The cost below are based on using the MiniQuick firewood kiln operating at 250F temperatures and does not include cost of purchasing, freight expenses and installing the kiln at your facility.

Drying cost for doing six cord of firewood (MiniQuick kiln).
This is based on green wood  and fresh split.

	Wood Waste	Natural Gas	LP Gas
Estimated total amount of btus needed.	16,000,000 btu
Heat source	1 cord	160 Therm	175 gallon of LP gas
Cost for heat  source	$70.00	$112.00	$2.00 per gallon
Labor hours needed	2 hours	Minimal	Minimal
Cost of labor ($12.5 per hour)	$25.00	$0	$0
Total heating cost for 6 cord of firewood	$95.00	$112.00	350.00
Electrical cost (5kw x 10 cents/kw x 36 hrs)	$18.00	$18.00	$18.00
TOTAL COST OF DRYING 5 FIREWOOD FROM GREEN	US$: 113.00	US$: 130.00	US$: 368.00
ESTIMATED COST OF DRYING A CORD FROM GREEN	US$: 18.83	US$: 21.67	US$: 61.33
		This amount will increase as gas costs increases.	This amount will increase as gas costs increases.
IT SHOULD BE MENTIONED: Kiln-direct has several customers that use gas and have reduced their gas consumption by: - Air drying first, - Drying smaller diameter pieces, - Create semi-dry firewood and managing the delivery process to prevent mold.

The drying times in this answer are strictly related to our firewood kilns unless otherwise noted.  This is important to understand as our kilns are significantly faster than other firewood kilns on the market, especially the container based units being sold.

In August 1987 the Forest service made a small study of drying oak firewood at different temperatures:
Kiln-Drying Time of Split Oak Firewood (www.fpl.fs.fed.us/documnts/fplrn/fplrn254.pdf) (PDF file 171kb)


Comparing heating methods:

Heating method	Heat surface temperature	Top temperature in chamber	HT times (160F/75min)	Drying times
Hot water (200F)	175-195F	170-180F	NA *	4-7 days **
Steam - low pressure -15 psi	240-250F	210-220F	12-24 hrs	2-4 days
Steam - high pressure - 65 psi	300-310F	270F + ***	8-16 hrs	1-2 days
Indirect fire - with air-to air heat exchanger (Quick firewood kiln)	400-1100F	270F + ***	8-16 hrs	1-2 days
Direct fire - gas only	2500-3000F flame temp	270F + ***	8-16 hrs	1-2 days
Above estimates are what we have basically seen in the market (it always is to some extend) * HT times for hot water is not possible until firewood is dry. ** We have heard that 3 days is possible in some very well designed hot water kilns. *** We do not believe it is safe to go above 270F in a firewood kiln.

The speed with which you can dry or heat treat firewood will depend on the following: the heat system output at a high temperature plus the ability of the air circulation to bring this heat to the firewood.

Note about hot water heating stoves for wood waste:
It makes perfect sense to use a hot water stove to heat the kiln and the firewood. However, the hot water coming from the stove is normally only 185F-200F, so it is impossible to get the kiln temperatures to 190F as we do with the direct gas heating system. So the kiln will normally operate at 130-140F for preheating and drying purposes with the hot water. Then the gas is switched on for the final 4-6 hours to insure the load meets the USDA HT regulation. THE MINIQUICK FIREWOOD KILN HAS CHANGED ALL THIS, IT DOES NOT NEED  GAS TO FINISH THE JOB.

We hope this has answered your question. If you need more information or have additional questions, please do not hesitate to contact us.

We all know that well seasoned firewood burns better in the fireplace and stove, plus they do produce more heat.

We need to understand that drying and heat treating are not the same thing, but they can be part of the same process.

Heat treating firewood is used for sterilizing firewood to kill insects and certain bacteria. This is quickly becoming a requirement for moving firewood over long distances to prevent the spread of certain insects, such as EAB (Emerald Ash Borer). You may disagree with these rules, but they are quickly being implemented in more and more states, either through state or federal regulations.

Drying firewood (in a kiln) is basically to speed up the seasoning process plus you will not get the graying in color that is common on well seasoned firewood.


We hope this has answered your question. If you need more information or have additional questions, please do not hesitate to contact us.

There are two different standards in effect:
- 140F for 60 minutes at the center of firewood (New USDA standard for EAB)
- 160F for 75 minutes at the center of firewood (Older USDA standard for all insects)

Please contact your local USDA to determine which standard will apply to your area.


The governing will either be:
- Local DNR (Dept of Natural Resources),
- Department agriculture of the state,
- USDA.
We have seen different compliance rules and guidelines for these different government bodies.


How Kiln-direct exceeds standard compliance rules:
All Kiln-direct firewood kilns come standard with 2 chamber temperature probes (dry and wet temp.) and 6 internal wood temperatures which exceed the USDA requirements and should offer redundancy if a sensor was installed wrong or needing to be deactivated for any reason. Our system also records all temperature readings every 2 minutes. USDA only requires a reading every 5 minutes, which means you can lose a reading and still be compliant.

We currently have our firewood kilns operating in 20 states with more on the way.

We hope this has answered your question. If you need more information or have additional questions, please do not hesitate to contact us.

It takes energy to dry firewood. When firewood is naturally seasoned then this energy is extracted from the outside air. When firewood is dried in a kiln then we have to use a fuel source to dry the wood. This fuel source can be oil, gas, wood waste, etc. On this page we will look at the average energy consumption and the cost for drying fresh split (green) firewood.

Energy cost for drying 1 cord of firewood.

	Theoretical Lab conditions	Firewood kiln conditions
Estimated weight of green firewood: (Oak=4900lbs, Maple, soft=3960lbs, Ash=4240lbs, Hackberry=4040lbs, Alder=3600lbs = average 4150 lbs/cord	4150 lbs/cord
Estimated weight of dry firewood: (Oak=3425lbs, Maple, soft=2640lbs, Ash=3180lbs, Hackberry-2940lbs, Alder=2220lbs = average 2880 lbs/cord	2880 lbs/cord
Amount of water extracted per cord of firewood to become dried.	1270 lbs/cord	1270 lbs/cord
How much energy will it take to evaporate 1 lbs of water: Starting temperature is 60F. Raising 1 lbs of water from 60F to 212F = 152btu (1btu = 1F per lbs) Evaporating 1 lbs of water at 212F = 971 btu. Theoretical energy needed to evaporate 1 lbs of water from 60F = 1123 btu First it there is a heat waste factor in any kiln. Basically you will need significantly more heat to get this done due to heat energy escaping during venting, walls, floor, and other inefficiencies. The rule of thumb in lumber drying is 35-60% waste factor. this means it will cost between 1700 to 2800 btu to evaporate 1 lbs of water in a kiln.
How much energy does it take evaporate 1175 lbs of water from firewood: Theoretical: 1270 lbs of water x 1123 btu/lbs = 1.4 million btu (not possible) LOW Estimate: 1270 lbs of water x 1700 btu / lbs = 2.0 million btu HIGH Estimate: 1270 lbs of water x 2800 btu / lbs = 3.3 million btu	1.4 million btu	between: 2.2 million btu and 3.6 million btu
How much energy does it take to raise 1 cord of firewood from 60F to about 212F: Average weight of firewood dry (with 20% water) = 2880 btu Temperature increase is (212F - 60F) = 152F increase Approximately 1 btu / lbs / 1F increase. Total energy needed to raise wood temperature  (2880 lbs x 152 btu/lbs) = 437760 btu.	approx. 440,000 btu.	approx. 600,000 btu.
Total energy consumption to dry 1 cord of firewood: THEORETICAL: (1,400,000 + 440,000) btu = 1.8 million btu LOW estimate: (2,200,000 + 440,000) btu = 2.6 million btu HIGH estimate: (3,600,000 + 440,000) btu = 4.0 million btu Kiln-direct MiniQuick Firewood kiln will be very close to the LOW estimate as that kiln design relies on "boiling" the water out of the wood and letting the "steam" escape instead of venting.
TOTAL COST IN ENERGY TO DRY ONE CORD OF WOOD IN THE MINIQUICK FIREWOOD KILN	1.8 million btu.	2.8 million btu. to 4.2 million btu
Estimated cost of energy with wood waste: 1 cord of firewood is normally between 15-20 million btu (cost per cord = $0-$100)	~10% of a cord up to $13	16%-24% of a cord $16 to $24
Estimated cost of energy using LPgas Each gallon of LP gas = 91000 btu / gl LPgas Current gas costs: $2 per gallon THEORETICAL: 1800000 / 91000 btu/gl = about 20 gallons LOW estimate: 2800000 / 91000 btu/gl = about 31 gallons HIGH estimate: 4200000 / 91000 btu/gl = about 46 gallons	$36	$56 - $84
Estimated cost of energy using Natural gas 1 cubic foot of Natural gas = 1000 btu (100 cu.ft = 10 Therm) Current average cost for 1 Therm of natural gas: $0.7 per Therm THEORETICAL: 1800000 / 100000 btu/Therm = about 18 Therm LOW estimate: 2800000 / 100000 btu/Therm = about 26 Therm HIGH estimate: 4000000 / 100000 btu/Therm = about 40 Therm	$12.60	$19.60 - $28.00