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when/why is humidification required?

Started by Raym, April 15, 2015, 08:30:27 AM

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Raym

I have a Nyle L200m dehumidification kiln and recently installed a secondary heat exchanger (hot water coil from my OWH) to replace the 4kw heat strips. If I have the need to dry small specialty loads or thick slabs is a humidification system necessary?
'14-LT40 super, nyle l200m kiln, vintage case 480E loader.

It's not the fool that askith, it's the fool that agreeith.

beenthere

Do you plan to control humidity some other way?
Or not feeling it necessary to have more control of the humidity?

What is your drying schedule like?
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Raym

Quote from: beenthere on April 15, 2015, 01:07:42 PM
Do you plan to control humidity some other way?
Or not feeling it necessary to have more control of the humidity?

What is your drying schedule like?
Here are my issues, keep in mind I am still learning. At the beginning of a cycle with a small load, with the dry bulb setting low (90) and the wet bulb setting high (85), the controller is calling for humidification. I am guessing this is because there is not enough moisture in the green wood to obtain the high wetbulb reading and I would imagine that it would be worse in the winter months when the outside air is already dry.
'14-LT40 super, nyle l200m kiln, vintage case 480E loader.

It's not the fool that askith, it's the fool that agreeith.

beenthere

That helps.

There is a kiln drying manual that has several chapters that might give you a leg up on how to meet the need for higher humidity.
http://www.fpl.fs.fed.us/products/publications/several_pubs.php?grouping_id=101&header_id=p

Off the top of my head, lowering the dry bulb temp a few degrees may help as it sounds like you need to meet the "demand" for more humidity.
Might even hose the floor down to get some humidity, or zero in on the settings you are using at this stage of your drying schedule.

There are more and better experts on the forum who likely will chime in soon.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

red oaks lumber

no need for humidifcation. close the gap on the w.b.--d.b. if your worried about drying to fast slow the cycle times on your compressor, also raising your kiln temp will release more moisture.
if your still having issues,disconect the sensors :) iv'e dried hundreds of thousands of b.f. using l200 without the fancy sensor dudads :) sorry i'm not a big fan of technoligy
the experts think i do things wrong
over 18 million b.f. processed and 7341 happy customers i disagree

GeneWengert-WoodDoc

The humidity is how we control the rate of drying.  The rate determines the quality of the dried product.  Most important is the rate above 40% MC, as that is when almost all quality is determined.

So, with well air dried wood going into the kiln, the humidity control in the kiln is not critical, except to prevent over-drying.

For more detailed explanation, see DRYING HARDWOOD LUMBER and the four stages of drying.

Note that velocity and temperature are the other two environmental variables that control quality.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

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