solar kiln question

Dulowry · March 10, 2015, 10:33:45 PM

Hello new to kilns and this site and I'm looking for advice. I'm making plans for a VA tech. Type kiln the question I have is. Is it better to have your fans run off of a timer ( based on sun up sun down) or is it better to have them hooked to a thermostat? Also any suggestion on the best m/c tester what is a good one for the price ? Thanks for any help.

pineywoods · March 10, 2015, 10:38:51 PM

I leave um running 24/7 until the lumber is dry. If you stick a de-humidifier in there, you usually want it to run at night and shut down during the day...

Dulowry · March 10, 2015, 11:16:59 PM

Thanks for the help If I run a dehumidifier with fans on 24 7 and start with green fresh sawn lumber what is the risk of drying too fast I live in stl mo if that helps

GeneWengert-WoodDoc · March 11, 2015, 11:21:35 PM

The fans in the VT solar kiln are run only during daylight...about two hours after sunrise to two hours after sunset. basically, you run them when there is heat. A times is perfect and is what I used when I first developed the kiln and ran it with a timer for years. If you run the fans 24 hours, you will be unable to dry under 11% MC in the VT solar kiln. The high humidity at night keeps you from achieving the low MCs. Running the fans during daylight also saves energy. Note that the high humidity at night relieves drying stress, also called casehardening stress.

As far as a moisture meter, plan to spend over $200 and get one that is made in the USA. You can get a pin type or pinless type, but for a kiln, the pin meter with insulated needles is more useful. However, appreciate that any meter does not work well above 28% MC.

Dulowry · March 12, 2015, 09:12:31 PM

THANKS WOOD DOC FOR THE HELP IF I WERE TO USE A DE HUMIDIFIER IN THE LATER STAGES SAY WHEN WOOD IS UNDER 20% MC IS 8 TO 9 % POSSIBLE IN A VTEC TYPE KILN?

Dulowry · March 12, 2015, 09:14:50 PM

One more question I am following a plan 160x 78 at the base should hold 800 bf of 4/4 plans show 8 vents 6x14 should those remain open all the time?

GeneWengert-WoodDoc · March 13, 2015, 07:39:24 AM

The VT kiln will achieve 7% MC without a DH. A DH would be faster and will require electricity, so the higher speed is not free.

The vents, at the end of drying, are kept almost completely closed to allow for good heating. At the beginning, the vents are kept nearly closed to prevent rapid drying, if required by the species. They seldom would be completely open, so they do need doors. Ok?

Tree Dan · March 13, 2015, 10:13:24 AM

Quote from: GeneWengert-WoodDoc on March 13, 2015, 07:39:24 AM
The VT kiln will achieve 7% MC without a DH. A DH would be faster and will require electricity, so they higher speed is not free.

The vents, at the end of drying, are kept almost completely closed to allow for good heating. At the beginning, the vents are kept nearly closed to prevent rapid drying, if required by the species.m they seldom would be completely open, so they do need doors. Ok?

Hi Gene,

What part of the cycle would the vents be open the most for

Hard maple:

For Pine:

Thanks

GeneWengert-WoodDoc · March 14, 2015, 07:55:12 AM

The key for HM is to achieve the correct RH at all costs. The vents would be partly opened in the VT kiln with a full load right from the start therefore. After the first week of good drying weather, they would continue to be open but you might begin to close them slightly to get more heating, but still avoid high RH. The vents are too large to open fully for most species except pine and poplar, mainly.