, it's kinda like a p-trap for the stove air flow. I never would have thought of this if not for Hearth.com Members and yourself. Definitely worth a try. Thanks again.
  10. Machria

    Machria Minister of Fire

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    So the purpose of the hump would be o keep cold air from entering the stove when it was not in use?
  11. Hogwildz

    Hogwildz Minister of Fire

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    This makes no sense.
    If your drawing cold air from outside with the AOK, how is this helping the stove draft faster?
    I can understand using the torch to heat things up, although you have a draft issue to start with if needing a torch to get it to draft every time you light it.
    But AOK air is much cooler, even colder than if it was taking inside air, so it would help draft less than the warmer inside air.
    Sounds like wishful thinking to me.
  12. Hogwildz

    Hogwildz Minister of Fire

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    Ain't bying that one, but hey, whatever sets your mind at ease.
    Heating the same "stale" air constantly, is going to be a hell of a lot drier than air infiltrating from outside.
    AN outside source of a humidifier would benefit both ways.
  13. leoibb

    leoibb Member

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    interesting topic but after all done its a fire nothing more or less, i don't think it needs to be so technical , i clearly understand the hump as cold air would struggle traveling over it. (cold air sinks is my thoughts) when the fire is burning then it would pull the air through, but when fire isn't burning i think it would need some shut off device or it still would suck the air slightly, just my thoughts on it.
  14. John_M

    John_M Minister of Fire

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    Machria, you are correct...the purpose of the hump is to prevent cold outside air from entering the stove when it is not burning.

    Allow me to add one more clarification to what I have posted above: If your stove is located above the OAK air intake, as seen in the second link I posted in my reply #19 above, there is no need to bend a "hump" into the OAK intake pipe. The cold outside air will not travel up the vertical pipe to the stove unless an outside influence (fire in the stove) causes it to do so.

    For example, my OAK intake pipe has a 3' horizontal run from the OAK intake hood to the 90 deg. elbow where the intake pipe goes vertically about 3' to the bottom of the stove. Cold outside air DOES enter the 3' section of horizontal pipe but that air DOES NOT travel up the vertical pipe when when there is no fire in the stove. How do I know this? Simple-on a cold day when there is no fire in the stove I open the stove door and feel the intake slits just beneath the door. They appear to be about room temperature and certainly aren't cold. On a VERY COLD and WINDY day when there is no fire in the stove, I can sometimes feel a cold draft coming DOWN the chimney, into the firebox. However, that situation is so infrequent as to not attract my attention.

    For the record: I have no personal interest in whether someone does or does not have a woodstove, an OAK, or a hump in the OAK feeder tube. My only purpose in participating in this thread is to provide my limited experience in the matter. Readers are encouraged to pick and choose tidbits, if any, which interest them.

    Now, I am off to place a couple of large maple splits on the simmering coals in my Spectrum.

    Best wishes, good luck and happy holidays to all. ;)
  15. metalsped

    metalsped Burning Hunk

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    That is the thing though... its not 'heating the same stale air...".. its physically consuming it, and it gets replenished by slight insulation leaks and similar constantly. With an OAK, you are pulling exterior air, which has no effect on the air in your house.
    John_M likes this.
  16. dorkweed

    dorkweed Guest

    OAK's only supply "primary" air, correct???? So when cruising; with secondaries dancing, you have the primary air damped mostly down....................the stove is drawing "inside" air to the secondary tubes and the doghouse from other locations on the stove. Well with my stove anyway.
  17. dorkweed

    dorkweed Guest


    Bump to the top.

    Can anyone answer my question??? I understand the theory behind the OAK's, but what if your stove pulls doghouse and secondary air from "other locations on the stove..............not being OAK supplied???? Kinda defeats the purpose in some way............hey???
  18. John_M

    John_M Minister of Fire

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    dorkweed, I am not familiar with the Englander line of stoves. Therefore, any info I might offer would be a hazardous guess at best. One can assume you are looking for reliable info and not hazardous guesses.

    Good luck and best wishes.:cool:
  19. dorkweed

    dorkweed Guest

    Danke'.:)
  20. metalsped

    metalsped Burning Hunk

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    I do not know for sure.. but yes, I believe it is primary air only. I think that is how these newer stoves are developed... so that you always have SOME air going to the flame (ie... no smoldering). Totally different air path for the secondary fire.
  21. dorkweed

    dorkweed Guest



    Thanks............................However; the silence is truly deafening!!!!;hm
  22. John_M

    John_M Minister of Fire

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    dorkweed, what is "doghouse" air? I am unfamiliar with that word when used in a woodstove discussion. Perhaps others share my ignorance and therefore do not know how to respond to your query. Another option for you is to start a new thread on just your topic to draw new attention to your interest. There appear to be quite a few Englander 13NC owners on this site and they are always generous in sharing their knowledge with others in need.

    Just a couple of thoughts!

    Best wishes and good luck.;)
  23. blwncrewchief

    blwncrewchief Burning Hunk

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    Stoves are different in design. On my stove the OAK feeds 100% of the air, primary and secondary. Also on some stoves, I "think" the Englander is like this, you have to have the pedestal and it acts as a "plenum" for the air feeds in different locations. So you have to know how your stove is designed to answer this.
  24. Treacherous

    Treacherous Minister of Fire

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    I just discovered this today from another thread....

    My secondaries are pulled from inside air.

    I don't have an OAK but my Lopi pulls it's secondaries from rectangular ports behind the heat shields on the sides a few inches from the bottom. The OAK for primary attaches to a cutout on the bottom of the stove. Through this cutout you can view the opening/closing of the primary air.
  25. Berner

    Berner Member

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    Would locating the OAK on the leeward side of the house be a good idea? Would putting it under a porch be a better idea? I have a choice of one or the other.

    Also any of you Progress Hybrid guys know where the OAK connection to the stove is? Jut trying to get all my ducks in order before I cut the hole in my floor.

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