We pre-dry our lumber to 12%MC in about 3 months for free - using naturally accelerated air flow in our pre-drying chambers. To get the wood down to our target of 6%MC for interior use in Wisconsin, heat is required. Our Solar Cycle Kiln heats the lumber for 5-8 hours during the day, then the wood equalizes until the sun shines again. There is never a big difference between the MC of the surface and the center of the board. The wood is naturally conditioned every night - there is no need to steam the wood at the end of the cycle. It takes about 2 - 3 weeks to dry the wood from 12% to 6%MC in the kiln chamber depending on the temperature and amount of sunshine. A little extra time in the drying process pays off big time for me!
Daily conditioning with natural humidity makes the Solar Cycle Kiln very simple to build and operate. One inexpensive thermostat and one relay operate the fans automatically. There is no need for expensive stainless steel, aluminum, and other corrosion resistant materials. I can go on vacation with my sweetie for two weeks in the Caribbean - leaving my kilns alone to dry my lumber while we tan on the beach! Our kilns are fool proof, perfect for a small business.
Secret To Success - Use Free Energy to Dry Your Wood
A Solar Cycle Kiln can be built to any size needed. Our 40 foot by 20 foot kiln dry about 3,000 bf per batch. The 108 foot by 30 foot Super Cycle Kiln can dry 250,000 board feet per year in S Wisconsin. This kiln normally operates at 85 degree F over the outside air temperature, but you can reach 130 degrees F or 160 degrees F - by restricting the fresh air intake, even during winter months. My three Solar Cycle Kilns collect 1,500,000 BTUs each sunny day - for FREE!
Each kiln has three or four insulated rooms. At any one time, most rooms are open on the ends and used as pre-drying chambers. One room at a time is closed off with two insulated doors and is the kiln chamber - receiving all the heat from the solar collectors, as the lumber is dried from 12% to 6%MC. When the batch of wood has dried, the two doors slide on a track to close off a different room, changing that pre-drying chamber into the kiln chamber without moving the stacks of wood. The dry lumber is removed and the now open chamber is refilled with green lumber from the sawmill.
A key feature of the Solar Cycle Kiln is that the lumber chamber is separated from the solar collector panels. When the sun goes down and the fans shut off, one-way air valves close off the well-insulated kiln chamber, keeping all the accumulated heat at work in the lumber piles. Our 40 foot kilns use two 1/3hp fans to circulate the hot air when the sun shines. Our first Solar Cycle Kiln built in 1988 uses about once cent of electric energy to dry one board foot of lumber. Today with better insulation, air-tight construction, and one-way air-actuated valves, the electric cost has been reduced by 80-90%.
Secret To Success - Store your dried wood carefully
The kiln dried lumber is stored in a humidity-controlled room in our remodeled dairy barn. We keep our flooring and lumber right at 6% MC, another very important key to our sales success. We know that our flooring is at the proper MC and our lumber customers know our wood is dry and ready to work at any time.