Why Do Fireplaces Pop, Crackle, and Hiss?


Few things are more relaxing than having a cozy evening bundled up next to your fireplace at home. But sometimes, firewood makes noises that can be bothersome to others. Do you ever wonder why that happens and if there is a way to prevent it?

Fireplaces pop, crackle, and hiss when the wood is too wet. As a rule of thumb, you should only burn seasoned wood, as it combusts faster, makes less noise, and does not leave as much soot behind.

Burning is a very interesting process, as it can completely change the properties of anything that fire touches. Further in this article, I’ll take a look at how combustion can make firewood pop, crackle, and hiss and how to have fewer of these noises in our fireplaces.

Too Much Moisture Makes Firewood Pop, Crackle, and Hiss

If your firewood makes any popping, crackling, or hissing sounds, it means that your firewood is not dry enough. When water trapped in the wood heats up, it slowly evaporates, creating smoke–and the telltale hissing sound.

The popping and crackling sounds are caused by the same evaporation process that results in the hissing sound. When wood burns, the moisture inside it evaporates into steam. When steam gets trapped inside the tiny pockets inside the wood, it puts a lot of pressure on these “pockets,” eventually causing them to pop or explode, creating popping or crackling sounds. 

It’s completely natural for your fireplace to make these sounds. In fact, they can make the fireplace feel more relaxing to some extent. But if there’s too much moisture in the wood, the louder the sounds will be and the longer they will take to dissipate.

How Do You Stop Wood from Popping?

To stop wood from popping, you’ll want to burn wood that is dry. Drier wood will burn quieter, and you’ll have a better chance of having fireplace-ready wood if they’re stored properly and stacked long enough. 

It’s hard to tell if your firewood is dry enough just by looking at them. While time is not an accurate gauge as to the dryness of the firewood, stacking firewood for at least a year before use can allow more moisture to evaporate.

Stack Wood in a Dry Place

Proper storage or stacking of firewood is also crucial. When firewood is left on the ground, moisture from the soil can seep into the wood, making its moisture content even higher. Also, leaving wood this way will dry them too slowly.

You don’t have to be very particular about where to store your firewood. It simply has to be a dry area that is not exposed to the elements, particularly rain. Burning firewood that’s wet will create too much smoke and leave lots of soot.

How you stack your firewood is also important. Stacking them too high (or putting too many pieces on top of each other) will not allow the pieces that are too deep in the pile to lose moisture as quickly as they should. 

Season Firewood Properly

“Seasoning” is simply the process of allowing wood to dry sufficiently so that it can be effectively used as firewood. To do this, logs have to be cut to the same length, split in half, and stacked loosely so that air can pass through the pieces and allow faster evaporation. Typically, the longer the wood sits out to dry, the more seasoned it will be. 

How To Know if Your Firewood Is Dry Enough

To generate more heat, less soot, and less noise, it’s advisable to use firewood with a moisture content of not more than 20%. It can be hard to determine if wood has sufficiently dried from appearance alone, but the following signs can help:

  • Cracks on the surface. Dry wood tends to crack, as moisture loss will make it more and more brittle over time. 
  • Lighter in weight. Try to lift the wood to see if it’s lighter than when you put it in storage. Loss of moisture will also reduce the weight of wood.
  • Sounds hollow when dropped. If you drop your firewood and it gives off a cracking, hollow sound, as compared to a full, weighty thud when dropped, it can be a sign that it’s dry enough.

If you want to be more accurate, though, you can use a moisture meter such as this Giant Viking digital moisture meter (available on Amazon.com) that can be used not only on wood for paper, brick, and others.

Conclusion

The popping, hissing, and crackling sounds from our fireplaces are caused by firewood that has not been seasoned enough. While some crackling is natural, too much of it can be bothersome. 

To keep from having a fireplace that’s too noisy or a fire hazard, make sure to only use firewood with a moisture content of 20% or less.

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