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OWB with storage question

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by taxidermist, Jan 10, 2013.

  1. taxidermist

    taxidermist Minister of Fire

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    I am helping a friend with a OWB ,do you think adding storage and running the boiler like we run our gassers would make a big difference on how much wood he burns?


    He only burns 2 year seasoned ash and oak but with a 2200 sqft log home he burns 24fc from OCT till april.

    He has pretty good insulated underground lines and only loses about 1 deg in 50'

    Thank you for any help,
    Rob

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  2. heaterman

    heaterman Minister of Fire

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    Tough to say Rob. Part of his issue is the fact that he has an OWB and there is virtually nothing you can do to increase efficiency on that type. They are so poor on actual heat transfer that cycling the fire becomes secondary.
    The other part of his high consumption could be air infiltration in his log home. I've done several and all of them have taken more to heat than one would think. Really tough to get one sealed up and keep it that way.
  3. taxidermist

    taxidermist Minister of Fire

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    Interesting! I would have thought the a log home would be tight... Good thing i never built the one i wanted. LOL

    Why is the heat transfer so much different than say a garn or a eko ect?

    Rob
  4. Fred61

    Fred61 Minister of Fire

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    Not unusual wood consumption for the combination of OWB and log home. They talk about the insulation qualities of wood but are giving it more credit than it deserves. But the big problem with log homes is infiltration which tops the list for heat loss. Some log home fastening systems are better than others. Those that allow the logs to slip when the wood shrinks are the best. If they don't allow the logs to settle, you can end up with huge cracks between the logs. Another problem that arises is when you put in interior partitions and don't allow for shrinkage when attaching them to the outside walls. It must be a slip joint. Huge gaps can appear. Most, underestimate the amount that a log will shrink when drying. That's why some wood piles fall over.
    I doubt that storage will be of any benefit in this situation.
  5. JP11

    JP11 Minister of Fire

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    I know those guys claim the OWBs are so insulated....

    but really.. It's what.. 500 to 1000 degrees inside.. and freezing outside the boiler. How thick are those fiberglass walls around the OWB?

    It's science man. He's trying to heat the earth a bunch too.. not just his log cabin. :)

    JP
  6. taxidermist

    taxidermist Minister of Fire

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    I already pointed out the lack of insulation on the owb. This will be addressed with spray foam this summer. I already gave him the OWB speach so dont lay me out for his OWB he already has it so we are just trying to improve it some..... I know I cant make it a gasser but I know i can improve it some.

    Rob
  7. JP11

    JP11 Minister of Fire

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    LOL.. I wasn't lumping you into the crowd.

    Just love how those salesman can ignore PHYSICS!

    :)
  8. maple1

    maple1 Minister of Fire

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    I think he might gain some efficiency with storage - but it might not be worth the expense & trouble of doing it.

    The main thing that would make me think twice is - don't these units depend on constant fire and flow of water to keep from freezing? (I didn't think they used glycol but maybe they do - correct if wrong). So if you stored enough water to run the boiler intermittently, you might have a risk of freezing something?

    24 fc = 8 real cord. That actually sounds pretty decent for an OWB - I also think I might try just adding more insulation to it or some shelter around it. Also sounds like he's seasoning too so he's prety far up the curve already with likely not a lot more to be gained.
  9. JP11

    JP11 Minister of Fire

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    For less money than storage.. He could build a little shed around it. It would let him have a nice, dry storage area. Would also cut down on losses out the sides of the unit.

    He also wouldn't have the stigma of having someone see one of those foolish things out in the yard!!

    :)

    Sorry.. had to get that dig in.

    he's still way better off than paying the oil man.

    JP
  10. mwk1000

    mwk1000 Member

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    Funny, this is the exact same amount I have used for years.
    At first it went into my fireplace insert and "helped" offset my heating by about 1/4. Now it goes into my gasser and heats the home completly.

    About the wood insulation, funny that all the conventional home insulation guides make a point of attemting to creat a barrier between the studs and the outside to stop conducting the heat. A log home would then be what ????

    Sorry , one of the guys I work with has one as may people do -- they are beautiful but functionally poor in many ways.

    My gut says he needs a heat loss , even a quicky from "build it solar" to see how much is the home and how much is the boiler. If it's all low exchange and the house is "ok" then I would seriosly look at dumping the OWB since he may be doing 4 years of work each year. What is that worth ? I heat a very large home with the same wood. Hard to let go of the money spent I know but my head says :

    Street price for 24 Face cords in our area say 1500.00 @ 65 prices I see are from 55-75 so every year he is wasting 1000.00 or more in labor. Or he could cut 24 face and then play for 2-3 years ... :) I'd be looking hard for a used gasser to get out of that trap.
  11. maple1

    maple1 Minister of Fire

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    I don't think he could reduce his wood consumption from 8 cords a year to 2 no matter what he would replace his OWB with.

    But your post is kind of contradictory in that you say you burn the same amount?

    I'd just insulate/shelter it, and run it until it gives out.
  12. taxidermist

    taxidermist Minister of Fire

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    Thanks for all the reply's, they own a good size woodlot so wood only cost time and fuel to cut. I do like the idea of putting them in their own building with wood stacked in it too. I always tell people with them that your raming frozen wood into a fire box then blowing ice cold air into the fire box and you want it to run hot???? HMM LOL


    Rob,
  13. mwk1000

    mwk1000 Member

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    I guess I left out the fact that I am heating close to 8000 sq ft, that was the point. Almost 4 x the area
  14. bigburner

    bigburner Feeling the Heat

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    We did a log home 25 years ago - built it and did the hvac. Geo thermal heat pump with a pond loop - all the math was done by water furnace with the spec provided by log manufacturer, man was that OFF. the electric back up [ resistance] heat was only to run on days below 6Fdegrees. More like 25F. that sucks even at .04 KW. Owner heats with wood - 20 years now in a fire place with a heat-a-lator. that thing sucks down wood, I talked him in to have air tight doors made and now it uses half the wood. sorry off topic the OWB could see some efficiency by a continuous burn, only because you have a cold fire and a cold HX when it comes off idle, the issue is it never gets hot even with a biggest fire. I don't think there is a practical retro fit for the OWB [poor design, fire in wrong spot] but I am pretty sure I could design one that is some where between OWB & Gasser technology That allows for a more friendly wood handling process.
  15. Duetech

    Duetech Minister of Fire

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    Another option is to replace the water level cap with one from Portage and Main (you know...? how they used to say it's time to replace the car by removing the radiator cap and drive a new car under it then replace the cap?) I recently bought a Portage and Main Optimizer 250 (gasifier with built in storage like an OWB) which is EPA Phase II white tag certified. Wood has to be seasoned but the unit sits outside like the OWB but puts out much more heat for the amount of wood used. This unit is so well insulated that snow will sit on top of it while idling or running full tilt (had some there for two days running now) but the wood should be kept covered. The home owner would still have the "throw and go" routine which is kin to using wood in an OWB but would get a lot more go for the time of throw and would probably take two years to use the amount of wood he is using in one now. He could try to sell his current model and get the P & M. Duetech (formerly Cave2k)

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