iDRY Vacuum Kilns

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Cold Weather Solar

Started by tacks Y, February 05, 2020, 04:48:38 PM

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tacks Y

It was in the low 30s today and kiln was 80-85 degrees with fans on. Am I wasting electric running fans like this? Or will some drying take place?

doc henderson

this is a solar kiln.  what is the relative humidity in the kiln.  prob. very low.  what is the moisture content of the wood that is drying?  under 20% the fans do less.  better than outside since as the temp drops outside the RH goes up.  @GeneWengert-WoodDoc  so think of it being 30 or 80° outside air drying.  it is better than nothing.  i do not recall the cost to run a fan, but it was recently posted by Dr. Wengert.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

farmfromkansas

We had cloudy skies today, so no heat in my wood dryer.  Now that the sun is rising in the sky, won't be long till it is at 45 degrees, and my solar panels will be getting really hot on sunny days.   Interested to see how hot my reefer gets inside, first full season.
Most everything I enjoy doing turns out to be work

tacks Y

I do not read RH in kiln, should I? Wood is quarter sawn red oak and sycamore at 9-10 percent. I have read the 20 degrees over outside so well above that.

doc henderson

I would want to know the wood MC to see where you are in the schedule.  with oak you do not want the gradient from the wood to air to be to great and cause checking.  so you need to know the RH of the air in the kiln, also represented by the difference in dry bulb (actual air temp) and wet bulb (depression of the actual temp on thermometer covered with moist cloth).  the dryer it is in the kiln (lower RH)  the more the water will cool the wet bulb thermometer.  like sweating on a dry day feels cooler than on a humid day.  as dry as the lumber is, you should be ok.  What is your goal final MC for the wood.  I think @GeneWengert-WoodDoc  has stated that an increase of temp inside relative to outside of 15° is needed to drop humidity enough to promote drying.  fans are cheap to operate with free heat (sun).  good luck.  if we keep talking about it, the wood should be dry! :D :D :D
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

farmfromkansas

Did not get my reefer solar wood dryer finished and loaded till late Sept, and put air dryed lumber in it at that time, took some out last week, tested it with my mini ligno, and it tests at 7%.  Hope that is accurate as I planed a bunch of it.
Most everything I enjoy doing turns out to be work

scsmith42

Quote from: tacks Y on February 05, 2020, 04:48:38 PM
It was in the low 30s today and kiln was 80-85 degrees with fans on. Am I wasting electric running fans like this? Or will some drying take place?
Lumber will definitely dry at 80 degrees plus in a solar kiln.  You're not wasting $.  You might want to put a timer or temp controller on the kiln to cause the fans to kick on when the temp is about 70 inside the kiln.  Also to shut the fans down if the RH% gets below 20%.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

tacks Y

After reading comments about RH in kiln I put a gauge in. It has been 20s-40 degrees outside last week no sun. Started at 50%, today some early sun then clouded up again temp made it to 55 in the kiln and humidity dropped to 36.  Left fans off till more sun shines. At 9-10% moisture in my 4 quarter wood, what do I need to see for humidity to have wood drying?

doc henderson

does the gauge tell you max. and min. RH and temp inside and outside.  I think no matter what, this is better than being outside.  I would check the MC in the wood at least every week, to see that it is stable or dropping.  not as much happening in a solar kiln in the winter.  just keeping it out of the rain, and super humid days, is a start.  My $14 accurite, can be looked at daily and record all that data in a notebook, or ledger in a computer.  I have a container of wood.  humidifier is off the past 2 months, and the wood is stable since it is dry and the container is sealed up.  I watch it on that thermometer.  the sensor push that @YellowHammer   likes can log that data for collection and graphing on your phone via app.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

scsmith42

Quote from: tacks Y on February 12, 2020, 03:59:00 PM
After reading comments about RH in kiln I put a gauge in. It has been 20s-40 degrees outside last week no sun. Started at 50%, today some early sun then clouded up again temp made it to 55 in the kiln and humidity dropped to 36.  Left fans off till more sun shines. At 9-10% moisture in my 4 quarter wood, what do I need to see for humidity to have wood drying?
You need to "see" an auxiliary form of heat!
Lumber does not dry much at 55f
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

doc henderson

do you have electricity.  many here have added halogen work lights.  make sure you have a safe place.  it will take some juice.  you have fans so up to you if you want to speed it up.  or a wood stove ect.  the trouble is the solar roof will loose a lot if the heat.  waste wood not a big deal, electricity or NG/propane will cost more and the heat will go out through the roof panel.  For a heated kiln, you need all 6 sides of the kiln to be insulated.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

GeneWengert-WoodDoc

In general, we can run the fans and get drying when the tenperature is 15 F warmer inside. 20 F warmer is even better, in general.

To be specific, we need to know the species, thickness and MC average (not core).

You do not need an RH meter, but it can be fun to look at now and then.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

tacks Y

doc and scsmith, not in a hurry so will wait for more sun. I just did not run fans for nothing. When the temp gets 80 or above we will go back at it.

Gene, What is meant by thick essays? Kiln has red oak and sycamore in it now.

I have been cutting birch blk&yel. Hope to cut and skid blk gum and gray elm out in the am. Saw as weather gets above 40 degrees.  Stacking and covering to start air drying. 

doc henderson

It can set for now as long as the RH does not get too high.  low MC in the wood so no mold ect. what kind of moisture meter are you using, or are you doing oven dry method.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

GeneWengert-WoodDoc

I corrected the error.  I had my knee replaced so some posts are not so good.

In terms of temperature, 50 F is the minimum.  But if 50 F occurs first thing in the morning, chances are good that the humidity inside and outside is really high.  So, we wait until the temperature difference, inside to outside is 20 F roughly.  This will happen when there is sun power coming into the kiln.  Or, you can just run on the basis of time...9AM to 6PM or similar.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

doc henderson

@GeneWengert-WoodDoc  I plan on seeing you at the sawing project 2020 in Georgia.  Do you have any formal Kiln classes near me coming up on basic and or advanced Kiln drying technique?  I really enjoy the topic and your presentation of it.  thanks!  Best Regards.
I hope soon I can invite you here and maybe build a solar kiln.  the one class in Virginia fell through and I have heard nothing more about it.  
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

GeneWengert-WoodDoc

Basic Drying Class.  The NHLA is sponsoring a Basic Class, May 4-6.  I am the Instructor.  I enjoy teaching, and try to be very practical.

Advanced Drying Class.  This will follow the Basic Class, May 6-7.  Again,,I am the instructor..

Both classes are in Memphis.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

doc henderson

Thanks for the information.  we can talk more in April.  we are considering getting another property to move the mill and equipment to.  has a cabin, and pond with tons of fish.  if so, we will plan to build a solar kiln, and poss. add a DH later as well.  75 acres and would be a nice place for a future FF get together.  prob. still a year out, but might see if there would be interest. 
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

farmfromkansas

Doc, what a great idea.  Also plan a solar kiln, been debating a large rear door vs a 36" walk in door.  The walk in door would be much easier to seal, but a lot harder to load.
Most everything I enjoy doing turns out to be work

scsmith42

Quote from: farmfromkansas on February 14, 2020, 09:52:42 AM
Doc, what a great idea.  Also plan a solar kiln, been debating a large rear door vs a 36" walk in door.  The walk in door would be much easier to seal, but a lot harder to load.
I'd advise you to follow the Virginia Tech design.  Well thought out and very practical.
End loading a kiln through a 36" door is a major pain.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

tacks Y

Kansas, I put a 50 something door on mine to push a cart in. And a 30" to walk in. Pics should be on my profile. Happy with mine to load.

tacks Y

Ok -5 here this morning w/sun. At 1pm it was 90 in the kiln with an RH of 18. Turn fans on for a couple hours, clouds move in temp has dropped to 70 and RH 40. Turn fans off. 5pm 60 inside and RH 38.  This make sense? Vents open 3/4".

doc henderson

at 90 you pulled some water out, and when the temp dropped you saw a rise in RH.  can you check wood MC in a week or so and see if it is dropping.  maybe put the fans on a temp. switch.  if it was sealed tight with no vents, the humidity would have been higher at 60°.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

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