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Dried Firewood

Why moisture content is so important

 

The whole idea behind kiln dried firewood is to have a wood fuel that burns well and consistently. Water in the wood just naturally acts to slow down the fire. The furniture and lumber industry has been using the process of kiln drying wood to prevent drying and shrinkage over time causing warping and cracking that causes problems with the furniture or building made with wood material that is not dry. Exposed to the air the wood dries out it is just inevitable. So over time, the industry had to work on a solution.

The same technology used to dry lumber is what is applied to creating dried firewood. It is just more of a niche specialty product that many are not familiar with or at least not seen one. It is just a very, very large oven that heats the wood and circulates air around the wood to pull the water out of the wood. It is not run at 350 degrees like you would bake a cake but the hardwood is in metal bins and held at high temperatures to suck the moisture out of the wood as efficiently as possible.

The focus on Moisture

firewood kiln smallWhen the interest is on having a warm fire for its ambiance or taking the edge off a cold winter night enjoying a great fire is a primal instinct. As anyone knows who watches Chicago Fire when all the people are out of the building and they go to put out the fire, water is sprayed on the fire to put out the fire. Firemen use the opposite concept from how to build a good fire in a fireplace.

To build a good fire the wood should be stacked for good air flow, be dry and have consistent heat close to the wood fuel for the wood to maintain its self and keep burning. Firemen work to starve the fire of oxygen cool the area and remove fuel from the fire. The Huge amounts of steam are created and the burning area is cooled. The fire goes out.

The science of water on a wood fire

Adding water to the fire takes energy from the fire. The same as a pot of water takes time to boil by adding energy the water added to a fire takes away energy from the fire. It is taking the heat and causing the water to evaporate cooling the fire.

The water cools the fire and starts to coat the wood with water. This coating of water deprives the fire of oxygen that is critical for a fire to burn. The water is sprayed in a fine mist to help disperse it over the fuel to coat the area as best as possible. The effort is to soak the fuel not just heat the water. Less oxygen to the wood means less available to burn the wood. Calculation for heating water is the mass of water times the heat capacity of water to evaporate it. A BTU is the amount of water to heat one pound of water on degree. So the more water added to a fire the more the mass of water puts out the fire.

The same theory applies to water in firewood. It is talked about as moisture content in wood. It naturally fights against the wood to burn since the water has to evaporate first before it can burn. So the water is just like a fireman trying to put out the fire.

How much water can be in firewood?

wood with water in itIt all depends but it can be as high as over 120% in some woods that are not real dense. As an example in freshly cut Sugar Maple (Acer Saccharum) is about 60 % no one disagrees that a dried hardwood is great for burning but all the terms about green, seasoned and kiln dried all revolve around getting the water out. A cord of maple green can weigh 4684 lbs. then when at 20% the weight is 3,680 lbs. so about 1,000 pounds of water have been removed or to put it in the context another context of gallons it would be taking out 143 gallons.

The benefit of Dried Wood

Kiln drying quality native hardwoods provides consistency for the customer. Avoiding the need to dry the wood and a quality wood input is what creates the quality. High density wood with minimal moisture provides an easy to light fire and a fire that has a good duration. An example to put all this in terms of the user is as follows. A company sold a wood stove and the customer could not get a decent stack temperature. The stack temperature is a measure of heat the stove can provide. He was getting 250 degrees and felt it was the stoves fault. Visiting the customer, the person who sold the stove took our kiln dried wood started burning that and the stack temperature went to and stayed at 520 degrees for hours controllably. If you enjoy a nice wood fire buy some amount of our kiln dried wood and see for yourself if our kiln dried wood and stacking service is worth it.