OAK location for Harman Insert

jrex Posted By jrex, Aug 1, 2018 at 1:20 PM

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OAK pipe location

  1. in chimney above the block off plate

    2 vote(s)
    66.7%
  2. down through ash clean out to near window

    1 vote(s)
    33.3%
  3. skip the OAK

    0 vote(s)
    0.0%
  1. jrex

    jrex
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    Feb 14, 2006
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    Had a question on a new Harman insert install in a stone chimney with clay liner. Recent pulled out my Lopi wood insert and just picked up a Accentra 52i. I already pulled the 6" SS liner and received a new 4" SS liner. Been reading about the OAK benefit on lots of old threads here and pretty sure I am going that route. My dealer said if I wanted to save money try and run a year without and see how it burns but I figure if I don't do it now I probably won't later on.

    Ok so I read all the old threads. I was convinced I was going to buy the Harman chimey cap with louvers and run the OAK pipe half way up my 17' chimney. Here is the problem. The chimney has an adjacent flue that services my oil/coal boiler. This flue would be within a foot of the Harman cap. Should I be worried about taking in CO? Lets just say there is CO taken into the OAK from the adjacent flue does it even get out of the OAK/stove system?

    I do have an ash clean out in the back of the fireplace floor about 4x8 that goes into the basement clean out. I could drop the OAK pipe down there. Probably looking at 3' down and then maybe 10' horizontal to an unused basement window where I can run the pipe to. Would sit in a basement window well.

    No way to blow out the back of the chimney. It is all natural stone and is finished on the outside with stone.

    Any suggestions for either location?

    Thanks Jason
     
  2. Don2222

    Don2222
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    Feb 1, 2010
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    Hello
    If the top of your oil / coal boiler flue releases it’s gasses 1 foot higher than where the air comes into the Harman collar than you are fine, if not extend your Oil / Coal chimney 1 foot higher. :)
    I installed an oak up the chimney in a split entry on an existing pellet stove in a home that has all electric heat.
    Then we stuffed fire proof ROXUL insulation above the pellet stove on the damper shelf to completely stop heated room air from going up the chimney! This cannot be done without the OAK for combustion air!
    When comparing that winter season (which was not quite as cold)with the previous season, the electric bill was 8.7 percent less in electric heat used! If the winters were the exact same, I can easily see a 10% savings! That easily paid for the OAK and now it is saving some money$$
     
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  3. jrex

    jrex
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    Dont think I can extend the coal/oil flu. It is just clay no SS liner so I can not simply add on. Also there is a SS cap that covers all flues actually 3 but 1 is not used to cover the entire chimney. The SS cap sits about 12" above the end of the clay flue tiles. Thanks for the info.
     
  4. Don2222

    Don2222
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    There are lots of ways to extend a clay glue liner. :) see this thread
    https://www.hearth.com/talk/threads/extending-a-chimney-liner-bust-the-clay-help.125471/
    Also one flue cap over 2 or more flies is not recommended by today’s standards because of the downdraft it creates. That ss cap has to go if you really want to do it correctly.
     
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  5. jrex

    jrex
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    Feb 14, 2006
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    Ok Thanks for the link. I will have to take a closer look tonight at the clay flu and see if and how much it is above the concrete top plate. I originally went with the large SS cap to cover all 3 flues as I felt it gave a little more protection to the chimney from rain. No problem with back draft so far and I have had coal in 1 flue and wood stove on the other. The coal had a combustion fan that ran 24/7 and the wood was seldom used and never got coal small down the wood flue. But don't want to take any chances either.
     
  6. Don2222

    Don2222
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    Feb 1, 2010
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    Hello
    You do not have to use the Harman air collar although it makes it easy.
    When we do non Harman stoves we put a 4” SS liner down the chimney for the pellet smoke and a 3” Aluminum liner down for the air intake. They both will fit in an 8” clay block chimney as long as we cut the top plates to get them close together. Then the smoke pipe must be 1 foot higher than the fresh air pipe by code. This way no smoke will get into the fresh air pipe!
    Then we stuff the damper shelf above the stove with 100% fire proof Roxul insulation do not one bit of heated room air escapes up the chimney. We added a air intake 3” liner to an existing pellet stove in an all electric baseboard heat house. Th owner’s electric bill went down 8.7% the next winter. It was a mild winter so if it was just as cold then the savings would easily be 10% :)
    See pic below.
     

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  7. jrex

    jrex
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    Feb 14, 2006
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    Thanks Don. I came to the decision that I will do the OAK and will run it into the chimney. I ordered the Harman air collar last night off of ebay just because it was much cheaper than any place else. Looks like that gets attached to the masonary chimeny cap and then the SS flashing gets set on top and sealed with the 4" pipe and cap above it. The 3" OAK pipe I will run half way up the chimney.

    Probably will end up with 1 of those add a flue extensions on the adjacent flue to raise it 12".

    How do you get all that insulation in the chimney above the block off plate? Do you drop down from the top of the chimney? I have a buddy with a small shop and will see if he can make me a block off plate for the 3" and 4" pipe.
     
  8. Don2222

    Don2222
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    Since you need a new block off plate, just put the insulation in before you attach the new block off plate. That is the best way.
     
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