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Quest plus hopper fire

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by Neilt, Nov 29, 2013.

  1. stoveguy2esw

    stoveguy2esw Minister of Fire

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    continued;

    "starve/smother" a term i made up myself to describe what happens when fuel feed is interrupted long enough to cause the fire to drop to coals then feed resumes and the fire relights as the stove cools until it either warms back up or hits the low limit and shuts off. things that can cause this are usually associated with high draft air and low fuel feed (burning fuel faster than it is fed) however in a clean stove this usually doesn't result in much more than a dirty burn from constant relighting (think about how an igniter stove smolders to ignition, now imagine it doing that every several minutes) not a danger thing if dealt with in a reasonable time frame.

    now in a dirty stove this can cause a later more delayed re-ignition after the fuel has piled up much farther thus creating the "fuse" i referred to earlier.(remember when the fire dies the stove starts to cool and an ashed up heat exchanger will cool faster as ash insulates the remaining heat from the low limit switch, stove shuts off as its relighting and here we go with a smoldering fire under a connected fuel pathway.

    stoves equipped with vacuum interrupt switches for the feed system (usually designed to stop feed if either the draft motor stops or if the door or ash pan is unsealed) if they aren't able to be kept "satisfied" they will drop feed as well,
    here's the technical part of dropping vacuum due to resistance. temperature and air density are inversely proportional, hot air is lighter and therefore does not produce as much vacuum pressure at the same velocity as cold air does, so a restriction in the air pathway or in the vacuum port will allow feed at cooler temps but not at hotter ones, so the stove will feed until it drops vacuum, cool off then feed again. if the timing is right you can get a starve smother restart which can happen after the low limit is reached resulting in the same scenario.

    i could go on but it would get too boring for most to suffer through i suspect

    in closing folks, i didn't write this to scare people away from pellet stoves, i myself have for years gotten up in the morning and left for work with my family sleeping in their beds and my pellet stoves purring along. if that's not a ringing endorsement for these machines i cant do any better. a properly maintained pellet stove be it mine, or anyone else's made today (or within the last few decades like these old whits the OP has, are designed to prevent this issue from happening, unfortunately there is no foolproof method to "build" a burnback proof stove some may say there are some out there , i personally don't believe it with all due respect to the manufacturers of these units. the designers of Titanic said she was unsinkable as well. anything can happen under the right circumstances.

    BUT, the technology employed in these devices make it a rare occurrence and in most cases (not all, i wont say that) there is a maintenance issue involved. NOTE i am not blaming our OP for his incident i believe he has done his due diligence in that he has worked on trying to get this unit (a used one which he had no control over until recently) properly serviced to the best of his knowledge going in, we don't blame here we educate!

    bottom line folks, a well maintained pellet stove can be among the safest heating appliances available, even in a failure such as this , the fire cannot get out of a fastened steel box, smoke may get out which sucks, but with good smoke and CO detectors (i don't care what you heat with , GET THEM! maintain them test them and replace them when the manufacturer's posted lifespan is up) damage and injury can easily be averted. but folks we gotta maintain these units, read your manual contact your dealer or manufacturer if you are unsure of anything. inspect your gaskets regularly and replace them if suspect even if its before the manufacturers suggested replacement cycle hasn't been reached yet. dont forget the chimney! its just as important as the stove is.

    its as simple as this; a clean well maintained stove will be there for you when you need it, neglect your stove, and she'll let you down when you need her the most.

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  2. stellep

    stellep Member

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    Curious. What pellets were you burning at the time? Which smoke/co detector were you using?
  3. railfanron

    railfanron New Member

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    stoveguy2esw I thank you for your information on how this stuff works. I'm a newbie here and this information will prove very valuable to me as the amount of months using a pellet stove mount up.
    Ron
    becasunshine likes this.
  4. stoveguy2esw

    stoveguy2esw Minister of Fire

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    no prob Ron, and thanks,

    its my opinion that knowledge not shared is useless. places like this allow me to pass this information on, its really a great community, full of very talented people. im just one of many
  5. hyfire

    hyfire Feeling the Heat

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    Last edited: Nov 30, 2013
  6. ChandlerR

    ChandlerR Minister of Fire

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    I am always scared of a hopper fire, that is why I over clean my stove. Mike, thanks for the detailed explanations. I have always looked at my stove and pictured the airflow in my mind. One of the biggest *drafts*, if you will, is down the feed chute. You can see the flame being pushed away from the chute. You would think that because of this, I couldn't have a hopper fire, but there have been a few with my model stove, so as Mike says, it can happen under the right circumstances. I just have to make sure those circumstances don't happen.

    That said, if I ever had a hopper fire, would I ever feel comfortable running my stove again? Dunno....maybe not.
  7. hyfire

    hyfire Feeling the Heat

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    Not sure on all models, but on the erco-65 once it goes in to an error code it has to be reset manually, i.e. the vacuum switch tripping out or auger overtemperature. Is it common for other stoves to reset automatically?
  8. stoveguy2esw

    stoveguy2esw Minister of Fire

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    not too familiar with the countrysides, but if you are seeing air movement blowing down the drop chute look to see where its coming from, is the drop chute "inserted"? or is that feed system a welded in solid setup. we use the drop in type on the PAH (stove i run) and we silicone the area between the outer (welded in) drop chute , and the inserted chute which is welded to the feed tube to prevent this. if magnums are similar you would see air movement like this in between the inner and outer tubes of the drop chute. if you can find where this air is getting in and seal it off it would prevent that "blow forward" of the fire and bring it to a normal "curtain" effect which would be more desirable (might even keep your glass cleaner longer)
    IHATEPROPANE likes this.
  9. stoveguy2esw

    stoveguy2esw Minister of Fire

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    depends on the design, in our bottom feed units a primary vac loss kills the whole stove yet the top auger stoppage for the door switch just interrupts while the vac is lost and comes back when its remade no error. our top feed systems just drop and pick up with no error as well but it seems to work quite well as we've not had issues at all with burn backs in the top feed units and its extremely rare in the bottom feeders due to redundant systems to prevent it
  10. ChandlerR

    ChandlerR Minister of Fire

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    Mike, this may seem funny, but I liked the idea of air coming down the chute because it keeps the flame away from it. After reading your post, I looked and the chute seems to be a welded assembly which is bolted to the back of the chamber and sealed with silicone too. I always thought the airflow was coming from the hopper but now I'm going to look at it closely to see where else the air can be coming from. I just don't know where to look. I'm doing a cleaning tomorrow so I'll get my flashlight and see.
  11. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    Look where the drop chute joins to the auger/hopper assembly this is a prime spot for an air leak, as is the cover over the auger. Air can come in and down the chute. What is worse is that the same path can also be used to suck the flame (and other stuff) towards and up the chute. This reversed flow is apt to be the path taken when the vent system plugs up and the relative pressure differences are favorable. This same path exists at the bottom end of the auger flight once the pellet level gets too low in the hopper. More than one pellet stove manual cautions against letting the pellet level get too low.

    A bad set of seals in this portion of the fuel feed system can be the second failure needed to get pellets huffing and puffing in the hopper.

    Now some of these seals may be gaskets but frequently it is silicone or a good flat metal to metal fit.
  12. ChandlerR

    ChandlerR Minister of Fire

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    I will look at them tomorrow. I don't remember what the top of the drop chute looks like, but I'll check the auger bushing while I'm there. Who knew an innocent statement would uncover an issue? All that said, I will say that my glass stays clean and the stove throws some heat :)
  13. tjnamtiw

    tjnamtiw Minister of Fire

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    A quick 'butt-in'... Quads don't have sealed hoppers. :confused: Of course, they do have two snap disks on the pathway back to the hopper.
  14. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    Yeah, neither is mine, but the comment was for iceguy4's piece of mind as his is.

    Most hoppers are setup such that what happens in a burn back situation is nothing more than huffing and puffing smoke creation. Just don't open the lid.
    iceguy4 likes this.
  15. Madcodger

    Madcodger Guest

    First, very sorry to hear about the hopper fire. Scary stuff.

    I have an old Quest (not plus) that we bought for my basement office and installed this year after liking our Quad MVAE for the main floor for a few years but not wanting to spend that again for the office.

    After observing the flame and air flow carefully, I don't believe the draft that pushes the flame toward the glass is coming down the drop chute. Rather, I believe that it is coming up from the ash pan and into the firepot in that direction, by design. This may not be true for the Plus, but that's my observation of the original Quest.

    Personally, I am unable to run the Quest on any pellet feed rate lower than the line between Low and Med (7.4 seconds betwwen auger turns) because the fire will eventually go out (just not enough fuel to sustain it, regardless of damper setting). On one occasion of testing this, down to about 10+ seconds between turns, the pellets built up in the firebox with no flame showing and then reignited. Running at a higher feed rate has prevented this for us.

    I also find that the damper has only marginal effect, as noted. Low seems to just produce a lower quality flame without allowing for a pellet feed rate lower than that noted above, and anything above the Low-Med line burns well. Leaving it on the line between Med-High and making small adjustments to the pellet feed rate to control heat seems to work well.

    Just my observations based on a few weeks of observing a Quest.
  16. ChandlerR

    ChandlerR Minister of Fire

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    Ok, just finished my Sunday cleaning. Strip stove of fans, burn pot, and T cleanout. Vacuum everything, making sure the air passages are clean. While apart, I looked closely at the drop chute. I see it's screwed to the hopper and bolted to the burn chamber. Everything looks good. Auger bushings are good. I put everything together and hit the start button and used a long lighter to check for leaks around the auger and drop chute. Nothing. Lit the stove and put it in manual 5. I watched the flame closely and I think what I thought was air coming down the drop chute is actually coming out of the rear holes in the burn pot. Last year I had Mig welded some of the holes in the pot which made a huge difference in the quality of my burn but I think the increased airflow is making the flame more lively. So, I think I am in good shape. Thanks Smokey for making me think about this. I now know my auger and drop chute are in good shape! (And I have a wicked clean stove)
    SmokeyTheBear likes this.
  17. Neilt

    Neilt New Member

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    Everyone thanks you very much for the help. Stoveguy2, I'm almost positive that your starve/smother theory is very close.

    Stellep,
    I am burning North American pellets, kidde smoke and co (seperate not combo).

    So I cleaned the stove as best I could, and I ordered all new gaskets for it. However, I wanted to see what is going on with it. So I fired it up about an hour ago and watched it closely. Now before you comment on my trial here, lets make a few notes that my front door is 5 feet from the stove, I haven't left the room, I have water and an extinguisher readily available, my bunker gear is here, and I am a career firefighter. Also, both of the stores that carry Lennox products won't come look at this stove because they didnt sell or install it.

    This stove is by no means starving for air. As before, the draft is almost to strong. This unit has a manual damper and I still had it closed as much as possible. I did notice that it is barely getting enough pellets on the lower setting.

    I believe the stove all but went out due to a low feed rate, then the t-stat called for heat( high). The pot filled up with no ignition. It finally caught the pellets off the embers, and the pellets were piled up into the chute.

    Any other suggestions. Besides replacing the gaskets?
  18. Dgopetactical

    Dgopetactical Feeling the Heat

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    Hello,
    My stove does that "sorta" when I have the fuel feed on # 3 pellets pile and ignition is slow, if I accidentally start the stove on fuel feed 3 it will start after a wile then go out but still feeds pellets until the stove senses a problem and shutsdown. I do not have a stat. Other than that I can't help you with your issue mike knows best.

    You said in your post your a carrier FF, I would just like to say thank you!
  19. stoveguy2esw

    stoveguy2esw Minister of Fire

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    You said in your post your a carrier FF, I would just like to say thank you!

    if by "FF" you mean Fire Fighter, we are blessed by several of them. good on you to offer that thanks!

    i've been privileged in my careers (had a couple, long story) to have met some of the best and bravest of our species, many of those are firefighters. those who take the time to post their knowledge in here i count as friends, and i salute them as you did,

    with a simple, heartfelt "Thank You"
  20. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    You might want to see why you can't get full control of your draft, over time dampers can get deformed or the channel they sit in gets plugged on one end with crud preventing them from having full range of motion, some stoves also have other parts that get into the act by working their way against the damper because of normal cleaning or maintenance activity this also prevents full range of motion of the damper, then there is also corrosion wear of the damper, kind of hard controlling the draft with a none original hole in the damper.

    ETA: Also check your low limit system for proper operation, sometimes they stick closed thus not shutting the system down. Some of the Whits use a photo eye and frequently were known to shut the stove down when they shouldn't have because they couldn't see the flame due to scratches and crud on the lens in front of the photo cell. I have no idea of your stoves history but it wasn't unknown for safeties to have been bypassed or changed around. Also in this vein you might want to verify the closing temperature on any snap disc low limit is the correct value for the stove.
    Last edited: Dec 3, 2013
  21. Madcodger

    Madcodger Guest

    It might be especially helpful if other Quest / Quest Plus owners chime in re: their dampers.

    I know mine has an effect on temps I can achieve at a given pellet feed rate, but never closes down to the point I can set the pellet feed rate lower than the high end of Low. The combustion fan blows at a steady rate on these stoves, and there's just too much air to go below a certain feed rate. Any lower setting and there is insuffient fuel to sustain the fire for more than perhaps an hour. The flame goes out, but pellets continue to feed before the low limit switch shuts things down. Pellets could then reignite, which it sounds like happened here.

    In other words, one hypothesis to consider is that these stoves may simply be unable to be used below a certain feed rate, even if the damper is functioning at original specs or within some reasonable tolerance of that. I just haven't owned one long enough to know, as I never saw it operating originally. They're an "oldie but goodie" stove, but I wonder if the damper ever worked all that well at very low levels?
  22. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    I don't have a manual for that stove but tell me is there a set of trim controls for that stove, frequently stoves have trim controls that work only for low fire settings, some have others and some have none at all.
  23. Madcodger

    Madcodger Guest

    Thanks, Smokey. On Quest (not Plus) only controls are Damper (rotary knob that manually connects to damper via cable - turning it moves the cable, which physically moves the damper) and pellet feed rate (POT on the board). Also has high/low push button for distribution fan, start button, and auger on/off (which is how you turn off the stove - you just turn off its fuel supply). And that is IT. Nothing more precise...

    Don't know if damper knob is the trim you're referencing, but that's all that's offered. Rather imprecise, and I think the problem may be that it never closes to the point you can use the lowest feed settings,, and trying to do so opens up potential for a smother and reignite as happened here. Thus, solution MAY be to just not attempt that...
  24. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    Cable connections never did much for me. they can buckle and not move the item at the end of the cable, the cable end can slip through the device that is supposedly attached at the the far end thus moving the cable doesn't always move what it is supposed to.

    I've seen rod connections also fail or not be properly set up as well. I'm old, seen many strange things over the years.

    But that damper knob isn't the trim I'm talking about. Usually trims are electrical/electronic and hidden from general view and only set once when the stove is installed. On newer stoves the trims are usually in full view and somewhat explained in the manuals and the damper is only set at startup and there may not even be a control knob for the damper (It is hidden from view sort of the reverse of the older setups, wonder why?).
  25. bbone

    bbone Member

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    Neilt, where is highland ny? maybe I can give a 2nd opinion
    quest plus is simple stove, works well, needs cleaning often

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