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Stove still starved for air

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by dave11, Oct 12, 2009.

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  1. dave11

    dave11 Minister of Fire

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    I posted here a couple weeks ago about my new Englander 30-NC installed in a walkout basement. The fire died out when the door was closed, but roared if the door was open just a crack. Got a lot of good advice and made some changes, with some improvement, but still doesn't seem right.

    The stove sits on a nine inch pedestal in the basement area, with a two foot vertical run, then 2 45 degree elbows going to horizontal, then a two foot horizontal run, then a 90 degree elbow going upward. It's about 23 feet from there to the top of the chimney.

    Fire starts fine, and roars away, as long as the door is cracked open just a hair. The stove air inlet is fully open. Temps on the stove range from 450-520, and temp at the pipe entrance to the wall is between 250-300. The fan is off.

    Now, if I seal the door, the fire continues, but gradually fades to wispy blue flames. The red coals at the bottom keep burning bright red. The temps though drop on the stove to about 350, and the pipe at the wall drops to 225.

    I've never used a woodstove before, but to me that doesn't sound right. The temps are too low to keep creosote from forming in the liner, correct?

    Lots of past advice centered on the flue draft perhaps being too low, but I still don't understand why cracking the stove door open just a bit would change the flue draft and make a difference. And I don't see why the flue draft should be a problem. The install essentially mimics the install shown in the manual.

    Thanks for any any advice.

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  2. Jags

    Jags Moderate Moderator Staff Member

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    If I remember your prior post properly, (which is not guaranteed) , you defended your wood as "dry". Do you KNOW FOR A FACT that you have properly seasoned wood?
  3. ControlFreak

    ControlFreak Feeling the Heat

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    Listen to what Jags says. Moisture content in the wood is the #1 problem for newbies (and oldbies). Also, be aware that you will always see a huge change when you close the door. That's normal, but the fire should recover after a little while. When I'm lighting a new fire I often close my door in stages so the fire adapts without a big disruption. A fire is a delicate process and when you make radical change to its environment, you will create a visible disruption, and sometimes entirely extinguish a flame. If that happens, then you want to let the fire get a little hotter, or close the door and leave a tiny crack as the fire adapts. If your wood has high moisture content then it just won't burn with the door closed no matter what you do. Get some wood that you know for sure is crispy dry and see how it goes with that.

    The first year I had my stove I went through the same thing with unseasoned wood.
  4. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    Not to insult, but do you have the air control rod pulled "out" toward you when you close the door?
  5. drdoct

    drdoct Feeling the Heat

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    LOL BB, that's exactly what I was thinking... Has he tried the air in another postition? It's either wood or you've got the air control mixed up or somehow clogged.
  6. dave11

    dave11 Minister of Fire

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    I did consider that early on, and even now, in a paranoid way, I keep trying to pull it out farther.

    But yes, the air control rod is fully out, as specified in the manual. It does make a difference, because when I push it in ,the flames die further.
  7. dave11

    dave11 Minister of Fire

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    I have a good quality moisture meter, and it reads 17-20% depending on the piece of wood.
  8. Jags

    Jags Moderate Moderator Staff Member

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    And I am going to assume that you re-split the wood and tested on the newly exposed area?

    That being true, then you are plugged up - somehow. Intake is probably where I would start.
  9. dave11

    dave11 Minister of Fire

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    As I mentioned, the fire does keep burning with the door sealed, but i'm worried about the temps. Shouldn't the temp at the pipe at the wall be close to 250 degrees? That's as high as I can get it with the door closed.
  10. dave11

    dave11 Minister of Fire

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    Yes. I do a lot of woodworking, so I learned early the proper way to test wood for moisture. Plus, the wood has been sitting for two years in a shed with ventilation, but totally protected from rain/snow.

    A lot of it looks like poplar, which I know burns with less heat, but is that enough to make the difference?
  11. Jags

    Jags Moderate Moderator Staff Member

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    Is this single wall pipe surface temps?? If so, you should double your number for internal temps. (250 surface = 500 internal) which is acceptable.

    By your description you have one of two problems.

    1.) fuel that is not suitable to burn
    2.) lack of oxygen to support the burn

    Now if you are ruling out fuel, that leaves number 2. If the door cracked open gives you a "roaring" fire, my guess is that your flu is open to the outside. When you close the door your flame dies out and temps drop, even at the highest (most open) air setting. That tells me lack of oxygen. Start with the air feeding the system and move up.

    Things to look for:
    Blockage of any air intake holes.
    Lack of draft (maybe the flu is too short)
    Negative air pressure in home. Do you ever get smoke spillage into the living area?? Do you have other appliances fighting for air (exhaust fan in bath, power vent appliances, etc.)

    Edit: burning poplar and pine is blamed for many things. Lack of heat ain't one of them.
  12. Todd

    Todd Minister of Fire

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    Do you have a chimney cap? If so try burning the stove with the cap removed and see if that helps, some of those caps can really restrict the flow.
  13. dave11

    dave11 Minister of Fire

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    Yes, it is single wall pipe. So the actual flue gas number is double the surface temp? That makes me feel a lot better.

    I will try wood from a different stack next time, just to see if it makes any difference. I don't think neg pressure is the problem, because opening a nearby window at ground level makes no difference, and I've never had smoke spillage, even with a cold flue. The house is old and the basement still somewhat leaky.

    My take on this from the beginning is that, by design or by accident, the air intake on this stove is too restrictive. I tried running a long wire through the air intake as far as I could but couldn't feel a restriction or blockage. Unfortunately, according to Englander, there is no way to access the air passages to see for sure.

    Maybe I will always need the door cracked open, though I bet this negates the air-wash system.
  14. Jags

    Jags Moderate Moderator Staff Member

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    No, no, no. Don't do that. Its gonna negate alot of things, like control, clean burn, operating temp, etc.

    Lets revisit the draft issue. Todd had a good idea with the cap. What is the total length of VERTICAL pipe??

    Oh, and yes, surface temp of a single wall has to be doubled to approximate the internal temp.

    Edit: hey - does anybody remember off the top of their head the trade off of a 90 degree pipe has? Its something like a 90 deg pipe equals reducing the overall length by xx feet.
  15. dave11

    dave11 Minister of Fire

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    I believe in the last post about this I was told each 90 degree elbow subtracts 5 feet.

    The total vertical run, as close as I can estimate it's 20 feet from ground level to the top of the chimney, and the stove sits 6 feet below ground level, so 26 feet total. There is one 90 degree in the wall, and two 45 degrees together making the turn to horizontal coming out of the stove.
  16. dave11

    dave11 Minister of Fire

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    There is a cap, installed with the SS liner. Can you leave the liner open to the sky? Or do you mean to try a different type of cap?
  17. Jags

    Jags Moderate Moderator Staff Member

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    Thats what I was thinking as well. So you take 26 - 5 = 21. Now you have 2 45 deg as well, lets call it 3 feet worth. 21-3= 18. Now you have a horizontal run, that also inhibits the draft, lets say another 3 feet worth. 18-3=15. You are now at about the minimum for stack length. Add on ANY other factor ( like the cap, neg air pressure, clogged air intake, etc.) and your in a very tough position.

    If you want to test my theory, go to the hardware store and buy a piece of the cheap heating duct (just for giggles go with like a 5 foot section) and mount it on top of your existing pipe. Light a fire and see what happens. For a couple of bucks you may find your issue.
  18. dave11

    dave11 Minister of Fire

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    Interesting idea. It would take some doing though to test it because the chimney is hard to access. The power lines to the house cross right through the only area where a ladder can be placed to get at the top of the chimney. In fact, when the liner was installed, the sweep's helper had to climb the ladder placed on the other side, then stand on top of the chimney to work. Can't stand on the roof without special equipment because it's clay tile (and fairly steep).

    I thought the install would be fine though because it is essentially what is described in the install manual, where in fact they show two 90 degree elbows that are sharp, whereas I've replaced one elbow with 2 45 degree ones.

    I'm still not sure how for certain this can be a draft issue. If the flue is somehow too restrictive, why would opening the door accomplish anything at all? The flue isn't made any wider or taller or straighter by opening the door. If the fire roars with the door open just a crack, how can there be anything wrong with the flue?
  19. kenny chaos

    kenny chaos Minister of Fire

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    I have an equivalent stove and sometimes she just doesn't want to put out.
    I posted about it last fall (first time with this stove) and got all the same good advice.
    Nothing helped though.
    It's dead calm today and I can barely keep the stove top at 300 degrees.
    If I had the old smoker going, it would be one of those days when the back fields would have a heavy layer of smoke laying down over them.
    I don't know if it's barometric pressure or what.
    When it gets really cold, she runs fine.
    Open door helps and while it doesn't peter totally out, she dies down a lot with it closed.
    Still burning clean (no smoke out the chimney).

    Summary: I don't worry about it. It's burning clean, not killing us with too much heat, and really comes on when it counts.
  20. kenny chaos

    kenny chaos Minister of Fire

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    Here's what my people told me;

    "My thought is that when atmospheric conditions support rising or high barometric (atmospheric) pressure, there is actually a tendency for sinking of the atmospheric column in the area (actually referred to a "subsidence"); this sinking of the air column would be less supportive of the smoke from the wood burning stove being able to rise upwards and outwards through the chimney or exhaust piping, thus maintaining more of a smokey odor. Such conditions do develop after a weather change and can be enhanced at night when the winds in the low-levels of the atmosphere become light or calm, while the overall subsidence process in the atmospheric column continues."
  21. kenny chaos

    kenny chaos Minister of Fire

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    One more thing: As I'm writing these entries, my fire is petering out.
    The wife just drove home from the city and I told her about our struggling fire and this post and she stated that
    she in fact did see smoke hanging on the ground.
    So cheer up!
    Probaly nothing wrong with your stove.
    Just one of those things, or not.
  22. Jags

    Jags Moderate Moderator Staff Member

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    Kenny could be on to something (and by that I am talking about little pink pills. ;-P ). But really, there is truth in his words. If that is the case - a stronger draft could only help. Adding 5ft on to your stack WILL create a stronger draft. I am in no way saying that this is going to cure your issue. Just stating that it is an option.
  23. kenny chaos

    kenny chaos Minister of Fire

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    Pink pills? The only thrill I get any more is from pink, strawberry flavored fiber tablets. I'm surprised you'd bring that up. :bug:
  24. Backwoods Savage

    Backwoods Savage Minister of Fire

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    On the elbow issue, 2-45 degree elbows still equal 1-90 degree elbow. I also think each elbow requires an additional 3 feet of chimney rather than 5 feet.

    On the draft and having the fire door open, many people do this when starting a fire with a cold stove and chimney. I even do it. All it does is feed extra oxygen to the fire to get it going faster. And I'll also bet that most folks from time to time have the same issue as you have....but not as extreme.

    Check me if I am wrong fellas but also having the stove in the basement brings in a different situation than if it is not in the basement. Something about air pressure?
  25. pen

    pen There are some who call me...mod. Staff Member

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    I have looked back through the post and didn't see where you stated the Inside Diameter of your chimney. Your stove is a 5.5-6inch exit. Is your chimney a 5.5 or 6 inch chimney? If the chimney is a larger diameter than 6 inches that can be your source of the lost draft since the air cools as it goes from a 6in pipe w/ a cross sectional area of 37.68 to 50.24 sq inches for an 8in pipe.

    pen
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