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EPA stove newbie - secondary combustion and operation Q

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by XJma, Nov 6, 2012.

  1. XJma

    XJma Member

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    Finally got our wood stove insert installed in our cape a few months ago after wanting one since we bought it. Both the wife and I grew up with 'regular' or old school wood stoves, i.e. damper up top and air on bottom, so we're not total greenhorns when it comes to running wood stoves. I think we're getting the hang of it pretty well but we're far from being experts at this thing as of yet, obviously. We have about 2 cords of fairly dry wood, and a half of 5-6 year dry wood, and lots of green. Wish I had really gotten on top of getting more dry wood earlier, but the battle has begun! Doing lots of great reading here and getting tons of invaluable info, thanx!


    Anyways, I've searched and can't quite seem to get a straight answer about two things. First, wide open, 'throttle' or air control all the way in, is this the equivalent of running an old school stove with the damper open?? I understand more air when all in and less when all the way out, but what is the relationship of the damper (if this stove has a comparable part) and the air control? Does the damper close when the air control is pulled out just a hair? Or is it not quite that simple?? Wish I could find a good diagram of my Avalon Rainier or any similar stove with explanation of operation, etc.

    Second Q, secondary burn. I found a video on youtube of a guy cranking his rainier wide open and then pulling the lever all the way out, at which point the flames on the logs die down and flames in the firebox shoot out of the tubes, red, orange, and blue. I can reproduce this, but can't keep it going with pure flame in the air and none on the logs for very long....again, bulk of what I'm burning is moderately well seasoned but not bone dry, no MM, yet. Basically, am I only getting secondary burn when I pull the throttle all the way out?? What about when I have it cruising at 350-650 F stove top temps (magnetic thermo verified with infrared thermo)? I see flames dancing around the tubes, but not always all over the tubes and not always blue. I can go outside and see shimmering heat coming out of the chimney and very little to no smoke. Doesn't this mean that I'm both losing heat up the pipe and getting secondary burn (even though I don't necessarily see it)???

    Thanx for reading my long post and thank you in advance for your help!!

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  2. corey21

    corey21 Minister of Fire

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    Welcome.

    I will tell you those youtube videos are for show.

    Congrats about have good dry wood.

    I get most secondary combustion with my air closed or a bit open With the air open to full you are sending a lot of heat up your pipe. Try getting it to 400 stove top then close it down in stages depending on you draft will determine your final air setting.

    Hope that helps.
  3. Swedishchef

    Swedishchef Minister of Fire

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    Welcome to the forums!

    Glad to hear you have some dry wood. Now start cutting/splitting and stacking asap for next winter and the winter after that! EPA stoves need dry wood to burn properly. Otherwise you will be disapointed and frustrated (trust me on that...it happened to me my first year).

    EPA stoves are very different from old smoke dragons. Usually there is no need for a pipe damper. The primary air control is able to "control" the amount of oxygen entering the combustion chamber thus allowing for a higher or lower rate of combustion of the wood.

    I guess you could consider an air control fully open to be the equivalent to opening a damper on an old school stove. Leaving the primary air wide open allows for more oxygen to enter the combustion chamber and help get your fire going. I believe on the Rainier pushing "in" your rod will fully open the air. Pulling it out will close it. (http://avalonfirestyles.com/TravisDocs/100-01140.pdf)

    Secondary burn is easy enough to explain: First of all, when wood begins to heat up it will off-gas. In EPA stoves there are secondary air intakes that pass air through secondary burn tubes normally located on the top of the combustion chamber. When your combution chamber temperatures get high enough and the off-gasing of the wood comes in contact with this secondary air, the gases will ignite and cause those types of flames you saw on the youtube video.

    When your primary air is open and the fire is rolling with a good (400-500F) stove top temp, start closing down the primary air in stages. This will force more oxygen into the combustion chamber via secondary air intakes and will help provide a clean burn. I can't close my primary all the way on my stove, it will snuff out the fire. I usually leave it open 1/8th of the way.

    When you look at your chimney and you only see vapour waves, you're going in the right direction! Do you have a thermometer on your stove pipe? I usually have mine going between 400-500 for 1-2 hours or so. OFf-gassing will cease soon enough and you won't have secondaries for much longer (at least not in my experience..they usually last 30mins-1.5 hours depending on amount and type of wood loaded into the stove).

    Keep your chin up and happy burning!

    Andrew
  4. XJma

    XJma Member

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    So if I understand this correctly, no damper at all?? Interesting. I need to see an exploded view of how this thing works! I guess they do have an EPA stove with a big chunk cut out of it at the place I bought the stove..... And yes, lever pushed in is wide open, out is choked. So all this does is control intake air....crazy!

    And so the secondary burn, not something that happens during a normal burn? Something that is difficult or at least takes a little skill to achieve and only lasts for so long? I was kind of under the impression that the stove would do some secondary burning during most of the burn time as it's got some low emissions ratings or some such thing?? Also, I have it setup as a fireplace insert with the surround and the blower, so the stove top temp is on the very front edge of the top that sticks out past the surround, and is angled slightly down. air front the blower comes down right on top of it too....not sure if it's possible to rig up a thermometer on the stove pipe?? Wish I was home when they installed it, but I wasn't :(.


    Thank you for the help!! And I have some decent wood, not great wood, and not enough! Wish I had acquired more wood, but tough to find the time/motivation to process and stack wood before you even own a wood stove! In the process of becoming a hoarder myself :)
  5. XJma

    XJma Member

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    Wait, so with the air open it is like I have a damper on the pipe and have it open? It feels like the air control at certain points may engage/disengage certain other internals within the stove....I need a diagram! The manual doesn't get specific enough for a tech junkie like myself.

    I assume I have pretty good draft, I can hear whistling whether the stove is on or not with the door closed and it's masonry chimney in the center of our cape.

    So running it wide open is not going to be distributing much heat throughout the house, right?
  6. Swedishchef

    Swedishchef Minister of Fire

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    The primary air sort of acts like a damper used to on an old stove. It controls the amount of air you let into the stove for combustion, therefore, how much the fire is "roaring".

    Secondary burn does occur during a normal burn. It is part of the combustion process in an EPA stove if you operate it properly with good wood. Secondary burn is simply a phase that occurs during a burn cycle of a load of wood.

    I am uncertain if you can rig a thermometer on an insert liner...someone may chime in and be able to provide a better answer than me. LOL.

    HEre is a link/video that explains secondary burn...

    Even if you turn down the primary air, you will still get a lot of heat because the secondaries will heat up the stove top quite well.

    Andrew
    XJma likes this.
  7. XJma

    XJma Member

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    Thanx again Andrew, I'm starting to get a better understanding!! That video was very helpful...the internal shots of that stove look exactly like mine. I'm glad that secondary happens to some degree during a normal burn cycle!!

    Needless to say I spent a lot of time last night playing with the damper! Some positions make the heat go down but it seems like 1/16" of a difference or so can make the heat increase. I guess practice makes perfect (or at least better), right?
  8. begreen

    begreen Mooderator Staff Member

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    You want to close down the air in increments. Each time close it down until the flames start to get lazy. The let it burn like that for about 5-10 minutes. When the fire pick up in intensity, close it down more until the flames get lazy again. Ideally you want a lazy fire with the secondaries wafting occasionally over the top of the wood. A raging fire and secondary show is mesmerizing, but a bit wasteful of wood.
  9. XJma

    XJma Member

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    Thanx begreen, I was starting to get that idea playing with the fire late into last night. Guess what I'll be doing all night tonight too??

    Also, are the high winds going to mess with my game? Another storm on it's way, yeah!
  10. corey21

    corey21 Minister of Fire

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    The high winds will cause too much draft or down drafts
  11. begreen

    begreen Mooderator Staff Member

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    If this is your first time burning and the winds are very strong, you might want to wait a day for it to pass. It would probably be fine, but it does take a calm head if you suddenly get a downdraft and a room full of smoke. I'm not saying this will happen, just that there is the potential for something like this if the winds are very strong gusts. If the winds are strong but steady, there is the potential for having much stronger draft than you are used to. That can lead to an overfire under the right conditions. Again, this might not happen for your installation. There are a lot of variables at work, like fire size, flue height, flue location, house location, etc.. If you are unsure, I'd go back to the central heating for a day or two or at least build half full fires and don't try to go all out.
  12. Swedishchef

    Swedishchef Minister of Fire

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    LIke Corey said, depending on where you live/your terrain setup, high winds can create a downdraft (hard to start a fire without smoking coming in) or increase your draft. In my situation, it increases the draft significantly. That means I turn down the air even more for a cruising fire as the wind "pulls" air into the stove by creating a vacuum at the chimney.

    As BeGreen mention, always wait 5-10 minutes after an adjustment to see the results. A change in damper won't create an instantaneous change, it will take a few minutes.

    Andrew
  13. corey21

    corey21 Minister of Fire

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    I am with begreen might want wait a day or too.

    During Sandy my stove stayed at 700 for a while i don't normally go that high.

    Edit. But i kept a cool head cause i know that nothing was glowing.
  14. XJma

    XJma Member

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    I have a center chimney in a cape, and in a relatively flat area, open yard is an old pasture with trees separating neighbors who have even larger open pastures.

    I guess I'm not really afraid of a down-draft...if I can't get it going I can't get it going. So basically, don't be surprised if it runs hot on full choke?
  15. corey21

    corey21 Minister of Fire

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    I guess I'm not really afraid of a down-draft...if I can't get it going I can't get it going. So basically, don't be surprised if it runs hot on full choke?[/quote]

    After having a down draft in my shop stove i am more scared of down draft then running a little hot smoke started puffing out of that stove air vent not good.

    But every setup is different have not had down draft in the mag yet.

    Just be watchful more then usual running the stove in windy conditions.
  16. XJma

    XJma Member

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    Oh, so the downdraft is not only with the door open?? What kind of conditions (other than high wind) would cause one? Is is more likely with a cold flue?
  17. eclecticcottage

    eclecticcottage Minister of Fire

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    We have most of our pipe inside with 5 or so feet outside. We sit between cornfields and the lake, so we get hit by winds pretty regularly. We've found it increases draft like crazy, although it depends on wind direction as to how much. At one point last year we had fairly high winds that hit from just the right direction, the draft was sucking the fire right up the stack, it was pretty wild. Usually we don't get that crazy, just burn more wood quicker. So, we keep it in mind and run smaller loads with the air choked in *IF* you choose to use your stove (insert). Watch how much you choke the air, too much can help cause a down draft though. Our stove is it for heat here so if it's cold and windy, it's running no matter what.
  18. begreen

    begreen Mooderator Staff Member

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    With strong gust and squirrely winds, expect the unexpected.
  19. bag of hammers

    bag of hammers Minister of Fire

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    I have recently been able to close the primary air off completely for an overnight burn. Just as begreen described it, the fire was "lazy" with some nice secondary flames dancing around. I think I just happened to hit the perfect conditions - wood, outside temp, etc. This isn't typical for me - I've usually been leaving the primary air open a tiny bit on the overnight burns but I guess all the variables just lined up that night so I let it run like that and got the best (longest) overnight burn so far. As mentioned, shut it down in stages, and watch how the fire reacts each time. You will find the sweet spot for your setup. It still may turn out to be just a bit of a moving target (e.g. you throw in a couple splits of well seasoned wood with one that's a bit green, and you adjust a bit). But that's half the fun / experience IMHO.
  20. XJma

    XJma Member

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    Well I've been applying a little bit of my new knowledge tonight and even with the high wind gusts I've had this stove cruising with a good amount of visible secondary burn for up to about an hour and a half with just minor adjustment tonight. Have had it choked way more than normally, I guess due to the increased draft. With a little bit of delay after each strong gust the flames pick up for a little bit. Having lots of fun :cool:
  21. Swedishchef

    Swedishchef Minister of Fire

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    Glad to hear things are going well..my stove will be lit in the am!!
  22. corey21

    corey21 Minister of Fire

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    Glad it worked out.

    Had to let my fire go out tonight got up to 83 in here.
  23. XJma

    XJma Member

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    Nice and hot here in the living room, trying to get heat to go upstair....old cape, grrr. Stove pumping out tons of heat. No way I'm letting the fire go out during the first accumulation of the year! Prospects for a great ice season are looking good!
  24. hatting9

    hatting9 New Member

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    Will a crack in the secondary burn tube keep the tube from working properly?

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