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Harman P68... loss of power?

Discussion in 'Pellet Stoves, Pellet Fireplaces, Pellet Furnaces' started by gmbb, Jan 12, 2023.

  1. gmbb

    gmbb

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    Gentlemen; I have a p 68 and have a question on loss of power when the stove is in burning mode.

    Recently the stove was burning, probably a medium flame, and we lost power. I opened the stove door, scraped out the burning hot pellets into the ash pan below and all was well, it vented fine what smoke was left.

    I was wondering, if I was not home. Would or could the pellets continue to burn in the fire pot and then travel thru the auger and possibly cause the pellets in the hopper to ignite?
     
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  2. SmokeyTheBear

    SmokeyTheBear

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    While burn back has been known to happen it generally requires more than the one (loss of power) failure to happen. In fact your acts upon seeing the loss of power or far more alarming than the power loss. If the stove was properly installed and vented there is never a need to open the door except to clean. They are tested to be safe because of power loss and burn back. Please note the use of weasel words. BTW some of the best burners on here are ladies.
     
  3. gmbb

    gmbb

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    Why would moving the small amount of hot pellets into the ash bucket be alarming? I must have missed something. Essentially I did open the door and cleaned it of the burning pellets.
    Thank you
     
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  4. SmokeyTheBear

    SmokeyTheBear

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    burning pellets
     
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  5. scajjr2

    scajjr2

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    Get a small battery backup/UPS. That will let the exhaust fan cycle on-off until the stove cools down enough.
    If you open the door with no battery backup to keep the fan going you interrupt the draft and run the risk of smoke backing up and leaking.

    sam
     
  6. gmbb

    gmbb

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    ok, next time we lose power I will leave it alone and see what happens.

    Considering it sits on a metal plate on a concrete floor with nothing within 5 ft radius and a 8 foot ceiling I was not concerned with a cup or 2 of burning pellets or mainly hot coals. More concerned with 40 pounds of dry pellets inches away. As stated in the initial post, after closing the door the draft continued working fine.

    Sam; I will look into the battery UPS. Thank you
     
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  7. SmokeyTheBear

    SmokeyTheBear

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    Very few stoves have a lot of clearance and burning fuel is a bad thing without a forced draft most pellet stoves don't have enough of a draft to sustain a none feeding fuel fire and it quickly dies do to lack of oxygen. Opening the door feeds it plenty of oxygen, maybe. And opening the door can dump smoke into the house, maybe. Once again note the weasel words.
     
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  8. corncob

    corncob

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    Why I run 4" venting with a 15 foot vertical rise. Smoldering pellets is never an issue.
     
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  9. bogieb

    bogieb

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    For your concerns about burning back into the hopper - that is extremely unlikely. The pellets will burn up the exact same way they do when the stove is shutting itself down (you don't scrape the burning pellets out of the fire pot when it shuts down do you?) . No where in the manual does it say to go thru those steps you did, and the only concern they express is for smoke seepage.

    Burning pellets swept into the ash pan may cause them to smolder for hours. Ashes are a great insulator and that smoldering does nothing but create harmful gasses. Those are definitely something you don't want escaping into the room since you can't see them, you won't know it is there.

    As scajjr2 (sam) said, use a UPS that will allow the stove to shut down gracefully (not a pure sine wave UPS). I recently bought an APC850G2 to replace an old UPS. After charging it, I unplugged it while the stove was going and it went into shut down mode while pulsing the exhaust (which is what it is supposed to do).
     
  10. jtakeman

    jtakeman Moderator

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    Curious as to why not pure sign? Modified sign or PWM is rougher on electronics. Shaded pole motors get harmonic's and sound wierd(very annoying and rough on the motors, generates heat). Most stoves recommend pure as to not abuse them.
     
  11. imacman

    imacman

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    I wondered the same thing.
     
  12. gmbb

    gmbb

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    Thanks guys
     
  13. PelletHound

    PelletHound

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    The stove will continue to run normally with a pure sine wave until the battery dies.If the power has not been restored then the stove just stops.The non sine wave ups shuts the stove down by pulsing the combustion fan for about an hour or so.
     
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  14. corncob

    corncob

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    Have neither and don't need it. My 4" venting does just fine with smoke extraction.
     
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  15. SmokeyTheBear

    SmokeyTheBear

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    That would be the case if you wanted the stove to continue running B wants it to enter shutdown while sam wanted it to continue running. Two different thingys. The Harmans enter shutdown when they see other than a sine wave. Now read the fine manuals or believe the lady.
     
    Last edited: Jan 13, 2023
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  16. jtakeman

    jtakeman Moderator

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    :doh:
     
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  17. bogieb

    bogieb

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    Thanks to the Hound and the Bear, I don't have to do all that typing :yes:
     
  18. Harman Lover 007

    Harman Lover 007

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    Between the tight tolerance of the auger vs the auger tube and the fact Harmans have the slide plate at the bottom of the hopper, a back burn and hopper fire are extremely unlikely.
     
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