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barometric damper for gassifier - recommendations please

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by SteveJ, Dec 3, 2007.

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  1. SteveJ

    SteveJ Member

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    Okay, I sealed all of my air leaks per Anthony D in this thread

    The temps have cooled down and now my draft is too high (too much of a good thing!) - Seton W-130 at 9000ft with a 23' DuraTech chimney. My exhaust temps are 600-950F so it appears that a damper is in order.

    Questions:

    1. How many gassifier owners are using dampers?

    2. Those that are using dampers - manual (in pipe) or automatic damper tees?

    3. What is the difference between the Field Controls #B34TJ08B Auto Draft Regulator for $40.82 and the Field Controls RC for $122.85?

    4. What exhaust temperatures are gassifier owners running?

    Thanks,
    Steve

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  2. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Have you used a draft gauge (manometer)? If so, what's the draft?

    The first is a very basic unit, and very flimsy. They (or a very close equivalent from another company) come standard with a number of oil boilers. We typically throw them out and buy one like the second, because it is much more durable and easier to get adjusted. I think that price is a bit high, though, unless they are charging a premium for the black paint.

    Joe Brown
    Brownian Heating Technology
    www.brownianheating.com
  3. henfruit

    henfruit Minister of Fire

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    hi steve , ihave a green wood.how do you like the dura vent stove pipe?
  4. SteveJ

    SteveJ Member

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    Joe,

    No, I do not have access to a manometer - so I do not have an actual measurement.

    I was going based on my W-130 owner's manual which instructs that without a manometer the method to measure draft is according to exhaust temp - which should be 350-450F at a steady burn. Mine was always in that range until the temps dropped and the humidity went up.

    Do you recommend a different place to by the Field Controls RC model?


    henfruit,

    The DuraTech works great - very pricey but great. The DurVent stove pipe works fine - I just have a short horizontal 18" slip joint going to the DuraTech chimney.

    Steve
  5. antknee2

    antknee2 New Member

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    That's allot heat being lost out your stack . I recommended a high quality draft gauge made by Bacharach , I keep it in-line with the base of the flue pipe at all times . My Seton luckily stays between .05-.07 inches water. Are you using splits or big unsplit wood ? I think Fred recommends some sort of restrictor in-line with your chimney . Best bet would be to call Fred he knows all the secrets of your boiler. Anthony

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  6. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    You should get one. They aren't cheap, but they aren't overly expensive.

    I buy them from my wholesale suppliers.

    As Anthony mentions, restricting the flue is better than a damper, if you have excess draft. However, you need a draft gauge to do it right (even to set up a damper).

    You can do it "quick and dirty" by putting a partial block-off plate in there, and making it block more and more until you have the draft down where you want it (start with a tiny bit of restriction, and keep increasing it). Or you can buy and install a "butterfly" damper - just like on a wood stove - disk inside the pipe with a handle outside to adjust it from parallel to the flow, all the way through to blocking the flow.

    But you need a manometer, at least, or a draft gauge to adjust things safely.

    Joe
  7. henfruit

    henfruit Minister of Fire

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    anthony what are you burning for wood size? did you ever burn split and full logs? how are you loading it east to west or north to south.
  8. antknee2

    antknee2 New Member

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    [quote author="henfruit" date="1196746164"]anthony what are you burning for wood size? did you ever burn split and full logs? how are you loading it east to west or north to south.[/quote

    What seems to work for such a over sized boiler is five or six, oak splits on the bottom and the rest of the burning cycle use large rounds mostly old Oak and some prized Ash.I make sure the logs are right to left if you are looking into the loading door . Tell us about your system ? Anthony

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  9. SteveJ

    SteveJ Member

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    What manometers do people have? recommend?
  10. henfruit

    henfruit Minister of Fire

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    anthony if go to the boiler room,look at the thread by joe brown.listed as instalation it wiil explain and has pictuers of of his work. where do you have yours located? thanks pat
  11. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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  12. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    The Bacharach Draftrite poket gauge is pretty nice. Model 13-3000, if you want standard (inches of water) measurements.
    http://www.bacharach-inc.com/draft_gauges.htm

    Joe
  13. hkobus

    hkobus Member

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    Thanks for all the information here. I finally got around to find and install a draft control, the local fuel oil dealer had them instock, $Can 38.90.
    Probably some of the best money I spend this week.
    I used the EM200 (digital differential pressure guage) made by UEi, I use this unit to set barn ventilation.
    When I installed it yesterday we were in a massive snow storm and getting readings in the -0.21 to -0.14 In-W range. When done and set I got it to run in a -0.05 to -0.09 In-W range.
    The result, using way less wood. The excessive draft was keeping the unit almost going full and sucking the heat through the chimney. Now the flame is more steady and the "puffing" is history.
    I was able to have a load of wood last all night, from 10 pm to 6 am. I have not been able to do less than 5 or 6 hr intervals.
    This weekend I will tap a measuring port in the boiler connector pipe so I can do more frequent readings to adjust when needed.

    Henk.
  14. SteveJ

    SteveJ Member

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    Thanks for all the information.

    I have a manometer and a butterfly stove pipe plate.

    During December, I was getting drafts up to 0.12" wc and used the butterfly damper at about 45 degrees to reduce the draft to about 0.07"wc.

    Now the draft is down and I have to go to 0.05" wc or less to keep the exhaust below 700 degrees.

    I talked to Fred and he said to watch the fire creep and to seal the air intake with car exhaust gasket material.

    I have done this but am still getting exhaust temps up to 800 degrees with the draft below 0.05" wc.

    Is anyone else running a Seton at or above 9000 feet?

    Any suggestions would be greatly appreciated.

    AnthonyD - where exactly are you taking your draft measurements? Do you ever see exhaust exiting beside the air intake tubes (I have observed this when the boiler is pulsing)?

    Steve
  15. antknee2

    antknee2 New Member

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    Hi Steve I have a low cost idea for your situation , try blocking off the outer air intake tubes with some high temp insulation , let me know the results . Also what size , type ,and moisture content wood are you burning ??PS I do not have any experience with the way things operate a your altitude I live at 600' . One other thing I found with this boiler the cooler you can keep the 29 tube heat exchanger the cooler your stack temp is . I added a separate circulator with 1'' pipes feeding a heat exchanger in my # 2 Super Stor storage tank . Anthony

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  16. SteveJ

    SteveJ Member

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    Anthony,

    Great idea - the outer tubes have creosote drips at the back when I was using the rope/tape gasket. Pictures below.

    The manometer (disconnected in the pic) tube, before the stove pipe damper and before the exhaust temp gauge is in the second picture below.

    I have replaced with the gasket on the flap per Fred.

    Also, when there is puffing - loading a lot of small wood and starting with stove pipe damper fully open, the exhaust can be seen coming around the air intake tubes and being sucked back in...

    I am burning beetle kill pine and fur - unsplit and dead for more than 3 years - recently cut with diameters from 1" up to 16" with average around 6".

    I do not know the moisture content.

    I recently took the stove pipe exhaust off and cleaned out about 2 gallons of ash from the exhaust floor.

    Thanks for the great advice and the great pics.

    Steve

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  17. antknee2

    antknee2 New Member

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    Steve I think the super dry pine is the simple cause of your high stack temp . I read that pine has the most energy per pound , the sap is super high octane . probably the combo of your altitude , the insane primary air and your wood are the perfect Storm . Also make sure the primary air intake tubes are pushed in all the way an sealed with ht silicon. Anthony
  18. SteveJ

    SteveJ Member

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    Anthony - will do... Thanks again for your great advice.

    One more question:

    The Seton manual recommends exhaust temp and draft - exhaust in the 350-450F range and draft in the 0.05-0.08" wc range. Which is the overriding measure?

    I asked Fred and he basically said to reduce the draft until the boiler drips and then increase until the dripping stops.

    The dripping is in the back corners as shown in the pictures below.

    Thanks again,
    Steve

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  19. antknee2

    antknee2 New Member

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    Steve my boiler drips in the same spot even with the three heat heat exchangers and three 120 gallon storage tanks . I keep a old towel below the drip . By adding a second circulator tapping off the 1 1/4'' feed and return , and dumping it into super stor # 2 hx the boiler seems ultra efficient . Also I found a way to clean the back side [hidden ] pressure vessel tubes . Next time I clean it I will post some pics. Thanks Anthony
  20. SteveJ

    SteveJ Member

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    Anthony,

    Cool - cannot wait to see the "hidden" cleaning...

    Steve
  21. jebatty

    jebatty Minister of Fire

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    I have been watching this thread since the beginning and something about all of this just doesn't make common sense to me. So, I need to be educated. Let me know where this is in error.

    To me, draft and stack temp are directly related. Unless there is an air leak or air is being added by a barom damper or the like, 100% of the draft is pulling air through the burn and out the stack. The more air pulled through the burn, the more burn and heat is generated. Heat in the stack is easily measured with a probe thermometer. If stack temp is where it is "supposed" to be, then draft has to be "correct." And vice versa. Too hot, too much draft; too cool, not enough draft. Assuming of course, good wood, good boiler design, good path for the burn gases to escape, etc. The same thing can be achieved by measuring draft directly -- the higher the w.c., the more air, the more heat, and vice versa.

    Now, if somewhere there is dripping coming down through the stack or somewhere in the exhaust stream, and stack temp is where it is "supposed" to be, something is wrong. If the condensation is water, that condensation is not likely to be occurring in that part of the stack where the temp is 350 or more. It's too hot. Water will vaporize to steam. Water condensation has to be occurring where the temp is a fair amount less, probably higher up the stack where sufficient temp is not being maintained to prevent condensation. If it's water condensation, I would look at the chimney design and find out why the upper stack is cool enough to condense out the water, and so much water that it can drip back down through the hot part of the chimney. Can the wood be way too wet? Are there air leaks somewhere? Is the chimney so long and in a cool environment that the "supposed" to stack temp can't heat the chimney all the way up? Assuming proper boiler design, there has to be a chimney problem.

    If the condensation is not water but tar, goo, creostoe, yuck, etc., then combustion is not complete enough and unburned wood gases are condensing out. These can condense also, but I understand the temp needs to be less than about 250-300 or so for this to happen. A well-designed boiler up to heat simply should not have unburned gases in the exhaust steam of any consequence. Non-water consensation should not occur except possibly on fire up until the boiler is up to heat and possibly on cool down, although should not happen here because there should be nothing left to burn -- that's why the boiler is cooling down. So the problem source has to be a problem in boiler design or operation which is allowing unburned gases of consequence or again, a chimney problem.

    or . . . is there extra wood be thrown in near the end of the burn of too little quantity to get the boiler back up to heat, so there are unburned gases?
    or . . . is the bypass damper not closing all the way or leaking and allowing unburned gases and water vapor from the firebox directly up the stack?
    or . . . (other ideas?)

    Last, stack temp where it is "supposed" to be may be the "source" of the problem, assuming proper boiler design and operation, but this also has to relate to a chimney which is not the "ideal" chimney. The stack temp may have to be higher than the "supposed to be temp" due to the particular chimney design and location factors. If the chimney is too long, or too cool, or too many bends, or . . ., more heat simply might be needed to heat the chimney all the way to the top and achieve proper operation, albeit at some reduction in maximum possible efficiency given ideal conditions. Stack probe temp about 18" above the flue exit from the boiler can be 600 or higher, perhaps even 800, without causing a problem for a stainless steel, insulated chimney properly installed and in good condition. Obviously, we want to burn at the minimum temp needed for good boiler/chimney operation and thereby at as high an efficiency as we can, given our particular circumstances.

    The threads (or mfr recommendation) suggesting stack temp of 300-400 are not wrong; in my mind they simply relate to "ideal" chimney conditions and "ideal" wood and "ideal" boiler operation which translate to maximum efficiency. Those temps are where we all would like to be, if we could, buy we all can't.

    For those who can achieve this, they are lucky. I have a feeling, unless most of us have ideal chimneys and ideal wood and operate our boilers perfectly, most of us cannot consistently achieve that given our chimney design and our wood type and moisture content and how we actually operate our boilers, all introducing many variables. For me, with my 22 foot chimney through a cold attic, and burning very dry pine slab wood, my probe temp will be 450-500 during most of the burn, with a peak of just under 600, and end of burn down to 300-400. My boiler purs on this, produces the heat I need, and no smoke, no creosote, no condensation, practically no ash, and no problems. For me that means this is the correct temp, regardless of any "supposed" to temp.

    As mentioned above, please correct me where I am off base. Education never ceases.
  22. antknee2

    antknee2 New Member

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    Jim I think you have have a awesome understanding wood boiler operation . What type of system do you run , could you post some pics. Anthony
  23. Eric Johnson

    Eric Johnson Mod Emeritus

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    If it's creosote, there should be some uncondensed smoke coming out the chimney, it seems to me.
  24. jebatty

    jebatty Minister of Fire

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    I think you have to be right, Orlan EKO 60, if I understand you correctly. If there is true smoke, and not just water vapor, there are unburned gases, particles, etc. making it out the stack which are condensing/precipitating in the cooler ambient air. Depending upon stack temps, they also could be condensing in/sticking to the stack. If the stack is hot enough, they just will escape to the air and condense there. But keep in mind, on initial burn the stack is cold and burn is incomplete, and there likely will be some condensing of creosote in the stack. However, as the boiler reaches operating temps, stack temp increases and ideally should burn off the previously condensed creosote. In many cases this will not happen perfectly, which is why we clean our chimneys.
  25. jebatty

    jebatty Minister of Fire

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    Addendum - there always will be water vapor, as water is a by-product of combustion. The burning of 100% dry wood still will produce water vapor through the chemical reaction of burning -- oxygen is combining with hydrogen to form water, one of many chemical reactions occurring, and, if I remember my chemistry days correctly, the process of these chemical reactions releases heat.
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