woodfired hot air firewood kiln

allagashwoods · January 31, 2011, 06:57:13 PM

Hi,
First time post,I want to build a forced air wood fired furnace to dry firewood. I have a 40 ft. insulated container and a free supply of wood to burn. I have not seen one but I can not see why it would not. The price to do this compared to buying an up and running kiln is a fraction of the cost. Any feed back or suggestions would be very helpful.

Thank You,allagashwoods

Den Socling · February 12, 2011, 09:35:06 AM

Since you only want to dry firewood, you aren't looking for even air flow so why not simply stack and duct the air to the stack? This could supply firewood for you but for a commercial operation, you need documented temperature. At least you do in PA.

BTW Welcome to the forum.

Buck · February 12, 2011, 09:41:14 AM

Sounds to me like a product that is marketed by Mountain Firewood Kilns in NH. Look em up. A look around there might show you what you're getting into.

John Mc · February 22, 2011, 11:26:18 AM

I don't know much about kilns, but I know you need to choose your insulation to stand up to the heat you're going to generate. Some of the foam board used in housing will not take the heat.

albirk · February 23, 2011, 05:07:33 AM

how hot and how long do you need to run the kiln to kill all the bug?

allagashwoods · February 23, 2011, 05:12:41 PM

Hi, to kill the bugs or to be certified heat treated you need the temp 170 for 4 hours and you need probes in the wood linked to a software program to record it and prove the results. I think eventually any large firewood operation will be forced to do this.This won't be an issue for local guys selling small amounts. To kiln dry,which is different from heat treated you would have to dry the wood for 3-4 days at a temp of 180-200 depending on the type and age of the wood.

Len

John Mc · February 23, 2011, 06:27:39 PM

I thought I had just seen some updated information that lowered the required temperature a bit. I didn't pay much attention, since I'm not in the business. Did anyone else see this? 140 F sticks in my mind, but I may be all wet on this.

allagashwoods · February 23, 2011, 07:53:28 PM

John, you are correct. it's 140 degrees,I am having kiln overload trying to figure out my move on building a kiln. The wood fired hot air seems to be the way to go but I am not having much luck finding anyone with experience with one. Kind of makes nervous about going this route.
Len

kilndirect · April 02, 2011, 10:20:18 PM

Full disclosure: We manufacturer firewood kiln and they are hot air heated.

Here are some helpful links information about drying firewood:

Energy needed to dry firewood: www.kiln-direct.com/firewoodenergy

Study on drying oak firewood at different temperatures: www.fpl.fs.fed.us/documnts/fplrn/fplrn254.pdf

Comparing heating systems and drying times based on our observations in the field: www.kiln-direct.com/faq-firewood-dryhttime

USDA have reduced the threshold for heat treating to 140F. It is not for certain that every state follows this lead. Historically 160F (70C) has been temperature for heat treating wood products, then the ISPM-15 standard for heat treating export pallets and packaging was set to 133F for 30 minutes. Time will only tell where the final treatment threshold is.

I hope above information is useful.

Niels