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25-PDV low air burn/low fuel feed question

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by biohill, Jan 19, 2008.

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  1. biohill

    biohill Member

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    My stove is hooked up to a thermostat, but it was never kicking on because the stovewas cooking me of my house (only 1100sq ft) on a setting of one. I changed the low fuel feed down to a three and the low air burn to a seven. It has burned fine for a week or so and cycles back and forth between the low setting and setting five just fine. Is there any reason why I shouldn't have it set this way? Thanks for any info.

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  2. bret4

    bret4 New Member

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    I've been messing around a little with those settings too. I guess as long as the fire keeps burning and it doesn't make the stove too dirty it should be ok. Wonder what your stoves factory settings were? My factory settings were 6 4 1. I'm running 5 5 1 right now.
  3. blanc12

    blanc12 Member

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    If the fire isn't going out and you are not getting clinkers those settings should be fine. If it is too warm when the stove is running low, when the thermostat is not calling for heat you might want to close the restrictor plate in the hopper some more. Just remove the pellets from the hopper and loosen the screw on the plate. move it forward some to close the gap to the top auger. this will slow down the feed some.

    Hope it works out.
  4. stoveguy2esw

    stoveguy2esw Minister of Fire

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    big thing to look at is that when you adjust these settings , for starters remember (as in write down) what they were at first so you can reset them if necessary. then as you adjust the low fuel feed down , do it gradually with the stove running on a heat range of 1 and out of startup. if you adjust too far down , the stove will extinguish and relight with each batch that comes in , this is a big "no-no as it will burn very dirty and soot the pipes rapidly , if this happens raise the LFF 1 notch and stay there.
  5. bret4

    bret4 New Member

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    Hey Mike,

    Just wondering about the factory settings. My settings were 6, 4, 1. I'm sure a lot of testing must have went into coming up with those numbers. Do they come up with these numbers burning some average pellet type or the poorest burning pellet we might find to burn in our stoves?

    Another question is, would it be better to adjust the restrictor plate to get a longer burn time on low when using a wall thermostat than adjusting the factory numbers?
  6. stoveguy2esw

    stoveguy2esw Minister of Fire

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    bret, it varies, depends a lot on the physical size of the pellets themselves. the numbers we set are basically a "high of middle of the road" set , that should keep the stove from going out no matter how big the pellets are as long as they conform to PFI standard. the note about not messing with them came as a decision not to just publish the way they work as to avoid customers blindly customizing settings without guidance ,getting them too far off in the wrong direction can cause some pretty ugly burns. i prefer to have an idea based on burn times and a few descriptive answers to advise what the "dialing in" method should be , remember pellets even though they all have the same standards do vary , as does climate , elevation and other things, so what works in golden colorado , may not in dover delaware.

    adjusting the slide plate will affect the stove on all heat ranges, the trim settings only will effect the burn on the low setting , not on the high setting, again its going to fall under what you want the unit to do. if you want to only slow the low side , and leave the high alone , use the trim buttons , but if the high is in need of trimming as well, use the slide plate , note however that lowering the trim as well as closing the slide plate could lower the low side too much causing a loss of flame when the stove reverts to low burn.

    if you want to find out more detailed info , get in contact with me either by pming me a daytime phone number where i can call you , or contacting my shop for this info. be happy to explain it out in detail to you , but to do it completely in here would take a lot of typing and a lot of space
  7. bret4

    bret4 New Member

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    That's interseting Mike. One day I will have to get on the phone with you and get more info on how I can fine tune it a bit. For now I am having fun trying things out with small adjustments to see what it does. So far I am seeing that the Factory settings are not bad and I may just end up back with them in the end. Cutting back to save a little fuel may not be worth the extra soot that may build up due to the low fire when the thermostat kicks it back to the number 1 setting.

    Just hooked up the thermostat today and really like how it holds the temp right where I set it. Really nice feature!
  8. stoveguy2esw

    stoveguy2esw Minister of Fire

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    depends on timing, think of it this way , you get say...5 pellets in a dump of the auger (just to use a number) the exhaust blower is running on the default setting pulling (say for ease of math 100 cfm (it aint but...)) ok this setting will burn the 5 pellets completely in say 1 minute.

    ok , if you lower the LFF by 1 setting , then you get 4 pellets and at the air setting they burn in 45 seconds,

    the doses of pellets are say 45 seconds apart, this puts you close to the smoulder point.

    now here is where the low burn air can help or hurt. lowering the low burn air can increase that 45 second burn time to say 50 seconds, this allows the fuel itself to burn slower which may get you away from the smoulder zone. now, backing them both way down seems the logical adjustment , but its not so simple, as if you slow the air down too much , the pellets will burn evenly but not as clean or completely as we want. so , make small adjustments , and monitor your ash buildup as it will tell you if you are burning "rich' or not its literally like adjusting a carburator, so thinking like thats what you are doing helps. a rich burn makes soot , a lean burn is clean but less heat output , unless you go too far and get to smouldering , thats too lean which soots also. finding the sweet spot is the key. and with the variences in installs , fuel , and climate. no two are exactly the same.

    hope this helps, and the invite to talk is always open
  9. bret4

    bret4 New Member

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    That's just what I was thinking. That it must be like a rich or lean burn in a gas engine when adjusting the carb. Only difference is the fuel is solid and not a liquid. With that in mind soot is a big indicator of fuel burn rate. But to lean and no fire and the fire goes out. Engine stalls if were gas.

    Got you on it being a fine ballance of air and feed of fuel.
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