1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)

Relationship between chimney draft and height

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by dafattkidd, Oct 11, 2013.

  1. dafattkidd

    dafattkidd Minister of Fire

    Joined:
    Dec 11, 2007
    Messages:
    1,572
    Loc:
    Sound Beach, LINY
    I generally run my unit pretty hot. 500-700 range is normal. I get spillage pretty much always. I think last year we had a couple of super cold days, and on those days the spillage seemed less. This is when I started considering extending my chimney.

    I also think the offset box contributes to my problem.

    Helpful Sponsor Ads!





  2. oldspark

    oldspark Guest

  3. Jags

    Jags Moderate Moderator Staff Member

    Joined:
    Aug 2, 2006
    Messages:
    15,272
    Loc:
    Northern IL
    Temps sound good. Back to staring down the chimney.::P
  4. mellow

    mellow Resident Stove Connoisseur

    Joined:
    Jan 19, 2008
    Messages:
    3,537
    Loc:
    Salisbury, MD
    You need more draft to compensate for that offset box, a 90 in a chimney takes off 5 feet in overall length, so I would guess an offset box takes off 8 feet.
    Woody Stover likes this.
  5. oldspark

    oldspark Guest

  6. Sprinter

    Sprinter Minister of Fire

    Joined:
    Jul 1, 2012
    Messages:
    2,072
    Loc:
    SW Washington
  7. brenndatomu

    brenndatomu Minister of Fire

    Joined:
    Aug 21, 2013
    Messages:
    627
    Loc:
    NE Ohio
    Sorry, maybe this was already covered elsewhere, but I'm assuming you have a masonry chimney with SS liner? Is it insulated? That would add some draft if it was.
    As to one of your original questions, how to extend your chimney height, again, assuming masonry chimney with a SS liner. They make a top plate that adapts from flex liner to class A pipe. I know I have seen a link to one here somewhere before, maybe someone else can put their finger on it more quickly than I.
    I have no experience with those draft inducer fans, but to me, that looks like a real PITA on a wood burner chimney...
    Last edited: Oct 11, 2013
  8. Woody Stover

    Woody Stover Minister of Fire

    Joined:
    Dec 25, 2010
    Messages:
    5,804
    Loc:
    Southern IN
    So you don't have a full-length stainless liner?

    "The chimney must have an acceptable 6" (152 mm) stainless steel chimney liner installed."
    "The 2400 Insert is not approved for use with a positive flue connector into a masonry flue."

    Terminology differs, but what they are calling a 'positive connection' is what I call a 'direct connection,' where the stove connector pipe goes up through a block-off plate, then uses the masonry chimney clay liner tile the rest of the way up. They are saying this is a no-no. I call a liner all the way up, a 'positive connection.'
  9. dafattkidd

    dafattkidd Minister of Fire

    Joined:
    Dec 11, 2007
    Messages:
    1,572
    Loc:
    Sound Beach, LINY
    I have a 6" liner running from an offset box which is directly connected to my stove. The liner goes up to the cap. Only the lower and upper portions of the liner are insulated.
    Last edited: Oct 11, 2013
  10. mellow

    mellow Resident Stove Connoisseur

    Joined:
    Jan 19, 2008
    Messages:
    3,537
    Loc:
    Salisbury, MD
    He has a liner, he just put insulation at the top and bottom instead of the whole thing.
  11. Woody Stover

    Woody Stover Minister of Fire

    Joined:
    Dec 25, 2010
    Messages:
    5,804
    Loc:
    Southern IN
  12. Woody Stover

    Woody Stover Minister of Fire

    Joined:
    Dec 25, 2010
    Messages:
    5,804
    Loc:
    Southern IN
    OK, gotcha.
  13. oldspark

    oldspark Guest

    If it is a inside chimney (I think he said it was) the insulation is less of a factor.
    Woody Stover likes this.
  14. Woody Stover

    Woody Stover Minister of Fire

    Joined:
    Dec 25, 2010
    Messages:
    5,804
    Loc:
    Southern IN
    I don't see an actual minimum flue height figure listed....
  15. oldspark

    oldspark Guest

  16. brenndatomu

    brenndatomu Minister of Fire

    Joined:
    Aug 21, 2013
    Messages:
    627
    Loc:
    NE Ohio
    And flue sized correctly for the stove...

    Insulation at the top and bottom only? That is kind of an interesting install, no?
  17. Woody Stover

    Woody Stover Minister of Fire

    Joined:
    Dec 25, 2010
    Messages:
    5,804
    Loc:
    Southern IN
    I gotta believe that the offset box is the culprit here.
    You can get the cheap snap-together black stove pipe at a farm store.

    You won't get as much draft as with a liner, but that's not the issue here.
  18. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    49,879
    Loc:
    South Puget Sound, WA
    Yes, grab a 3 or 4' length of 6" galv. lightweight venting duct, remove the cap and temporarily put it in crimp down. Secure so that it doesn't fall down and light the fire.
  19. oldspark

    oldspark Guest

    A correctly built chimney has a clay liner in it.
  20. Woody Stover

    Woody Stover Minister of Fire

    Joined:
    Dec 25, 2010
    Messages:
    5,804
    Loc:
    Southern IN
    True, but the clay liner is going to have a larger cross-section area, slowing the draft. And according to your previous post, dropping the flue gas temp will slow draft. So an insulated liner will definitely draft better than the clay....
    I don't know if he's got enough room in the clay liner to insulate his stainless liner, but that would have to help. I'm not sure how much it would help, though.
  21. Bluerubi

    Bluerubi Member

    Joined:
    Nov 26, 2012
    Messages:
    140
    Loc:
    Auburn, NH
  22. oldspark

    oldspark Guest

    Inside chimney so insulation may not be that big a deal.
    Chimney is on the short side a little height may be the most bang for the buck.
  23. oldspark

    oldspark Guest

    Getting side tracked here, they used to make a 7 and1/4 round clay liner and yu can go 25% larger with the liner size.
  24. oldspark

    oldspark Guest

  25. dafattkidd

    dafattkidd Minister of Fire

    Joined:
    Dec 11, 2007
    Messages:
    1,572
    Loc:
    Sound Beach, LINY
    So what if this does work? How do I connect a 4 foot section of Class A to a liner?

Share This Page