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OAK - My dealers perspective.

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by gerryger, Oct 24, 2011.

  1. sinnian

    sinnian Minister of Fire

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    Combustion occurs somewhere around 1600-1800 degrees F for wood pellets. I highly doubt 30-50 degree F air (it WILL warm up before it gets to the chamber) would have that much effect on the combustion of your pellet stove.

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  2. checkthisout

    checkthisout Feeling the Heat

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    It depends on what setting you have your stove on. On mine on the lowest setting, warm vs cold air is the difference between the fire staying burning or burning itself. Less heat in the burnpot area means less heat to maintain the fire and more frequent bouts of smoking. Under a higher, more steady feed-rate there is a noticeable difference in deposits in the burn pot.

    It's also worth noting that during the winter, many people would be drawing in air that measures in the lows teens to below zero range.



    Combustion efficiency aside, heating the OAK air with waste heat from the chimney is recovering free heat and making you burn less pellets.
  3. RKS130

    RKS130 Feeling the Heat

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    For what (little) it is worth, here goes. I am a newbie Harman Accentra owner - just installed this week and loving every moment of it! The owner of our dealer recommended OAK but his son, who ultimately wrote up our order, was against it. We went with the OAK. Seems to me that the temp of the air used for combustion is immaterial. It will get plenty hot as the pellets burn and the 40 or 60 degree difference makes no change at all.
  4. Jim H.

    Jim H. Feeling the Heat

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    I figured I would chime in as well. I ran my XXV without the OAK for the past 3 years or so....You could definately feel the air moving toward the stove....(outside cooler air?) Now for the last month I have the OAK on and I have laid on the floor and no draft! Fire is HOT! All the literature states it will burn more efficiently with the oak. So I am a believer now! LOL
  5. cold front

    cold front Member

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    The st. croix stoves are set up in the factory to draw room air for best efficiency. It's optional to to install a cold air intake and required if you live in a trailer. My dealer also does not recommend the cold air intake for some of the same reasons the first poster stated also because you have to mess around with the settings.

    I think the issue of cold air being drawn into your house is a moot point because of the 2nd law of thermodynamic that states that heat moves toward cold.

    Anyways, not wanting to change my pipe thimble or poke a hole in my roof, I covered my cold air return with sheet metal on my forced hot air furnace cut a hole the size of a of the flexible aluminum pipe and attached the other end to the cold air intake on the stove. now I am drawing air from my cold basement. I hoping that a little more warm air will flow down there plus the stove gets the denser air to burn.
  6. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    Heat yes air flow due to a pressure difference no, the air will flow into the lower pressure area and that my friend in a house burning without an OAK is into the house via every crack there is from outside of the house.
  7. cold front

    cold front Member

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    Is not the reverse true also? If you create a positive pressure with the OAK you are blowing hot air out those same cracks all over the house. I maybe a zero sum gain with an OAK, but one thing is for sure you can achieve better combustion with an OAK just like a cold air intake on a car.
  8. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    No positive pressure is created inside the house by an OAK.
  9. Xena

    Xena Minister of Fire

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    Same experience here. For the first three years I couldn't figure
    out why my feet were cold while sitting 6 feet away from the
    pellet stove and thermostat on the wall showed 75 degrees.
    Got down on the floor and felt the breeze. Installed an OAK
    and that breeze went away and no more cold feet.
    In a case like this an OAK will make a difference. Not saying
    all setups need it or can benefit but mine sure has.
  10. DexterDay

    DexterDay Guest

    Smokey is correct.

    Without an OAK. You have created negative pressure in your house. Now drawing cold air from, well, everywhere.

    With an OAK you have neutral pressure as the OAK. Or no pressure difference. The air being blown out of the house is replaced by the same amount through the OAK. Thereby increasing efficiency.
  11. jtakeman

    jtakeman Minister of Fire

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    This here debate will go on and on and on!

    The air draw to in home draft should be a given. The stove sucks in air creating low pressure inside the house. What ever leaks will leak in cold outside air you would need to reheat. At least I hope that's the case?

    How the heck are we going to debunk the cold air and fire issue? I'll volunteer to be the Ginny pig on this once I get my data logger/s. But what do we need to record. Convection air doesn't debunk it. So we need to measure exhaust temps and air temp/humidity. Do we also need to measure the burnpot temps?

    Just asking.
  12. stoveguy2esw

    stoveguy2esw Minister of Fire

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    ok, im gonna take my swing at this one:

    virtually any structure will have some degree of negative pressure especially low in the stucture, houses in general have devices that remove air from within anyway (range hood, bathrom vent , clothes dryer is a biggie, even your chimney) this air will leak back in as houses are not hermetically sealed but its never a molecule for molecule thing.
    that said the other dynamic is that air inside of a structure if its warmer inside than outside will rise , just as it does in a chimney, but unlike a chimney the roof traps it to an extent, this causes moderatly higher pressure in the upper regions of the structure and lower pressure in the lower when compared to ambient outdoors. most heating apliances are located low in a house and below the "zero pressure plane" of the building (where pressure is equal to outdoors) so even in an older leakier house you can have negative pressure in the lower levels. the "tighter' the structure the more pronounced this pressure gradient will be and thelarger the differential temp between inside and out increases this as well (again just like in a chimney)

    now , you add to this a device actively removing air from this already lower pressure area you increase the negative pressure. using an OAK takes this completely out of the equasion.
    as forthe "positive pressure aspect mentioned above , think of it this way, you have air in house that you warm up , it expands so it does actually create a slightly higher pressure (or at least reduces the negative pressure from expansion thus reducing the structures "inhalation" of air through leaks

    last but not least , once the house is up to temp , you are enjoying heat you have paid for with fuel, why would you want to suck this air out and blow it outdoors? especially when your house would then revert to inhaling cold unheated air in to replace paid for heated air you used for combustion and blew outside.

    to me its a no brainer, oak simply must be more efficient than burning using indoor air
  13. mike56

    mike56 Member

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    stove manufacture says to use an OAK that's good enough for me.
  14. slls

    slls Minister of Fire

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    Most new oil fired furnaces or boilers require OAK.
  15. jdempsey

    jdempsey Feeling the Heat

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    Thats the exact the reason i bought my pellet stove. The wife says it makes her hot.
  16. save$

    save$ Minister of Fire

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    As stoveguy and others said and explained to the enth degree, "to me its a no brainer, oak simply must be more efficient than burning using indoor air". I have one installed, but I went two years without one. Big mistake on my part. Who knew listening to the installer would be not in my best interest. Then I got some bad advice about installing it with PVC. All corrected and working very well. My OAK will get a little frosty during very cold nights, but I can't find any negative outcomes. No dripping etc. 4 Th year now, and everything just humming along! Just remember, OAK isn't OAK unless it is connected to the outside.
  17. nailed_nailer

    nailed_nailer Minister of Fire

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    Ok so you guys have me thinking......

    How can we prove or disprove the OAK argument.
    Perhaps I am biased so feel free to entertain my argument. I believe Ambient temperature has little effect on Stove efficiency.

    I dug around the web a bit and have a few calls into some of my math heavy buddies. (The kind of people that get drunk and solve equations for fun)
    I'll let you know what they come up with.

    Meanwhile.....
    I did find a paper from the NIST site talking about proving an equation parameter where flame heights were recorded with a change in Ambient temperature.
    The math is not my strong suite but I think it shows (in a limited data set) that there was no appreciable change in flame height with a change in Ambient temp from -17C (~0 F) to 27C (~80 F)

    http://fire.nist.gov/bfrlpubs/fire97/PDF/f97109.pdf
    See Table 1 Tests 11-16 Value L is the Flame Height

    Running after the wind......
    ---Nailer---
  18. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    Several of the national labs conducted many test on a large number of combustion factors and stove efficiency factors, they did this testing for the beloved EPA.

    Perhaps I'll see if my Google Fu is still working.
  19. checkthisout

    checkthisout Feeling the Heat

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    I purchased mine as an Xmas present for my wife as well.
  20. St_Earl

    St_Earl Minister of Fire

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    my girlfriend has been taking her clothes of since the stove started running.
    two more layers to go. lol
  21. PA_Clinker

    PA_Clinker Member

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    So far, this is what I've come away with from this thread; If a stove has an OAK inlet that leads directly to the burn pot, then it's generally a good idea to utilize it.

    Now, what about the stoves equipped with an OAK inlet that do not have a direct connection to the burn pot? Seems to me that punching another hole through the wall and running a hose that basically terminates open to the home is like having a window constantly cracked open. So, in this case fuggedabout the OAK, right?
  22. heat seeker

    heat seeker Minister of Fire

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    That's my opinion on it!
  23. gerryger

    gerryger Member

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    I started this thread and have listened to many of the responses and despite the claims of my dealer and many others that an OAK is not needed, I did decide to order an OAK from an online distributor (not my dealer). First, the main reason for this is the simple fact that I do feel pockets of cool air around the room. As far as the physics of what goes on in the burn pot regarding cold air, heated air, humid air, I could care less. It's beyond my intelligence. The bottom line is I want to stop the cool air pockets and I think an OAK is the only way to do that. I guess I have to spend a $100 to see if it is true.

    Upon my attempt to order the OAK the rep told me that they do not stock them because he doesn't see the need for them, however it could be special ordered. He then stated that he hasn't sold one in awhile and said only mobile homes need them. He really tried to talk me out of a sale. This is the second time that a pellet stove dealer could have made a sale of an OAK and they told me not to bother. I find it amazing. I still ordered it.
  24. smoke show

    smoke show Guest

    Please update this thread post installation with your thoughts.
    thx
  25. TLHinCanada

    TLHinCanada Feeling the Heat

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    While I find the pro and con argument's interesting, I think you are missing the safety reason. If you have another combustion source that uses a chimney with a flapper vent and it is running at the same time as your stove you need a oak. By creating a negative pressure you could be sucking CO back into your home.

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