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What exactly is idling?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by infinitymike, Oct 23, 2012.

  1. infinitymike

    infinitymike Minister of Fire

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    Now before I get bashed to death here, I am asking a very serious question.

    I know there has been a lot of banter about the wood gun not idling and other units that do idle.
    So for clarification I would like YOUR definition of idling.

    MY definition of idling, from what I have read here, is when the boiler has reached its high water temp set point and the unit goes into idle mode by lower the fan speed down to a minimum or the fan shuts down but air is still being pulled into the fire box through the primaries from a natural draft. The gasification process stops but all the while there are still flames and or smoldering coals and splits in the fire box.

    Does any body have a video of their unit in idle mode?

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  2. BoilerMan

    BoilerMan Minister of Fire

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    I do have to admit, when I saw the title.....then read infinitymike.....I had quite a smirk on my face. Idle is a state in which the boiler "stops the fire" to avoid overheating. It does still smolder to a degree from natural draft, which varies due to factors like chimney height, boiler type (forced draft vs. induced draft). If a fire is able to "relight" itself and the process of gasification can continue a boiler/fire has been in idle state (little fire gremlins or not). As what I've seen on your vids the air damper closes off the air to the fire which is the magic "no idle" WG trick. This is what makes the WG "stop" but there are still coals that would suffocate if there were not some small miniscule air to them. Put a jar over a candle and see if it re-lights after it goes out. When your WG "idles" it shouldn't tar up like others because of the air damper stopping the draft forom the chimney. Other boilers with a high degree of natural draft pulling the smoke through the firetubes can tar up, but generally don't due to high temps of the tubes themselves, plus it should burn/evaporate off when the secondary combustion resumes. A boiler that shuts off completly would have to have an electric or propane igniter to relight the fuel....... like a pellet boiler.
    And no, I didn't copy and paste any of this post.
    My $.02.

    TS
  3. infinitymike

    infinitymike Minister of Fire

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    I'm sure I put a smirk on a lot of peoples faces, but I am not trying to be a wisenheimer.
    I explained what MY understanding of what YOUR boiler does, and thats all it it is, MY understanding.

    I'm looking for an actually step by step process of how other boilers idle.
    I know how mine idles and want to see if mine does the same as others do.
    Maybe we have all been bantering back and forth and we are all doing the same thing just with a different definition.
  4. Gasifier

    Gasifier Minister of Fire

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    Definition of IDLE

    1: lacking worth or basis : vain <idle chatter> ;lol
  5. willyswagon

    willyswagon Burning Hunk

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    When I look at gasification boilers I use the comparision to a Dragster at the track.
    It is either Full throttle,when the fans are on supplying air to the fuel, or idle when the fans are off, or flaps are closed to reduce or stall out that reaction.
    All the time sitting there idleing with minimal combustion waiting for the light to turn green then full throttle again
    Final round 2007 Gator Nationals, Wendal Howes for the win

    [​IMG]
    Gasifier likes this.
  6. maple1

    maple1 Minister of Fire

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    Mine doesn't idle. It burns flat out until the wood is all gone. The air inlet door is always open. Just the way it was designed. Hence the requirement for storage - and also the inherent simplicity and no requirement for a fan. I think Taylor has idling pretty well nailed in his words - I'd say simply it's damping or suffocating the fire before it burns itself out.
  7. henfruit

    henfruit Minister of Fire

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    Just think of it as a camp fire that you had burning for a day and night.You get up in the am to just ashes, no or may be a wisp of smoke.Stir it up a bit add some birch bark and wood and breakfast will be ready soon.
  8. kopeck

    kopeck Minister of Fire

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    My boiler will idle a bit when it gets to the end of it's burn. Usually the water in the tank is around 170/175. I need to play with the circulator speed a bit and see if I can move the heat a bit better.

    I think that's probably the biggest downside of my unpressurized storage with a coil vs the pressurized tanks. I don't think my setup transfers the heat quite as efficiently, especially when the tank water is getting close to the hot water coming off the manifold.

    It doesn't idle long, probably around a minute or so then it fires up and keeps trucking. Sizing the load of wood also helps a bunch, to much wood and no where to put the heat is going to cause idling no matter what your setup.

    I talked to the guys at Tarm about it idling a little bit and they said that was perfectly fine, pretty much it was doing what it was suppose to be doing. Long idles would be another thing entirely.

    K
  9. hiker88

    hiker88 Burning Hunk

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    SLUMBER- Fan off, primary 20%, secondary is closed, circulator pump runs. The Froling will go back to gassifying if the boiler temp returns to the setpoint and the stack temp is not below 80c (the boiler considers the burn done at 80c and goes to OFF(fan off, primary and secondary totally closed, circ pump runs down to 65c). I know this because I'm still learning.

    SHUTDOWN - boiler hits 93c - primary and secondary totally closed, fan off, circulator runs - will not restart without physical reset of "STL" switch.

    Of course the beauty of this unit is watching it between temps of 87-92c... It is truly a thing of beauty.
  10. kopeck

    kopeck Minister of Fire

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    h
    Since you have a similar setup to mine (same storage, same boiler output) do you see the same happening with your setup (ie it idle/slumbering as the tank nears 180 deg F)?

    The Frolings are really something else, one of my neighbors has one.

    K
  11. Gasifier

    Gasifier Minister of Fire

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    An h&K. I have a nice one of those. The "stack" temps get hot really fast in it. :)
  12. Fred61

    Fred61 Minister of Fire

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    Since I installed my storage tank four years ago, idling hasn't been a problem for me. I batch burn, meaning that when storage needs charging, I light a new fire. With experience, I am able to predict how much wood to load so when the storage approaches 180::F the firebox only contains a moderate amount of hot coals that have had most of the moisture baked out of them and produce very little or no creosote on the walls or other components. My circulator launch temperature is very high at
    178 degrees and my overheat circulator launches at 185 degrees so when the temperature is high I have two circulators pumping water to seperate coils in my tank which drastically reduced idling when temperatures of storage start approaching high limit. The overheat circuit circulates water through a coil in the bottom of the storage tank. When the boiler does go into idle, it isn't in that mode for long. Since I am normally around when burning, I just shut off the master switch when the tank has reached it's maximum set tempeature. Since I am controling the circulator with a Tekmar control, my circulators are off either with the high limit switch or when the combustion fan continues to operate before the low temperature shuts it down in the absence of fire the integrated differential temperature control keeps my system from loosing heat.
    I don't even recall what intervals my cycle timer is set at since it is almost never used. In the EKO I think that whimpy little flapper door just inside the fan port could be overcome by the flue draft although I usually shut the boiler down with coals left in it in order to have speedy gassification on the next fire and they are usually there when I fire it the next time.
  13. I don't see a big difference between a wg on most other down drafters. The woodgun uses a motorized damper to stop the air flow. Others uses a weighted flap.

    The woodgun stops more of the air flow, stopping the fire quicker. Which can have the downside of causing a failure to reignite if there is a prolonged period with no call for heat.

    Others use a little more wood when ideling. But don't have the problem of reigniting.

    Almost all installs benefit from storage -- which will increase boiler life, WG uses stainless to prevent there boilers from rotting due to there storage isn't necessary strategy.
  14. stee6043

    stee6043 Minister of Fire

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    I would agree with the idle comment. Our boilers may enter into and maintain idle in slightly unique ways but this does not change the physics of what's going on in the upper chamber when there is no fan on and our flaps/shutters are closed. I'd bet you could not measure the difference in output/efficiency of the WG idle vs any others. The marketing guys from one manufacturer may call it "relighting" but it's no different than blowing on the hot coals of your camp fire in the morning. As far as I know no boiler manufacturer has invented a new kind of fire....yet.
    mikefrommaine likes this.
  15. hiker88

    hiker88 Burning Hunk

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    Yes it will actually. It will do everything it can to maintain gassification and keep the temps near the set point - but there comes a point if there is too much wood in there, and the return temp from storage is high - somethings got to give as they say.

    One thing I had to get my head around is the fact that once your return temps start to push 165, the storage starts trying to cool the boiler. The documentation on my loading unit actually says something like "once the unit senses 185f water, the return is fully open to allow maximum cooling of the boiler". So it seems to me, if you are trying to cool something that doesn't want go much above 187 (my setpoint) with water that is 165-185f+ water that can only go on so long before you have to idle.

    The only way I can think to avoid idling and try to get those kind of high temps in storage is to get the right amount of wood in there, so that just as you are pushing the setpoint, the wood starts to burn down and go out. Yesterday, I had too much wood, so I got some idling, but I got my storage to about 195f.
  16. skfire

    skfire Feeling the Heat

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    I found that is the ticket..

    I'd rather judge on the low side, than the high side. Avoiding slumber, idling at all costs.
    Getting the hang of it, but weighing the wood is the best approach for exact assessments of load required to reach highest possible desired storage...not that in my case that is imperative..I am happy for one day's stored BTU supply in dead of winter with 185top/180bot. One fire does that from my needs.

    Avoiding any type of build up is key for me.

    Scott
  17. kopeck

    kopeck Minister of Fire

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    What liner do you have, the yellow one or the clear one?

    I've never got my tank over 185, which is fine since my PVC liner is only rated 180 F/ 200 F intermittently. I usually live between 175 F and 180 F.

    You are 100% right though, it's all about matching how much wood goes in the firebox to what your system load is. It's very easy, and tempting to throw extra in but in the end it's not getting you anywhere. On the flip side the one or two really cold days we had last year I found my self throwing a few extra sticks in before I went to bed (I usually light he second fire around 8:00 PM). It's sort of getting a feel for your system which takes some time.

    K
  18. hiker88

    hiker88 Burning Hunk

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    Here's a visual for everyone:
    Gasifier likes this.
  19. hiker88

    hiker88 Burning Hunk

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    I have the yellow one. It's actually two liners and a vapor barrier. It's rated at 200 continuous, but like you, I'm thinking that one load of wood gets me up to 175 -180 with no worries about idling so that is probably what I will usually shoot for.
  20. JP11

    JP11 Minister of Fire

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    Mine does not Idle, or your word STOP like yours.

    Your's shuts itself off.. and it may or may not re-light, depending on how long it has been since it was on, Correct?

    Now.. you can say off.. but I stick with my physics, and say that you MUST have a coal there that can be forced with air to re-ignite.

    But.. you asked about MY boiler.

    Mine.. in idle.. continues to run my pump. My guess is that it goes into "MAX" mode at 195F. It shuts the draft opening. It stops my two combustion fans. One of two things will happen at that point.

    1. boiler and storage temps drop (my guess is 180 or so..) and the draft opens back up, and the fans start back up (if it's out of wood, or if it does not relight.. the boiler will know that by lack of stack temp. I have my min stack temp as 200. it will then shut down completely)

    2. one hour in "max" mode has elapsed. the boiler will momentarily open the draft, and spin the fans back up to KEEP the coals alive.

    But.. what do I know.. I filled my boiler full this morning. and it's sitting in max mode maintaing temps at 196 top to bottom. It will do so until it runs out of wood. I'm away for 8 days.. so the wife's gonna have to get to work tomorrow night probably.

    JP
  21. flyingcow

    flyingcow Minister of Fire

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    I've found with my tank(solartechnics) once i get to 170's the boiler is starting to idle more. It takes a bit of wood to push it above 180. For me, it's not worth it. But you Froling' guys are kinda spoiled.:p

    I know my tank isn't as fancy as a pressurized tank, but the HX's in this one really can dump(and pull back out) some BTU's.

    To me idling is idling. Different variations maybe.
  22. That is pretty much how my boiler works (rk2001 controller) Except it doesn't use a flue gas sensor to determine if it is out of wood. If after a period of time it does see a rise in the water temp it will shut off the fans and continue to run the pump until it reaches 145. All the setpoints are user adjustable so you can set the max temp, when the pump turns on and off etc.

    Most gassers seem pretty much the same, slightly different terminology and various colors of sheetmetal. But at their core pretty similar.
  23. henfruit

    henfruit Minister of Fire

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    I think we should call it smoldering .We are combusting wood.
  24. kopeck

    kopeck Minister of Fire

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    Yeah, I should say mine tops out more often at 175 then 180. You are right, getting that extra few degrees seems to require a lot of extra wood. Pretty much 180 isn't worth it, to much wood and to much idling IMHO.

    I've got the 820 gallon bank and Solo Innova as well.

    K
  25. infinitymike

    infinitymike Minister of Fire

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    Now thats what I'm talking about,all of us playing nice in the sandbox.

    We all pretty much said the same thing.

    Let me explain how the wood gun operates.

    1. Put wood in and light fire. Fan is on and air valve is open
    2. When water temp reaches high set point, which for me is 190*, the fan shuts off and air valve closes. Now I guess this could be considered slumbering, idling or off.
    The unit can sit in the mode for several hours.
    3. When water temp drops to low set point which can happen by being shut off for so long or because water is circulating water for a heat load, my low set point is 170*, the fan turns back on and the air valve opens.
    Now 2 things can happen here, 1. either the fire starts up again or 2. nothing. if 1. happens then the water temp will rise and the unit will shut down when it reaches high set point. If 2. happens the water will continue to cool until the second low temp set point is reached which is 150* and the unit will COMPLETELY SHUT OFF and the relay will then activate the oil burner !!!

    That kinda of sounds like some of the boilers here but some sound like there is still a fan or a natural draft which is keeping the fire barely alive.

    Hopefully we can continue to all get along and enjoy our fires when they are burning full throttle and heating our homes.:cool:

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