my drying kiln for firewood and lumber

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We have a kiln setup with a Nyle DH4000. Looks to be the same as the 200, just and older model. (Kiln has been in place for ~15 years) It was put in for lumber, but I needed to get firewood dry for bundles faster than the usual air drying.

Decided to try using the kiln to see how it would work.

Was able to fit about 5 cords in bulk bags. (16 bags) Kiln is about 300sq ft. It took about 3 weeks to dry it, cost about $600 in electricity. (Might sound expensive, but I decided that having bundles, even if selling only at a slight profit was better than not having having and loosing customers)


Max temp on the kiln we have is pretty low. I think it can do 160*, but the dehumidifier will shut down on anything over 120* or so.

From what I've been reading, an actual firewood specific kiln goes around 200*. Apparently at those temps, they can dry a load of wood in just a few days.

Lumber needs to dry slow or it case hardens and splits, where firewood doesn't matter.
 
We have a kiln setup with a Nyle DH4000. Looks to be the same as the 200, just and older model. (Kiln has been in place for ~15 years) It was put in for lumber, but I needed to get firewood dry for bundles faster than the usual air drying.

Decided to try using the kiln to see how it would work.

Was able to fit about 5 cords in bulk bags. (16 bags) Kiln is about 300sq ft. It took about 3 weeks to dry it, cost about $600 in electricity. (Might sound expensive, but I decided that having bundles, even if selling only at a slight profit was better than not having having and loosing customers)


Max temp on the kiln we have is pretty low. I think it can do 160*, but the dehumidifier will shut down on anything over 120* or so.

From what I've been reading, an actual firewood specific kiln goes around 200*. Apparently at those temps, they can dry a load of wood in just a few days.

Lumber needs to dry slow or it case hardens and splits, where firewood doesn't matter.

Very clever. I've seen the pallets-on-rails on kilns elsewhere for side-loading instead of the big front-load doors, but not drawbridge. Why the drawbridge instead of hinge-mount conventional doors and an off-loading platform on the door apron of some kind?
 
2 cords?

How long did it take?

I'm modifying the kiln we use to be heated with a 100k btuindirect fired diesel heater.

The Nyle heater is only about 13k BTU. It's just too slow for firewood, I need the wood dry in 3-5 days, not 2+ weeks.

Also it's expensive to run being electricity is expensive here.

The idea is to feed the dry hot air through the wall of the kiln and exhaust the damp air out 2 vents near the ceiling.
 
2 cords?

How long did it take?

I'm modifying the kiln we use to be heated with a 100k btuindirect fired diesel heater.

The Nyle heater is only about 13k BTU. It's just too slow for firewood, I need the wood dry in 3-5 days, not 2+ weeks.

Also it's expensive to run being electricity is expensive here.

The idea is to feed the dry hot air through the wall of the kiln and exhaust the damp air out 2 vents near the ceiling.

The 2 cords was at 32ºF (might of been colder). DB started at 35ºF. 4 probes averaged 31% MC. It took 136.5 hrs to reach 20% MC. A little more than 5 days. A big primary baffle I had in place kept falling down inside the kiln so I figure that made it take a bit longer due to faulty air flow. It took 530 kWhrs so you can do the math on that for elec costs in your area. I thought it was quite reasonable. Prices here are CAD$0.15805.

This second batch I have in now is right on track with its stats when comparing to previous load. Only thing I am doing different this time is I turned off the heating element after the DB reached 120º. Its been running for 24 hrs now and the DB has been able to maintain the temp about 118-119. For the last 24 hrs its been dumping 250 ml every 2-1/2 minutes.

I've looked at other setups, even larger setups, and dedicated ones as well just for firewood. Increased capital costs I think outweigh the flexibility of the L200M we have. When I don't have firewood in it, I can use it for lumber. If sales got to the point where I need something bigger, I'd seriously consider getting another L200M. When the time comes, it will be easier to sell off something like that, than a dedicated firewood kiln.

The next few loads I will be doing, I am going to experiments with different stacking methods to see if improving airflow can shorten the cycle.
 
Our kiln is setup pretty much like yours, using the Woodmizer plans. I think it's bigger though, as I fit about 4.5 cords (15 super sacks). It measures about 18x22 I believe. I might be a little off on that, I've got it full of wood and running right now so can't go measure. Ceiling is tapered, about 12ft tall at the high end, 10ft at the low end.

The last load I did, it was anywhere from -15* outside to 30*. The wood was frozen for sure.

Though I did a load this fall when it was in the 40s-50s and it didn't seem to take that much less time. I think the power bill for that load was maybe $100 less than the winter load.

I'm not sure the hours of run time on the last batch, I'd guess in the 375-400 hour area. It took about 3000 kw/hr, or roughly $600.

Sounds like your controller setup is a bit more fancy. Ours just have a temp and humidity readout and the ability to adjust each. The humidity is a guess at best really. I trusted it on the first load I did and ended up with popcorn fart dry wood, even though it was still reading in the high 20s. The wood was 8-12%

After that load, I got a remote probe that goes in the wood and I just wired it to outside the door. Plug in the moisture meter to get a reading.

I did not expect the seasoned wood to sell that well...I had air dried about 12 cords figuring that I might end up getting "stuck" with it.
Well... that sold before the weather even turned cold!
I had not really planned on using the kiln, it was mostly a plan C type thing.

Now, I'm thinking to not really deal with air drying the wood. The state changed their rules and I can't consider it seasoned unless it's been drying for at least 8 months.

I know the wood is no joke dry with the kiln, where air drying really depends on the weather. A cool rainy summer would not do much for drying vs like last summer was hot and very dry. (I got lucky for that)


I know a few other people have written about the Nyle 200 style kiln and I know a few have added heaters, as the stock heater isn't that much.
Once the wood is up to temp, it stays there for a long time, but it takes forever to get up to 120-125*.
I fired it up on the 28th and it was only at 60* when I checked it last night, so around 72hrs.

Anyhow.. great to fire off ideas with someone that has an idea of the kiln setup. I've asked a few times on forums and I get crickets, or people trying to argue that it makes no sense to dry wood like this.
 
I have no complaints about the ability of the L220M bringing the firewood up to temp. For this batch that is in now, from a starting point of 32ºF the DB and WB get up to nearly 120ºF in 36hrs having consumed 242.2 kWHrs. That's about CAD$38 (US$28). And that's with outdoor temps around 24ºF.

If the split wood can be air dried for even a month or so, that will lessen time in the kiln. I will be experimenting with green wood though, just to see how long it takes.

Orientation of the split wood I think plays a roll as well. The two runs I've done so far have been about the same. The next one I will change how the wood is stacked on the pallets. Again, just an experiment to see if the kiln time can be cut down. Improved air flow surely can play a roll.
 
It took well over triple that in power to get to 125* on our kiln. And about 5 days.
I'd need the wood dry by then.
 
Also I don't stack the wood in the kiln. That would add easily an extra 7-8 hours of labor, if not more time.

I fill FIBC bags off the conveyor and forklift them to the kiln, then use a pallet jack to get them positioned in the kiln.

I suppose it'd be able to fit more in the kiln then, but I don't think it'd speed things up much... IE if it takes 14-18 days to dry ~4 cords, it'd likely take ~30 days to dry 8 cords.
 
If your FIBC bags were 1' - 2' off the floor, would it increase air flow in the kiln?
I still had snow between the pallets, and they were frozen to the ground. That may not be true since we had a long steady rain last week, and I've not checked in several days.
Edit: The point being, even with the wood on pallets there is little air circulation near the ground. Last year the wood seasoned poorly compared to previous years.
 
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