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Holz Hausen Experiment - Results are IN!!

Post in 'The Wood Shed' started by Apprentice_GM, Aug 27, 2008.

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  1. Apprentice_GM

    Apprentice_GM Member

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    *** The results are (finally) in and the winner is Standard Ricks. More details on page 4 of this thread or you can click through to my blog with results and experiment data here ***

    G'day All,

    Having accumulated enough wood for a Holz Hausen and having been keen to build one ever since I discovered them a couple of months ago, I plan on commencing my splitting and holz hausen stacking early spring (in the next few weeks - check my location if this doesn't make sense) and I was planning on measuring and determining some differences between a HH and a regular stack.

    Before I begin though I thought I'd ask and see what everyone would like me to do in the way of measuring and experimenting. My primary reason is to validate or refute the claim it can season wood in 3 months, or up to 8 times faster than a normal stacked row. Here is what I was planning on doing:

    1) Build an approx 8' diameter and height HH. Clear and level a spot with good northern exposure (sunny) and decent airflow. Put some treated pine timber down to raise the HH off ground a little (prevent it becoming a snake house). I might get a bit engineery with the platform/base so it will last for years if the HH proves a success and I keep building them. I plan on marking the centre pole every 2 inches / 50mm or so.

    2) Split my timber and set aside 36 pieces. The 36 pieces will be 3 different timber types (probably 2 x hardwoods eg bluegum, turpentine or yellow stringy bark and 1 x softwood eg conifer) of 3 different sizes (small eg 1/4 of a 6" round, medium eg 1/4 of 10"-12" round and large eg 1/4 of 16" round) each of 4 pieces. These will go in the bottom, middle and top of the HH at each point of the compass.
    Each piece will be moisture-meter tested, weighed, measured and recorded after splitting. These measurements will then be used to determine how well each piece in the pile has seasoned over time, and whether pieces on the northern (sunny) side season much faster or negligibly faster, and whether height in the pile makes any difference (eg higher might get more airflow).

    3) I hope to find some scrap pieces of pvc pipe to put some additional constant measure pieces into in the HH. This will allow easy removal and re-insertion of constant measure pieces for constant measuring, and I can compare their end progress with the other 36 pieces, to gauge whether the PVC pipe surround has artificially helped or hurt their seasoning (ie extra space around the wood might help season it slightly faster. or not).

    4) I have ordered a cheap moisture meter, and a weather station which logs temps/humidity/barometric pressure/rainfall/wind speed and direction to my PC. This will allow me to build an automated Excel spreadsheet to both calculate averages during seasoning and allow others to guesstimate their seasoning progress based on my results. I will log everything in metric but it shouldn't be too hard to convert to imperial :)

    5) I will take weekly pics of the HH and post in the forum thread for "progress" along with some initial measurements.

    6) I plan on building 2 small rows of wood, one running east-west and the other north-south, nearby, and placing some pieces in them also measured as above, to use to compare with the HH at the end of the experiment.

    Any suggestions or requests? :)

    I haven't seen any posts here that verify or refute the HH claim to dramatically superior seasoning, and I reckon it's in all of our interests to resolve this. I for one am dirt curious!

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  2. Adios Pantalones

    Adios Pantalones Minister of Fire

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    well- if you're going to have specific pieces to measure- you may be better off weighing them. A moisture meter will mean that you have to split them every time you want to measure the internal 'true' %mc. If you weigh some, then dry similar pieces in the oven or measure several with a moisture meter- then you can estimate starting %mc, and monitor the others just by weighing them.
  3. Apprentice_GM

    Apprentice_GM Member

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    Yep, I am going to weigh them AP (#2 above) in the beginning and end and those constant measurement pieces, er constantly throughout :)

    I was also going to use the moisture meter at the start and the end in addition to weighing them. At the end I might split them again so as to measure the middle of the pieces moisture content more accurately.
  4. Adios Pantalones

    Adios Pantalones Minister of Fire

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    There were all these words and so I got confused and distra... hey look- a quarter!
  5. Apprentice_GM

    Apprentice_GM Member

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    ROFLMAO

    Yeah, I get a little detail-oriented sometimes, it's the engineer in me (choleric/melancholic for those that know the temperaments) but I did read a monster detailed post of yours recently regarding a kiln Q and A :) Just out of interest, is that you in that avatar? Not the cartoon dude, the one with the paintbrush?
  6. Adios Pantalones

    Adios Pantalones Minister of Fire

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    No- that's Bob Ross- had a painting show on TV for years- had a very recognizable voice and was too mellow. Look him up on Youtube for a couple laughs.

    I know what you mean about detail- I put the "anal" in "analytical chemist" LOL
  7. Todd

    Todd Minister of Fire

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    I did a test two years ago with the straight rows vs HH. Don't waste your time and energy, there is no difference in drying times. The main advantage of the HH is it's real cool looking and you can stack alot of wood in a little space. Either method will still take 6-12 months for hardwood to dry, best to get 1 or more years supply so your ahead of the game.
  8. archer292

    archer292 New Member

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    I stacked in HH configuration at the end of last burning season. I had all intentions of weighing and measuring and everything else so i could make a fair comparison of my own. I wound up stacking 3 holz hausens in the yard but had no wood or room or patience left for conventional stacks. Anyway, my location and yard size dictated where i could make the HHs. I put them in the sunniest spots working around the kids play set and everything else. I split some pieces today and used a moisture meter to check. NONE of the wood will be ready to burn this year. The moisture readings were anywhere from 36% to over 50%. The meter is rated to 44% so I have no idea how accurate it is after that. The HHs are 7ft by 7ft and have been split and stacked for 5 to 6 months. NO it did not work in my situation. Maybe its the location of the stacks, maybe I should have covered them instead of using the bark facing up at the top, maybe all the pieces should have been stacked with the bark up, who knows.... All I can say is it DID NOT WORK!!!!! and I definitely have had them stacked for more than three months. Maybe in the perfect situation or should I say location, the HH would work but not here and not for me. It is still a good way to get a lot of wood in a small area but not for faster drying. They look good, but are hard to build. The worst part of this is that I have no seasoned wood to burn!!!!! Yet again. Well, I have wood for next season, I hope.
  9. archer292

    archer292 New Member

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    I must have posted twice.
  10. Adios Pantalones

    Adios Pantalones Minister of Fire

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    What do you mean it did not work? Were you under the impression that it would dry in half the normal time? Most wood normally takes about a year to dry properly.

    BTW- has it been super rainy this summer for you? That definitely effects drying times.
  11. Todd

    Todd Minister of Fire

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    There are claims that an HH will dry your wood in as little as 3 months due to the chimney effect it creates. I found no difference in dry times between it and straight rows.
  12. archer292

    archer292 New Member

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    I didn't know what to expect. It has been stated that the wood in an HH will season in as little as 3 months. With that, it did not work. We did have a lot of rain this summer, maybe that was it. Either way the HH will hold lots of wood in a small space, but that to me is the only advantage.
  13. Adios Pantalones

    Adios Pantalones Minister of Fire

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    3 months! never heard that claim- I have read the claim of "quicker", but I have doubts about that.

    As for gravity draining the logs- unless you see water dripping out of them, and you won't, I doubt it would be an effect. I guess if water concentrated in one end, then it would evaporate quicker, but that would only happen until the bulk water was released- not more than a couple weeks.
  14. Adios Pantalones

    Adios Pantalones Minister of Fire

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    By the way- try it with white ash or white birch- it may be ready in as little as 3 months (holz or not LOL)
  15. archer292

    archer292 New Member

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    As little as 3 months was exactly the claim. Search it!!!!!!
  16. Adios Pantalones

    Adios Pantalones Minister of Fire

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    Hey- I believe that someone made the claim, I just don't believe that it would work (unless it was thin split wood that seasons so quickly anyway). I like the holz stack because of space saving and it looks cool.
  17. pybyr

    pybyr Minister of Fire

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    This is a really interesting experiment and I'll look forward to following the objective data. I built my first Holz in 2006, and another one last year, and based on what I saw, I am on the fence as to how well they work compared to other methods of stacking and drying

    One downside was that in each case, despite using level and stable ground (and in the 2007 incarnation using shipping pallets as a base to get the lowest levels off the soil) in each instance, as the wood dried and shrank unevenly (despite my having built it carefully), my HH-es shifted, and eventually avalanche-ed-sideways- and when they did, it was a formidable release of force in a very short interval.

    So I would definitely be cautious about building an HH in a location where kids might end up playing on it or next to it (including unauthorized or unexpected kids who may wander near it). For that matter, keep any valued inanimate objects out of an HH's potential tumble zone, too.
  18. Rockey

    Rockey Minister of Fire

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    The only way i could see a HH being more effective at drying times is to do the following. Make a tarp the covers all but the 1st foot of wood from the ground up. cut a hole in the top of the stack and tape a large square fan to it so the air is directed up and away from the HH. Theoreticly it would draw air in throught the bottom, through the stack and out the top. Without this aid the only chimney effect would come from Delta T which I doubt would be very efective. I built my HH out of seasoned wood
  19. pybyr

    pybyr Minister of Fire

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    You are all mere amateurs in that regard unless you've wondered and worried about whether use of an italic type text font achieves, or should achieve, italicization of the period at the end of the italicized sentence. I once had to interact with a well-credentialed professional who actually devoted serious thought and discussion to that...
  20. pybyr

    pybyr Minister of Fire

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    I once got thinking about trying to use a moderately large-diameter piece of highly- perforated PVC or polyethylene drain pipe at the center of an HH, with a chimney-type rain cap on top, so that air could convect up and through the middle better than the old/original type HH.

    This idea was based on my sense, after my 2006 and 07 HH's had tumbled after several months, that the innermost pieces had seasoned considerably less well than the outer pieces (my HH's were 7-a ft diameter and roughly 6-7 ft tall at the peak. My hope was that the perforated center chimney might help air flow more evenly through the whole thing, and create an exposed "drying edge" in the middle as well as around the perimeter

    Or better still- maybe?- one of those air-powered spinning ventilators on top of the center pipe, such as you see on agricultural or industrial buildings.

    Never got around to bothering with this "center chimney HH" idea, and don't know if/when I will, but thought I'd throw the idea out
  21. Apprentice_GM

    Apprentice_GM Member

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    Regarding previous comments:

    1) I have read the claim that an HH seasons in as little as 3 months. It's stated in this chimneysweep article I read.

    2) If an HH does not accelerate seasoning then I wonder why so many throughout Europe, who have trouble seasoning wood due to cold and wet climates (certainly compared to Oz) continue to take the trouble to build them. I doubt so many enjoy the aesthetics and efficient storage benefits compared to the time spent building them over normal rows, I would suspect function (faster seasoning) plays a part.

    3) I would be interested whether previous poster who built an HH and compared to normal rows did lots of testing throughout, as if a normal row could season enough in 12 months then perhaps the HH was seasoned in half or a quarter of that. Not rejecting his findings, just want to know more, especially about the testing method. If he did something like I plan on doing, and came up with that result, then that would discourage me from wasting my time - I'm under no illusions there will be a few hours invested in this.

    4) For the poster who stated his HH didn't season the wood at all, did you leave plenty of gaps for airflow? How large were the pieces? What were the weather conditions throughout?

    5) As for chimney accelerators, I have also thought about some. My first thought was to create a spiral pole, allowing the uplifting air to spin around the pole hopefully accelerating like the tornado effect. My second though was to get some PVc and heavily perforate it, but I have decided they may be worthwhile options to test later, after the basic HH is compared to rows.

    6) I don't think the tarp suggestion is a good one. The idea of an HH is to draw air over all the splits towards centre, then up and out like a chimney. Covering most of the stack prevents this, prevents air being drawn over and along the covered split.

    7) I don't think the idea behind an HH's supposed faster seasoning is a temp increase in the pile, I think it has to do with airflow advantages as per above. Perhaps I can do some testing here by placing a thermometer in the pile which reports back temp compared to normal outside air?

    8) Perhaps I can do smoke testing around the pile and see if air gets drawn in and up as per my theory (or at least other's theories on why HH's are better)?

    9) I have thought about containing the HH and I think wrapping some chicken wire around it and wire twisting it together, or stapling it to pile, will prevent pile collapse but allow airflow and sun drying pretty much unimpeded. My son runs around the yard and preventing him running right there at all times will be difficult (I could put some tape across pegs, that would stop him, he's very obedient that way).

    So, what do you think? Should I proceed with this? I haven't found any other similar experiment posted anywhere . . . save me time if it is . . . do we want to decide this (at least in my weather conditions) or not?
  22. Rockey

    Rockey Minister of Fire

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    6 - Tell me, what exactly do you think is going to draw the air in to the center of the HH? Trust me, every split in the center of the HH is going to be colder and receive dramatically less airflow than the splits on the outside of the HH without the aid of a fan.
  23. iceman

    iceman Minister of Fire

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    one thing i am convinced on.... doesn't really matter what kind of stack but HOW you stack...etc single rows with spaces inthe same environment as hh WILL season just as fast .... when you stack with space either by row or loosely stacked will season good the key to hh is to get airflow in a small area.. many of us that stack 10 rows tight that is the wood that will take longest as it hardest to get airflow through....also sun and wind is good ...great but YOUR location is everything.... here in the NE i am sold on the 1-2 years to season yes... but our summers are usually hazy hot humid which the wood will not lose as much mositure if we were in texas or arizona ..someplace where its always sunny and DRY (not humid)... wood gets its most seasoning here in the ne in the fall as we have much drier days humidity wise which allows more water to evaporate. even more so with our dry winters.. from usually nov on we get dry dry air which is the key to evaporation..
    so in summary : the method of stacking is not as important ...its how you stack it and your climate
  24. sgcsalsero

    sgcsalsero Feeling the Heat

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    I think your endeavor is worth it and many here at the forum would probably check out a blog if you track weekly/monthly progress.

    I have three HHs built and enjoyed building every one. I laid two courses of brick staggered as a base on the last one to encourage airflow and chimney effect, I may try a smoke test like you suggested, but I wouldn't be surprised if the draw wasn't that much. I don't care about making things tight or filling gaps, I used a lot of shims to keep the angles correct which created pockets. I do try to stack upright as much as possible in the middle (rather than just lazy-like tossing stuff in middle which could cut off airflow). I wouldn't make my HHs larger than 6-7 foot wide, more smaller ones to me seem to make sense (again the more airflow and sun the better). I agree that the Europeans (Holz Haufen is German after all) would have chucked the idea of these a few hundred years ago if they didn't work. One thing I need to work on is a better methdology on creating a shingled roof to shed as much rain water as possible. One thing you may want to note is how dry your wood in HH remains even after a decent rain.

    Anyway, great to hear from down under and good luck, I'll probably end up posting a couple pics of mine in the next weeks.
  25. Apprentice_GM

    Apprentice_GM Member

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    Well, I think it's simple, but obviously yet to prove it. My contention is the thing which seasons a HH faster than normal stacks is increased airflow (there is no doubt that increased airflow seasons much faster so it is reasonable to assume that this is the main reason for a HH). Your question is why?

    Airflow, even very light winds, flow around the HH and over the top. When the top is shaped like a dome or pyramid/cone it creates low pressure at the centre - just like a wing (of a plane, chopper blade etc) and this draws air up the middle, or up the chimney. This air has to come from somewhere, as it in turn creates a low pressure zone in the middle of HH. The air then comes from outside the HH, flowing along the splits. That is the main point, and I know it's my theory not some learned scientists - well I haven't seen it elsewhere - and I have another, additional theory.

    Airflow around the side of the HH creates similar low pressure points, again like a wing, or like a boat at mooring (this is why 2 yachts accelerate towards each other on moorings and bang into each other - benefit of a catamaran but that's a different topic). So airflow is increased even without the top or chimney effect. In other words, my contention is if you built a cylinder of wood up to a ceiling, so air flows around sides but can't flow over the top, you would still get an increase in airflow across the splits compared to traditional rows or stacks. A poster in another HH thread here postulated similar thoughts for this point, but didn't or couldn't try to prove it.
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