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

    3 vote(s)
    75.0%
  2. down through ash clean out to near window

    1 vote(s)
    25.0%
  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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    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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    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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    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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    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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  9. jrex

    jrex
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    Ok here is where I am at with the install.
    1) while on top of chimney I coated the crown with some crown RX its a white elastomeric coating to fill any small cracks and prevent water seepage
    2) installed the Harman vented SS cap on top of the crown.
    3) dropped the SS liner down the chimney
    4) put a flat 18x18x6 hole cover over the Harman vented cap which the liner travels through. I siliconed and screwed this to the Harman vented piece
    5) installed a SS chimeny cap on top of the liner with spark arrestor
    6) stuffed some rock wool up the masonary chimney
    7) attempted to put a metal block off plate in the chimney, this part is a pain since it is hard to reach and crap is falling in my eyes (safety glasses on though) and the steel that lines the fire box is 1/4" so hard to fasten my plate too. Its not perfect but with the insulation should stop most room air from escaping.
    8) pushed a 3" aluminum pipe up through the metal

    Will post pics when I am done.

    I assume its OK for the rockwool to touch the liner?

    Just prepping the Harman cage for install. Looks like 4 bolts get screwed in to act as leveling feet for the base. I assume it gets put into place and then you just screw the bolts down to level as needed. Does this seem correct?
     
  10. Don2222

    Don2222
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  11. jrex

    jrex
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    Yes that is the 1 I got. I put it together so it just sits 1/2" wider than the clay flue liner. I then marked each side even with the adjacent piece nail flange, took it apart, and then trimmed each piece with a tin snips because it was way too big for my flue which I think was 11x11. Then I screwed it back together. I then ran a bead of silicone on the chimney crown where this piece sat and attached each side with 2 tap con screws. Then I ran another bead of silicone on the top edge and screwed down a 18x18 flat SS piece that has the hole for the 6" pipe. Let me see if I can figure out how to add pics.
     
  12. jrex

    jrex
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  13. jrex

    jrex
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    I don't have it screwed down in this pic but I put 2 tapcons on each side. On top sat the 18x18 piece. I haven't cut the liner yet. Once that is done I have the cap the goes on top.
     
  14. Don2222

    Don2222
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    Looking good so far! Make sure you silicone all the small holes on the side next to that open flue so no smoke gets into the air collar!
    The code is all smoke flues should be 1 foot higher than the air collar so wind does not push any smoke into the air collar and down the chimney.
     
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  15. jrex

    jrex
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    I thought about blocking off the holes on that side but I don't want to get to a point that I don't have enough air so just going to do an extended flue on the 1 side. The other side isn't used and just leads to an outside grill.
     
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  16. jrex

    jrex
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    Ok I think I am done with the install.
    Chimney Vent.jpg Chimney Done.jpg
     
  17. jrex

    jrex
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    A few issues I had when installing the Accentra Insert.
    1) Block of plates are a pain depending on the geometry of the masonary chimney. I can see why some installers try and get away with just stuffing some insulation up there. I used ROckwool and some thin sheet metal I got from a local shop. Turned out OK.
    2) Not sure why Harman just doesn't give you stub on the stove for SS liner. I would think that is how most are installed. I had to run around looking for a 4" appliance connector to make a tight connection from liner to stub. I think I could have done it without but tough to get the liner into their stub mre than an inch.
    3) The surround that gets bolted to the cage had to be held as high as possible to allow for the insert to slide in. I bolted the 2 side pieces and top on while it was sitting on my hearth. The stove would not slide in it and Stove Final.jpg hit the top piece of the surround. I had to unbolt the entire thing and move it up about 1/4". There is some play. The side pieces actually sit a hair off of the hearth.
    4) not Harmans fault but I plugged into the air sensor. It plugs into a board and looks like they give you the sensor with a short length of wire and also a long piece of wire for an extension if you want to run the sensor out and down the wall. Well I used the short piece but left it coiled up and never ran it out of the stove so I will have to pull the stove before I use it to run the sensor out. I may buy the remote sensor so I am not sure if the wired sensor is still needed.
     
  18. Don2222

    Don2222
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    Good work JRex
    This makes a great reference post!

    Harman does not have the exhaust flange on the stove so you can pull the stove out for easy servicing.

    The stove adapter does make a good fit, you can do without it if you seal the flex liner with high temp silicone caulking and self tapping screws into the pre-drilled holes.

    Many other stoves must have the Surround disassembled for servicing. Harman makes it easy. :)

    There is a hole in the frame to run the room sensor out,
    Then it should be up 4 - 5 feet on the wall to read the room temperature properly. I use the 3M no damage clips to hold the end of the sensor. They work very well!

    Did you install the optional air adapter on the intake in the back of the stove?

    Do you have pics of the fireproof rockwool Roxul insulation and sheet metal blocking plate above the stove in the chimney?

    Are you going to purchase the rail kit for servicing or using 2x4s build your own?
    I use a wooden box with shims because different stoves on raised hearths are different heights. :)
     
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  19. jrex

    jrex
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    Feb 14, 2006
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    I understand the liner not on the stove so you can pull it out. All I was saying is the stub on the frame should come with more of the appliance fitting so it makes it easy to attach the liner. I purchased a separate appliance fitting. Attached that to the stub with 3 screws. Then slid the liner and connected with the hose clamp type attachment. Both seams were siliconed.

    Yes I purchased the Harman OAK kit. So you take off the intake that comes with the stove. Think it was 2 bolts. You must remove temporarily 1 of the fans. The OAK kit gets mounted to the intake, screwed to the pellet bin, and then you also get a 3" stub that attaches to the back of the frame just like the exhaust stub.

    I forgot to take pics of my block off plate. My 4" liner hole ended up being more like 6" but that was Ok because after the plate was fastened I was able to stick more rockwool up the hole. Fit was decent and should keep most of the hot air from going up the chimney.

    I did not purchase the rail kit. My hearth is 3/4" above the floor level. For now I just used a sheet of 3/4 ply. I still need to find some metal the thickness of the rails on the Harman frame. I will attach the metal to the 3/4 plywood and let it over hang the plywood the depth of my hearth to but up against the Harman frame.

    I wanted to make a fire last night but my wife said no way. I did pick up a ton of Lignetics for $250.
     

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