Monitoring Temp & RH in a Solar Kiln

[JackLeg]

What is anyone doing to monitor temperature and rh in their solar kiln.  I'd like to find something that will monitor inside and outside temp & rh and possibly allow downloading to my PC??  All suggestions welcomed. 

One caveat, I don't want to have to take a 2nd mortgage to pay for it!! :D

[brdmkr]

I have not used them, but several folks that I work with use HOBO monitors.  You may want to try a search.  They can also download to computer, and I don't think they cost all that much.

[solidwoods]

2 grocery store glass thermometers.
I drill a hole in a small board, slide the thermometers through (they have a glass flange at the top so now they are hanging).
1 gets a cotton shoe string and cup of water, the other gets nothing.
Wet bulb and dry bulb.

If your kiln has no fan or air circulation then you will get very different readings high vs. low in the kiln.

Multi wb/db are a good choice also.

Now monitoring is great,, how ya gonna control it?
jim

[JackLeg]

Thankis for the tips.  I went to Radio Shack and bought a simple indoor/outdoor temp/rh deal.. At least I can know what the temps are & humidity.   As for control, as the guys at VT told us, there is NO control.  Old Mother Nature is in firm control. 
:D

[solidwoods]

Now how much sense does it make to run a kiln without control?
Then what good would monitoring be if you have no control?

You let something else control your kiln operation and it needs to be responsible for the outcome.

Anybody reading that has ruined a kiln load?  Please speak up about what to do with a ruined load.

jim

[ronwood]

Jim,

I think if you build a solar kiln your chances of getting the load to hot or drying to fast is minimal if you follow the VT design. If you where to build a solar kiln like pineywood that would be different.

Ron

[Hokiemill]

Jackleg, sorry for the tardy response on this.  I'm now about two weeks into my first charge.  I probably have the exact same thermometer/hygrometer from Radioshack.  But what I've learned so far is that knowing your temp/humidity really is secondary information when it comes to controlling the kiln.  On sunny days, the temp is usually 100 to 120 and the humidity stays low 50% down to 20%.  Hard for me to use those constantly changing numbers to determine what I should do with the vents.  The information that I've really used is the daily moisture loss.  I try to weigh my kiln sample every day.  On good days, I've been consistently getting 2% loss a day which is fine for me with a load of oak.  Earlier I got 4% one day and decided to adjust the vents accordingly.  So, for right now, safe moisture loss rate rules all.

With all of that said, I was thinking like you and I wanted to document how the kiln performed for the website I'm putting together.  I bought a couple Lascar Electronics dataloggers.  They have a usb connection to directly attach them to a laptop for downloading.  The temp/humidity logger for inside the kiln cost about $85 while the temp only logger for outside of the kiln cost about $60.

[Larry]

The information that I've really used is the daily moisture loss.  I try to weigh my kiln sample every day.  On good days, I've been consistently getting 2% loss a day which is fine for me with a load of oak.

That's exactly what I found.  For a load of oak green off the saw I kept my vents just cracked to keep humidity high and slow the drying.  Once at 30% MC I opened the vents to dry as fast as possible down to 12%.  The water from 12% to 7% is the hardest to get out so I closed the vents to just a crack, to run the temperature up as high as possible.  During this part of the cycle the temperature will far exceed those in the first part of the cycle (assuming it is in the same season of the year).

BTW, you built a great looking kiln.  You should be happy with it.

[JackLeg]

Jim,

I think if you build a solar kiln your chances of getting the load to hot or drying to fast is minimal if you follow the VT design. If you where to build a solar kiln like pineywood that would be different.

Ron

I agree completely.  The VT design makes this thing about as "idiot proof" (that would be me) as it can get.  Dr. Bond at VT tells me he just shuts off the vents and lets her run. 

Monitoring is probably just a personal thing with me.  I wanted to see what kind of temps I'd be getting and the differences in the inside and outside RH.  I admit I have a ton to learn, but so far, I'm well pleased.

I checked the charge today with my MC meter and it's coming in around and just below 30%.  If we get sun for another week or so, I'm betting that that load of 7/4 cypress will be <20% and I can put in a load of 4/4.  I'm guessing, (guessing, mind you) that the 4/4 stuff will dry to <20% in 10 days IF we get sun.  We build outdoor furniture, so this thing will really help our drying times, and cypress is a VERY forgiving wood.  )Thank goodness!) 

Interested in everyone's posts on how your solar kilns are working.