When lighting up a fire in your fireplace this winter, take a moment to think about the wood you’re using. Seasoned wood is the best to work with, as it will light quickly and burn longer than the non-seasoned variety. Here are some tips on ensuring you use only seasoned wood, how to determine if it is indeed seasoned, and the risks of burning wet wood.
Moisture Content
It’s important that the moisture content is 20% or less. For example, the wood you find at home improvement stores, gas stations, and grocery stores is guaranteed to have a moisture content of 20% or less. If you are planning to become a long term wood burner buying guaranteed low moisture wood can get expensive. If you’re buying your wood elsewhere and aren’t sure, you can purchase a moisture meter at any home improvement store or online. Just be sure to split the wood before you stick the moisture meter prongs into the wood for testing. Pretty and heavy wood is not properly seasoned. The “I’ll get a splinter just looking at it” kind of wood is what you are after. Dull or gray and lightweight with large cracks on the cut ends is how dry wood looks.
Problems with Burning Wet Wood
Many people have a pile of wood sitting outside on the ground that they would like to burn in their fireplace. Problem is, that wood is unseasoned by soaking up moisture from being out in the elements. Seasoned wood simply refers to wood that has been properly dried. Unseasoned firewood can have up to 50% or more of moisture, which is never a good thing when it comes to your fireplace. Wet wood is hard to light, creates a stronger smoke smell inside your home, causes smoking back issues, and does not produce as much heat. Unseasoned wood results in an incomplete combustion, creating more smoke traveling up the flue. This increases the “residence time,” which refers to the time from when the smoke leaves the firebox to the time that it exits the flue. When you increase the residence time, the flue is not hot enough to establish a sufficiently strong draft to release the smoke fast enough. The flue walls will be cool and the smoke will condense on the sides of the chimney walls, creating what’s known as creosote.
Creosote is a natural by product of burning wood. It is highly combustible and acidic which can cause the deterioration of mortar joints, dampers, and caps. The presence of too much creosote can increase your chances of experiencing a chimney fire. A professional chimney sweep can tell from the type of creosote buildup if you have been burning seasoned dry wood.
The three types of creosote:
- 1st Degree creosote is a powdery type creosote normally easy to remove by sweeping the chimney. This is the type of creosote that is associated with burning seasoned wood.
- 2nd Degree creosote resembles black corn flakes and at times is harder to remove. Typically associated with wood having moisture content a little too high.
- 3rd Degree creosote is a black glassy tar like substance that is the most flammable of all. Also, the most difficult to remove which usually results in the use of chains and chemical treatments. This is usually the result of burning wood with a very high moisture content and slow moving smoke.
There’s a common misconception out there about pine creating a lot of creosote. The truth is, if you burn seasoned pine that isn’t sappy or so-called “fat wood,” it will actually create less creosote than hardwoods that have seasoned in the same amount of time. This lessens the residence time and in turn establishes hotter flue temperatures allowing the smoke to exit the flue system faster. However, pine does burn hotter and faster therefore most choose to burn a hardwood for a longer burn time.
How to Season Firewood
We suggest not to burn wood any larger in circumference than a mayonnaise jar. For example, oak on average takes an inch per year to season properly, so for a three-foot diameter log, it may take 20+ years for an unsplit log to season. You have the best chances for successful seasoning if you cut and split the wood, then stack it up off the ground, allow space between your rows for adequate air flow, while keeping it covered at least a year in advance. If you are or may become an avid wood burner a wood shed is a wise investment.
Still have questions about seasoned firewood? Give us a call and we’d be happy to offer more information, book an appointment, or give you an estimate.