How To

How to Get the BTU Value of Firewood

By Kat Yares, eHow Member Rating

Rate: (6 Ratings)

BTU, or the British Thermal Unit, measures the heat value of an energy source. When it is used to measure the heat value of wood, many factors come into play. Taken by the pound, all woods produce the same amount of heat. Firewood should be seasoned or dried for at least a year to increase the BTU value it produces.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

Knowledge of wood species to burn
Computer
Internet connection

Step 1

Determine what species of wood you have in your firewood stack. A number of places online list the BTU values of different species of wood. I’ve listed a few below. An Internet search will reveal more.
Step 2

Choose dense woods for higher BTU values of each individual piece. Dense woods include oak, hickory and birch.
Step 3

Burning green wood will produce fewer BTUs than seasoned wood.
Step 4

Pick a softer wood for a quick, hot fire. Soft woods include basswood, some maples, poplar and aspen. All evergreens are considered soft woods.

Tips & Warnings

A BTU is determined by how much energy it takes to raise the temperature of one pound of water one degree.
The amount of BTUs in a given wood is based on factors such as moisture, density, ash and resin.
Properly seasoned hardwood firewood should produce approximately 7700 BTUs per pound.
Green firewood’s BTUs drop to around 5500 per pound.
For maximum BTU’s, firewood should be cut in the winter when the sap of the trees is down. It should then be allowed to cure for at least a year before burning.
To speed drying time, firewood should be cut to length, split if necessary and stacked to season.
Softwoods such as pine, while producing a quick, hot fire, also build creosote in the chimney and can lead to a chimney fire.

Resources

Comments

CCrock said

Flag This Comment

on 1/3/2008 thank you for this info. We are always burning wood in our fireplace and some of the new wood we've been using wasn't producing much heat. Thanks for explaining about the BTU differences.