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Baseline fuel/burn specs/feed rates for Englander 25-PDVC

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by wundercat, Jan 6, 2008.

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  1. wundercat

    wundercat New Member

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    Right now, I'm looking for the theoretical ideal hopper-emptying times for settings 1-9 for my 25-PDVC. (40lb hopper)

    I realize that the feed rates need finer adjustment to get the burn correct for any given pellet brand. But, knowing my ideal
    target times will be a good place to start.

    Suggestions for Englander:

    1. There should be a comprehensive feed rate chart in the manual with columns based on average pellet size, since there are now so many different pellet brands to choose from, all with minor differences. This would give everyone a baseline setting for getting started.

    2. There should be an overall feed-rate adjustment procedure in the manual.

    3. Lastly, there should be an additional second layer rotating fine-adjustment restrictor plate with a max of 80% restriction
    for use with some of the finer pellet fuels so that they don't overfeed and form a lava-clinker. The plate only needs to be rivited to the free end of the lower course restrictor plate that's bolted down.
    Then you could just put a solid rod straight up through the pellets, in the middle of the hopper, with a handle that sits just low enough to that the
    hopper door doesn't hit it. Then restrictor plate fine adjustments could be made "on the fly", no wrenches and no emptying of the
    hopper needed to make the adjustment.


    I have to say that I'm pretty pleased with the overall quality of this stove. It actually kept about 1600sq ft of house at comfortable temps through that last cold spell.

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  2. pegdot

    pegdot New Member

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    I believe, but I could be wrong, that the numerical feed rate settings correspond roughly to the number of lbs. fed per hour. In other words, setting 1 equals 1 lb. per hour, setting 9 equals 9 lbs. per hour.
  3. wundercat

    wundercat New Member

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    Thanks pegdot.

    Any further input from the Englander folks to verify this?

    Thanks.
  4. bret4

    bret4 New Member

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    I have been looking at getting a 25-PDVC lately and talked to someone at Englander about the pellet feed rate. I was told that 1lb of pellets to makes 8000 btu of heat. On the low setting it makes 12000 btu's and uses 1.5lbs of pellets per hour. On high it makes about 40000 btu's using about 5lbs of pellets per hour. That is what I was told on the phone today.
  5. webbie

    webbie Seasoned Moderator Staff Member

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    "makes 8000 btu" means INPUT. That is not the output of the stove. A lot of that heat goes up the chimney. So keep that in mind. It is better to use a figure like 6000 BTU output per pound if you want to know how much heat is actually being released into the room.
  6. stoveguy2esw

    stoveguy2esw Minister of Fire

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    on the average premium grade pellets supply approx 8500 btu on the input side, EPA minimum for default is 78% efficient. so to see what you are pushing out the front multiply the average btu potential of the pellets by .78 this should give you a rough idea how much heat you will produce on the output side for example 8500 X .78 = 6330 so 5 lbs per hour at this rate will release 33,150 btu on the output side

    a unit with an "actual" epa efficiency rating could be as high as 83% ( at least thats what i think i saw one rated at once) so you would use the same math but multiply by .83 instead.

    its also important to note that by accepting default , the unit will be rated at 78% but that doesnt mean that is how it did , it has to meet at least that, but can be higher, but the manufacturer doesnt want to deal with the added expense (which is considerable) along with more frequent recertification (also quite expensive) involved in maintaining that rating.

    craigs numbers up there are actually good baseline numbers to shop with though as the math is much easier to work out in your head and will not be off much
  7. stoveguy2esw

    stoveguy2esw Minister of Fire

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    actual testing to determine the rates involved would be a nightmare and since you can have size differences literally from bag to bag it would really complicate things usually an experienced user will "figure out" within a bags time where to adjust to get the output desired[/quote]
    [quote author="wundercat" date="1199650679
    2. There should be an overall feed-rate adjustment procedure in the manual. [/quote]

    feed adjustment is simple , the "heat range" setting on the unit allows for 9 heat ranges which increase fuel flow as the number is increased, and lowers feed rates as it is decreased
    [/quote]
    [quote author="wundercat" date="1199650679
    3. Lastly, there should be an additional second layer rotating fine-adjustment restrictor plate with a max of 80% restriction
    for use with some of the finer pellet fuels so that they don't overfeed and form a lava-clinker. The plate only needs to be rivited to the free end of the lower course restrictor plate that's bolted down.
    Then you could just put a solid rod straight up through the pellets, in the middle of the hopper, with a handle that sits just low enough to that the
    hopper door doesn't hit it. Then restrictor plate fine adjustments could be made "on the fly", no wrenches and no emptying of the
    hopper needed to make the adjustment.[/quote]

    interesting concept, but would be an item which would have to be rather tough in structure to handle having pellets poured in on top of and around for years on end, also an 80 % restriction of the opening would likely lead to some serious bridging issues. may end up being a headache for some users. the restrictor plate does help with smaller length pellets but usually its not somthing that is frequently adjusted as most users tend to settle in on one or two brands of pellets for the most part and at least in my case i adjust for smaller pellets with the restrictor plate rarely in my unit.
    [/quote]
    [quote author="wundercat" date="1199650679
    I have to say that I'm pretty pleased with the overall quality of this stove. It actually kept about 1600sq ft of house at comfortable temps through that last cold spell.[/quote]
  8. bret4

    bret4 New Member

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    Really interesting! Makes a lot of sense that you lose some btu's up the chimney and in the effciency of the stove.

    Now all I got to do is decide if I should get the 55-SHP10 for $900 at lowes or wait and see what Home depot is going to sell the 25-PDVC for when they have their end of season sale. :) Should be a lot better than loading wood in my small wood stove every 2 or 3 hours!
  9. webbie

    webbie Seasoned Moderator Staff Member

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    Mike, you are not adjusting the wood for the moisture content. 20% firewood ends up at about 7000 BTU input and pellets with 5-7% moisture end up at about 8000. Even PFI and the US Forestry Service claim a Gross Heating content (input) of approx 8,000.....so I'm using that one.

    I think 75% will eventually be shown to be generous in terms of "actual" (over the entire burn, including startup, shutdown, hi, lo) - efficiency, and my thinking is that it could be much lower as heat exchangers get dirty, etc. - I am using gas as a comparison - gas stoves that burn over 80% efficiency (steady state) have been tested for actual (total) efficiency by the Canadian Government in the low 60's! - Even some with electronic ignition (no pilots!). I can't imagine how a relatively dirty and less controlled (combustion wise) biomass heater could come in higher!

    I always try to promise on the conservative side or accurately, because in sales the tendency is usually the other way...someone has to counteract all the hype (and why not me?).
    :coolsmile:

    (too many years spent in the shop hearing about how people smoldered two logs for 14 hours and heated their whole house!)

    Corie can probably inform us of EPA Pellet stove efficiency testing....if, as I suspect, it is "steady state" (taken during the test run), then I'm certain that he and other combustion experts know if will be adjusted far downward for an AFUE or Energguide type, which takes all that other junk into consideration.

    Bottom line, as Mike and I seem to agree on, is figure (and hope for) 6,000 BTU per pound pushing out of your stove - worse probably with an insert....but not by much in a pellet insert (as opposed to wood).
  10. bret4

    bret4 New Member

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    Sorry that this is not all pellet related, but.

    Today I was talking to a guy at work. He told me that he burns about 18 pieces of wood about 20 inches long and about 3" to 4" dia. in 24 hours in his wood stove. My stove is a small stove that can only fit 2 to 3 pieces of wood about 16" to 18" long. Really rough math in my head tells me that we must use about the same amount of wood to burn the same 24 hours in our stoves, even though his is a much larger stove.

    My little stove gives me only about 2 hours burn time on say 2 pieces of wood. His can hold at least 8 pieces of wood and get about 8 hour burn time. It seems to relate close enough to 1 piece of wood per hour for both of us.

    Now with the pellet stove I would hope the btu's would be more steady than the wood stove per burn. Even say at full power with the 25-PDVC / 55-SHP10 stove at around 5lb's per hour you would burn about 40lbs in 8 hours. That to me would seem to be close to the same amount of wood as the wood stove. Only things that may not make that true is that in a bag of pellets there may be more air space between the pellets than I may have accounted for. Also the wood would have a lot less control over how dry it is, being stored outside.

    The point being that maybe it would be possible to get even more out of the pellets per weight due to better control of what you are burning. Long steady burns on the pellet stove even at lower heat setting should be better than my hot to cool, up down cycles on my wood stove. I'm thinking that a 40lb bag should give a longer burn time at a lower heat setting than the wood stove and be just as comfortable.

    Does any of this make sense? Or am I off track on this?

    Hey, if nothing else wood is more of a pain than pellets due to the work factor.
  11. webbie

    webbie Seasoned Moderator Staff Member

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    Bret, you are definitely onto something, which is true with both pellets and gas, etc.

    The fact that you can, to some degree, turn the units off and on, and up and down.....that definitely saves some fuel....sometimes a lot.
  12. stoveguy2esw

    stoveguy2esw Minister of Fire

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    i'll tell you (and this is my own persoal opinion) steady heat , even if at a lower btu output is more comfortable than a "high/low" heat source. pellet stoves heat differently in my opinion than woodstoves as they give more control to the user, granted an experienced woodburner can "dial in his stove" but the wood itself is consumed at a varying rate during a fire and does not afford quite the control afforded to a pellet burner. for instance , take a cold room , add a woodstove , load it up and let it rip, certainly the woodstove is going to bring up the room temp faster as its simply more effective at that chore. however , if not attended to within 4-8 hours the woodstove is done and temps will fall if it isnt reloaded and fired again.this is the biggest reason why folks look so hard at burn times, so they can expect an all night burn so they do not have to get up and reload. on the other side of the fence, a pellet stove will not bring a room up like that in most instances as rapidly , but once there , it will sustain for a longer period without attention. now here's where my idea on it starts; heating air is rapid, but air also loses heat rapidly as the heat is absorbed into solid objects walls, ceiling, furnature etc... a constant heat will warm the solids up as well so over time the whole structure warms up. depending on start time a pellet unit will still be providing heat long after a woodstove needs to be refilled. both will do the job , but one is more convienient. both have advantages. both have disadvantages. the biggest key is decidinig on which to use, and properly sizing the unit for the job at hand and the lifestyle you wish to lead using it.
  13. bret4

    bret4 New Member

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    That's just what I was thinking. Once the place is warmed up it is much easier to hold the same temp. In my basement when the cement walls and floor get warmed up they help stabilize the temperature.
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