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The Ultimate Overfire

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Jacklake2003, Jan 4, 2012.

  1. Jacklake2003

    Jacklake2003 Member

    Joined:
    Jan 3, 2012
    Messages:
    34
    Loc:
    Woodstock, GA
    Hello all, my name is Chris and this is my first post on this forum. I have a Napoleon 1401 insert that we use as supplemental heat in our home (since 2006).

    I've had a problem with the insert getting too hot for some time. The original fiber baffles that came with it barely lasted the first winter. I replaced with split fire bricks. This worked pretty well, but it was still really easy for it to overfire (650 deg. +). A few years ago I also modified the air control to allow the primary inlet to be almost completly covered. The stove heated great, I just couldn't/can't really load it up or it gets too hot.

    This year I purchased the new and approved baffles released by Napoleon as a "fix." They are a low-density cement-based baffles which are 2" thick. I also replaced the door gasket (again) to complete the maintenance. This helped considerably; the stove top cruises now at around 450.

    That was until last night. Confident that the stove was under control, I loaded it up with oak/hickory splits (split/covered for a full year), N/S, on top of a nice bed of glowing coals. I watched it for an hour with the draft only about 10% open. The flames were lazy; I would say starved for air if anything, but I just let it be thinking it would be a pretty "cool" burn. I have the normal Rutland thermometer sitting on the top/middle of the insert with one easy modification. I place a small sheet metal screw upside down (point sticking up)on the dial of the thermometer. The screw is so light that the dial easily pushes the screw along/around the face and of course the screw is left at the highest temperature.

    The scale of the thermometer goes to 850 deg.; It was past that this morning! The fire was long out and only a bed of coals left. The stove top temperature was down to only around 200.

    This really scared me and I'm at a loss of what too do. I could of closed the air control a little more (not much though) but than the fire probably would of been snuffed out/or would of burned for a long time at too low of temperatures. The fans were running on the stove at about 30%. The stove is connected to a 6" liner, straight up about 20-feet. The liner is in a factory-build fireplace/flu (Napoleon says this is OK) with tripple-walled pipe. The pipe is NOT insulated and it was cold (for Georgia) last night; about 20 degrees.

    Any thoughts? Thanks in advance for any input. -Chris

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  2. pen

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

    Joined:
    Aug 2, 2007
    Messages:
    7,228
    Loc:
    N.E. Penna
    I'm wondering if the problem is coming from covering the primary air. By reducing the amount of air that gets pulled in from that source by the draft, you'd be increasing the amount of air getting sucked in by the secondaries.

    I'd consider opening the primary air back up and trying it as it was designed again. If you are still having it get over 850 on you, I'd try to block a bit of the secondary air getting to the stove and see how you make out.

    BrotherBart shared a good link with me on this the other day that I think you'll be interested in reading. http://www.gulland.ca/florida_bungalow_syndrome.htm
  3. Huntindog1

    Huntindog1 Minister of Fire

    Joined:
    Dec 6, 2011
    Messages:
    1,556
    Loc:
    South Central Indiana
    I have had over heat for the following reasons.

    Over loading the stove especially with like all Oak and Hickory as they burn extra hot.

    Or Loading with to large and to hot bed of coals as this gets everything burning fast. As if all the wood catches at once on a very large bed of coals then too much heat is being generated and if the stove is fully loaded then heat is trapped from escaping as quickly leading to over heat condition.

    Or leaving the air open too long and letting heat to build up too much before shutting the air down.

    Loading North South lets the air get in between the logs more and fire burns faster and hotter.

    When I load East West and stack the wood high up in front of the stove in front of the door it causes the area up top in the back of the stove thats left around the burn tubes to be like a little burn chamber and it like traps heat back there from escaping towards the front of the stove under the baffle plate then forward up the flue.

    Some things to prevent this:

    Rake your coals forward all the way to the bottom, a little more work involved, also let your coals burn down more before loading makes raking the coals forward easier as its hard to get coals raked forward if you have too many coals. Your wanting to have the back half of the stove empty all the way to the bottom. Then load your wood East West in he back half all the way to the bottom and stack it up high as in my stove with 4" splits, they are almost square splits , I can stack 3 high if I raked the back half clean to the bottom. Now your ready for the second row of East West but most likely this second row will be sitting on coals and you will only be able to load 2 splits on top of each other pushed back against the back row. Then the front row you can load 1 split or put some kindling on the front row. Kindling if your stove heats up slow on reload Or just another medium split if you dont have heat up issues. I would not stack 2 splits high in front as it can lead to over heat condition.

    So what this hopefully gets you is your stove is burning from the front to back. The wood in the back is not going to burn for a while as its just sitting on the bottom of the stove and not on coals. Your dog house air is in the front and and things will start burning up front by the door. When I use kindling on that front row up by the door it burns hot and fast and gets the secondaries going quick but the main wood load in the back is mostly burning up on top up by the secondaries and on the front side of the wood towards the door. This setup keeps you from catching all your wood on fire at once and generating too much heat all at once.


    Lastly you can just load less wood as if the stove has more space in it then it will be harder to build up that much heat as these stoves tend to have trouble building heat when they are only partially loaded with wood.
  4. Jacklake2003

    Jacklake2003 Member

    Joined:
    Jan 3, 2012
    Messages:
    34
    Loc:
    Woodstock, GA
    Thanks for the replies! Pen, I wasn't entirely accurate in my description of the modification to the primary air inlet... the primary and secondary inlet is controlled by one lever. I adjusted the stop on this lever so it would push-in (close) farther. The result is that the inlet of the secondary was closed by the same amount as the primary. That being said, the secondary air inlet does appear to be a little larger and therefore more of the opening is exposed that the primary when the draft is all the way closed. Make sense?

    Either way, the Florida Bungalow Syndrome article is great! It precisely explains my condition and confirms what I've suspected. I just thought it was weird that my stove was burning so hot; I thought I was doing something wrong or maybe there was something wrong with the insert. I will now feel a little better about closing the draft all the way and I might continue doing small tweaks.

    When I was using fire bricks as a baffle, I experimented with different size air gaps in the front. I would "rip" different width bricks with my tile saw to achieve different air gaps. The results were dramatic. From hardly any draft with a wider brick to an out of control situation with a skinny brick. Unfortunately with the new baffles I purchased, I can't adjust this gap.

    Thanks again guys for the tips.
  5. kettensäge

    kettensäge Feeling the Heat

    Joined:
    Jan 18, 2011
    Messages:
    441
    Loc:
    N.E. PA.
    I think you need to be sure it actually over fired. Could the magnet or gravity move the screw rather than the thermometer pointer?

    Any other signs like discolored paint?
  6. HotCoals

    HotCoals Minister of Fire

    Joined:
    Oct 27, 2010
    Messages:
    3,355
    Loc:
    Rochester,Ny.
    What happens I think is that not charring the wood really well ,leaves a lot of moisture in the wood.

    It may take 2 or 3 hours on a long slow burn to get rid of a good part of that moisture.
    When most of the moisture is gone look out..high octane fuel is fed to your cat or tubes.
  7. Jacklake2003

    Jacklake2003 Member

    Joined:
    Jan 3, 2012
    Messages:
    34
    Loc:
    Woodstock, GA
    I don't think so. I've seen the needle at 800 before during the day after leaving the fire for a couple hours and returning. I put in 4 or 5 splits on a coal bed this evening and it's currently running at 600 with the draft fully closed (and that's closed more than factory due to my modification) and the blower on high. I think I'm going to work on closing the air inlets a little more.
  8. Burd

    Burd Feeling the Heat

    Joined:
    Feb 29, 2008
    Messages:
    410
    Loc:
    Bell bell Pa.
    I was having the same problem a few year back with my Napoleon 1402p. I was thinking about pulling the insert out to modify the primary. But after talking to some people on here years ago I got a few tricks. It doesnt matter if you load e/w n/s If you load that insert with temps above 400 its going to over fire. Its happened to me a lot intill I found the right Temp to reload (300 350) you have to find the right temp. The problem with this is that your not getting good heat out of the insert when you need it. Can you close your primary air all the way to snuff out the fire?( I wish I had that option) My2c Is that insert is a EPA stove and I dont think youll ever see temps above 900.
    Last night I wished I could have gotten the stove to over fire I couldnt Get the house above 70
  9. RIJEEP

    RIJEEP Member

    Joined:
    Oct 18, 2009
    Messages:
    61
    Loc:
    Lil' Rhody
    I've gained the most control and therefore confidence in my stove by examining the relationship between the 1) coal bed thickness, 2) reload stovetop temp, 3) weather outside i.e. humidity and temp, 4) properties of the reload wood going in the stove i.e. species (locust vs maple) and seasoning.

    These factors dictate the AMOUNT of wood and air I use to obtain a desired heat output.

    My biggest lesson in avoiding REALLY hot ST Temps was not reloading the stove when its too hot, or if i have to, definitely NOT using too much wood.

    Most of my lessons stem from a too cool or "uh-oh" too hot stove!

    If your problems persist the Gulland Associates Website hyperlink is a good read! The Bungalow issue is surprising indeed.
  10. robertmcw

    robertmcw Member

    Joined:
    Aug 27, 2008
    Messages:
    130
    Loc:
    Texas
    Lil’ Rhody – You can’t have said it better. When it is in the 30’s here, I must add wood about every 4 hours to keep the place warm and so the stove can cruise for a low in the 400’s to the 550’s temperatures on the stove. To reload, I add two splits (three if they are small). Too wood in and the stove (over three splits) the temperatures go up and I don’t like the stove to go over 600 to the 700’s. This year, I have pushed it once to 750 to red line it and I felt an ‘uh – oh’ moment and so I had to choke the air the kill the secondary’s and put the fan in high until it dropped back.

    Robert

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