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)

How to extend your stove's burn times

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by precaud, Jan 2, 2011.

Thread Status:
Not open for further replies.
  1. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    29,123
    Loc:
    Northern Virginia
    I am not as concerned with the 30 about air washing the coal bed given the angle of the reburn tubes. I know that there has to be a lot of cooler air going up the pipe at the end of the burn though cooling off the stove and the pipe.

    Helpful Sponsor Ads!





  2. Battenkiller

    Battenkiller Minister of Fire

    Joined:
    Nov 26, 2009
    Messages:
    3,732
    Loc:
    Just Outside the Blue Line
    Depends.

    Depends?
  3. precaud

    precaud Minister of Fire

    Joined:
    Jan 20, 2006
    Messages:
    2,293
    Loc:
    Sunny New Mexico
    LMAO!!
  4. Battenkiller

    Battenkiller Minister of Fire

    Joined:
    Nov 26, 2009
    Messages:
    3,732
    Loc:
    Just Outside the Blue Line
    Precaud, this might solve some of the overfire situations that some folks get with exceptionally powerful draft. Yes, there are other purposes for this, didn't mean to sound disrespectful. I'm always interested in what you come up with, but I'll promise to stop playing Devil's advocate here if that offends.
  5. precaud

    precaud Minister of Fire

    Joined:
    Jan 20, 2006
    Messages:
    2,293
    Loc:
    Sunny New Mexico
    BK, busy work day, can't reply until later. Couldn't help but respond to your creative humor, though!
  6. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    49,786
    Loc:
    South Puget Sound, WA
    precaud, how many times have you spaced out reopening the secondary control? I suspect this would be a frequent problem in this house at least. If I made a mod like this I would want it done so that opening up the primary air all the way (like on startup) forced the secondary block to also open.
  7. NH_Wood

    NH_Wood Minister of Fire

    Joined:
    Dec 24, 2009
    Messages:
    2,602
    Loc:
    southern NH
    So I'm reading and thinking......how hard to remember to open back up???? Then, went to check the stove and the fresh load of cherry was just smoldering away - left the primary and pipe damper about 1/2 closed each - so.......you're onto something BeGreen! :lol: Cheers!
  8. precaud

    precaud Minister of Fire

    Joined:
    Jan 20, 2006
    Messages:
    2,293
    Loc:
    Sunny New Mexico
    Maybe a handful of times in 5+ years of using this, and all were caught almost immediately - the fire burns and looks VERY different without secondary air. I guess the analogy I would make is to a manual vs automatic transmission. Once your body gets into the habit of shifting and clutching, it just happens.

    I can see where that would be a consideration in some circumstances. Most stove designs aren't very accommodating to an interlock...
  9. precaud

    precaud Minister of Fire

    Joined:
    Jan 20, 2006
    Messages:
    2,293
    Loc:
    Sunny New Mexico
    That's an interesting point, BB. It begs the question, why does closing the secondary air extend the lifespan of the live coals? Or, how does "2ndary burn tube" air get to the coals in the first place? Why doesn't it just get pulled straight out to the chimney?

    I think the answer is: after the flames die, the 2ndary air gradually cools the parts of the stove that it contacts. At some point, the air coming out the tubes is cooler than the firebox temps, so it sinks right into the coals bed. Stoves that have more 2ndary air holes at the very back of the firebox will be more impacted by this. And that explains why the PE stoves and the Jotul F602 would benefit less from this; they both have very few 2ndary holes at the back. The F602 has none. After installing the 2ndary shutoff on that stove, I saw no significant improvement in extended coals life.
  10. Todd

    Todd Minister of Fire

    Joined:
    Nov 19, 2005
    Messages:
    9,226
    Loc:
    Lake Wissota
    I didn't think the secondary air tubes drew in air unless there were enough heat and gases requiring secondary combustion? After the fire dies down to coals is there enough draft to pull the secondary air up into the tubes or would it take an easier path through the primary?
  11. precaud

    precaud Minister of Fire

    Joined:
    Jan 20, 2006
    Messages:
    2,293
    Loc:
    Sunny New Mexico
    Sure is. If there's draft, there's secondary air being drawn. In many/most stoves there's more secondary air than primary under all conditions.
  12. dafattkidd

    dafattkidd Minister of Fire

    Joined:
    Dec 11, 2007
    Messages:
    1,568
    Loc:
    Sound Beach, LINY
    Precaud,

    Any idea how to do this on an Osburn 2400 insert? I'm installing one within the next few days and I figure if it's possible to do it, I may as well do it while installing it. I guess the question would be- Where is that whole located on the osburn? I'll figure out how to appropriately create a lever to operate it. (I doubt I'd actually do it, but while I have the thing in pieces I think it would be worth it to find out where this whole is) Thanks. This is an interesting thread.
  13. precaud

    precaud Minister of Fire

    Joined:
    Jan 20, 2006
    Messages:
    2,293
    Loc:
    Sunny New Mexico
    Kidd, yes, it's definitely best to do this mod before it's installed. I'm not familiar with this stove, so I can't point you right to the secondary air inlet. Like many stoves, the 2400 uses burn tubes attached to a common plenum (air channel), so you can just trace it back from the tubes to find the inlet(s). Many steel stoves will have the opening under the stove body.
  14. Battenkiller

    Battenkiller Minister of Fire

    Joined:
    Nov 26, 2009
    Messages:
    3,732
    Loc:
    Just Outside the Blue Line
    I'm confused. Isn't the air coming out of the tubes always cooler than the firebox temps? How could it possibly get hotter than the source that is heating it?
  15. precaud

    precaud Minister of Fire

    Joined:
    Jan 20, 2006
    Messages:
    2,293
    Loc:
    Sunny New Mexico
    That's probably a good assumption, BK. It's a matter of differential and velocity. And movement of air/gasses in the firebox. BTW, I don't view "firebox temps" as being one number.
  16. woodchip

    woodchip Minister of Fire

    Joined:
    Dec 6, 2010
    Messages:
    1,389
    Loc:
    Broadstone England
    The temperature in a flame will be much higher than the temperature near an air inlet, and the differing temperatures elsewhere will depend on the positioning of splits, shape of splits, and how much ash is under them.

    That's my take on temperatures within the firebox if it makes sense :)
  17. precaud

    precaud Minister of Fire

    Joined:
    Jan 20, 2006
    Messages:
    2,293
    Loc:
    Sunny New Mexico
    Sure, but it's easy to spin out on theoreticals - let's keep things in context - we're talking about what happens after the flames die...
  18. Jclout

    Jclout Member

    Joined:
    Oct 15, 2007
    Messages:
    149
    Loc:
    Southbridge, Massachusetts
    This really is a very interesting thread as I am trying to extend burn time on my Quadrafire 3100. I took the right side panel off to check out the air intakes for the stove. I also talked to my dealer about how the primary intake effects the secondary air. As the primary is opened the vacuum (when the panel is on) becomes stronger and draws more air into the burn tubes. The burn tube ends are covered by a rectangular box with a hole in the bottom, this is the only inlet for air into the tubes. I'm thinking of keeping the side panel off and using a high temp magnet to cover the hole as an air adjustment. Leaving the panel off also reveals that the primary inlet is never completely closed, the hole is too big for the cover, so I would like to be able to cover most of the rest of the opening with another magnet but still leave a bleed hole. When the outgassing has stopped I can close the secondary hopefully keeping the coals alive longer and cover up most of the primary hole that's left over all in the hopes of increasing burn time if I am following this thread correctly. There also are third and fourth air intakes for the stove visible when the panel is off. The automatic timer or startup air is one and another is an oppening to the rear air channel. However both of these opennings are ether opened or closed because they both use a round gasket on a hinge instead of something sliding across them to cover or uncover the holes. I guess you can get the round gaskets very close to the hole to create a sliver of an opening but basically its all or nothing. What do you guys think?
  19. Jclout

    Jclout Member

    Joined:
    Oct 15, 2007
    Messages:
    149
    Loc:
    Southbridge, Massachusetts
    I forgot to mention that the primary air is also the air wash system for the glass. Are most other air wash systems also the primary air?
  20. woodchip

    woodchip Minister of Fire

    Joined:
    Dec 6, 2010
    Messages:
    1,389
    Loc:
    Broadstone England
    Mine is so I assume others have similar designs Th primary air keeps glass clean, and secondary is prewarmed and comes through small inlets along the baffle which gets the secondary combustion (of what would otherwise be wasted burnable gas going up the flue).
  21. Jclout

    Jclout Member

    Joined:
    Oct 15, 2007
    Messages:
    149
    Loc:
    Southbridge, Massachusetts
    woodchip, nice to have a wife that likes collecting wood huh!
  22. woodchip

    woodchip Minister of Fire

    Joined:
    Dec 6, 2010
    Messages:
    1,389
    Loc:
    Broadstone England
    I suspect she prefers the sitting being warm and cosy by the fire bit more, but one tends to lead to the other ;-)
  23. OhioBurner©

    OhioBurner© Minister of Fire

    Joined:
    Aug 20, 2010
    Messages:
    951
    Loc:
    Central Ohio
    I blocked the zipper air on my Rockland and that seemed to help extend the coals quite it bit.

    Does anyone know where the secondary air port is on a Jotul Rockland? I dont remember there being any visible holes on the outside anywhere.
  24. Jclout

    Jclout Member

    Joined:
    Oct 15, 2007
    Messages:
    149
    Loc:
    Southbridge, Massachusetts
    Ohioburner what is the zipper air on your stove? I've never heard that before.
  25. OhioBurner©

    OhioBurner© Minister of Fire

    Joined:
    Aug 20, 2010
    Messages:
    951
    Loc:
    Central Ohio
    In the bottom of the inside of the stove in the middle there is a buldge with two air holes that feed air into the coal bed to burn the coals down better. Folks here have tapped the holes and then inserted a bolt into them.

    If its keeping coals your interested in I'd start with that since that is what it is there for and worry about secondary air next. I dont have any clue what other stoves have it but both my Jotul and my Hearthstone do.
Thread Status:
Not open for further replies.

Share This Page