Holz Haufen Update

[Todd]

Well it's been 3 months since I built my 2nd HH with fresh cut and split Oak. It looks dry from the outside, lot's of radial cracks and the wood color is darkening. I took a moisture reading from my cheap $20 meter, and the outside was averaging 12% to 15%. I cut a piece in half and it pegged the meter at 35%. You could see the moisuter leeking out the holes from the meter. I haven't burned any of this wood yet, but I bet it's still not ready. So I think that 3 month dry time for a HH is wishfull thinking. Maybe 6 months? I'll keep you posted.

 

[Eric Johnson]

I've been thinking about the HH and comparing it in my mind to a conventional, "straight" pile. In my case, it's a series of straight piles with about 8 inches in between.

What happen in my piles (I surmise) is that as the pile heats up in the sun, you get a chimney effect in the gaps between the piles. As the hot air rises, it create draft along the ends of the pieces of wood, and from the spaces between the chunks, drawing moisture out of the pieceds of wood. As this air warms and moves up and away from the pile, it is carrying the moisture away with it. With straight channels of air like this, the chimney effect must get going pretty well. On a hot day, I suspect it's convecting mosisure away from the stacks to at a pretty adequate rate.

Thinking about the HH, on the other hand, there is no clear air pathway to move moist air out of the pile. It has to wind its way around voids wherever it can find them. In some places, there may not be any.

Seems to me that a conventional stack of series of stacks is better equipped to move large amounts of moisture away from the wood on a regular basis. I fail to see how the HH can achieve comparable results, much less be more effective.

The bottom line is that it takes about a year to completely "air-dry" firewood under most conditions. I'd be surprised if the HH can do it any more quickly.

 

[Mo Heat]

... I fail to see how the HH can achieve comparable results, much less be more effective.

... I'd be surprised if the HH can do it any more quickly.

Eric, I think you've been parenting too long. Holz Hau[sf]ens look cool. Even if they don't work.

I believe (for reasons I have explained elsewhere) that a HH may well be able to dry wood a little faster than (or at least as fast as) rows. But certainly not in just 3 months, and I think this is being born out by those of us who have built them (like Todd and me). Although I don't think any of us actually believed it was possible or even probable to see such accelerated drying as a couple places claimed.

I doubt anyone will ever be able to prove whether rows or HH work better. At least not to any objective degree. But I feel like I have a work of art in my back yard. Hopefully it won't fall over like my rows often do. There's a lot of wood in that sucker. If it does fall over, I'll rebuild it. I don't think I did a very good job on the foundation of my first HH and I built it on a hill. I'm actually a little surprised it's still standing.

 

[BrotherBart]

Don't know how much convecting is going on in my BartsHaufen "standard" row stacks. After I read hearth.com for a while and discovered the science of the wood pile I dropped a remote temperature probe down 2/3 to the bottom of one of the middle inside rows. The inside stays consistently 11 degrees cooler than the outside of the stacks. At the moment it is 88 degrees ambient outside, on top of the stacks it is 84 degrees and down inside is 73. Maybe the convection is cooling it?

 

[Eric Johnson]

Your HH does look pretty sharp, MO.

Walk past my woodpile on a hot summer day, Bart, and it's noticeably cooler. I can only conclude that's a result of the evaporation.

People get confused about wood drying because most wood will check and dry out on the ends almost immediately (even in the winter). They don't realize (or choose to ignore the fact) that there's a lot more to the wood than the ends.

It takes about a year to air dry firewood if you've stacked it correctly. That's my mantra, and I'm sticking with it.