Fire. Something about fire touches our brainstems…both good and bad! Uncontrolled fire is terrifying and deadly to be sure. But the controlled burning of wood at a campfire or in a fireplace in your home almost can’t be beat, to my mind! For that very reason, a fairly common amenity to houses nowadays is the gas log fireplace insert.
When not installed properly, these logs will generate soot. These soot particles can leave the fireplace and meander. All. Over. Your. House. Literally, if enough soot gets into the HVAC system, you can have soot in every room. If the logs soot badly, you will notice right away and correct the problem. It’s when the logs produce lesser amounts of soot that it will build up so slowly as to not be noticeable. That is, until you adjust a picture frame and notice how dingy the wall has become.
It can cost tens of thousands of dollars to clean soot from a home. Soot removal is a specialized restoration service that a typical homeowner cannot provide for themselves. Where there is soot, there is also carbon monoxide which can cause a host of physical ailments, as well. Prolonged exposure to soot can unleash a host of breathing problems, including asthma, bronchitis, and respiratory infections.
Figure 1: Properly aligned logs in a gas burning fireplace allow for a much better ambiance.
Why does this happen? Remember that combustion is a chemical reaction at its roots. The clean, or complete, combustion you want in a furnace or stove results in that quintessential ‘blue’ flame. And in those applications, that is exactly the desired result; maximum efficiency and heat for heat transfer. However, if the fuel-to-air ratio is modified, you can bring some yellow to the party and have a gas flame appear more like the flames generated by a wood fire. Still, the yellow Bunsen burner doesn’t draw you to sit down to bask in its output, does it?
Figure 2. Different fuel-to-air ratios dictate flame color in a decidedly unromantic Bunsen burner
Hence the gas log fireplace insert. At the heart of it, a typical gas log fireplace insert is a burner that has the proper fuel-to-air ratio for either natural gas or propane to produce the yellow flame similar to a wood fire. They also have ceramic ‘logs’ that are placed around the burner to further mimic the look of said wood fire.
The proper placement of the faux logs is critical to the safe operation of the fireplace, however. From the front, the logs give the appearance of a stack of wood. If you inspect the set from the top, however, the area around and above the burners is free from objects. If the logs are not properly placed or get knocked out of place and get in the way of the flame from the burner, then impingement occurs. The flame impinging on the ceramic log will cause soot to form.
Figure 3: Soot on a ceramic log that was placed improperly. This condition can cause soot to spread throughout the house.
Therefore, when installing a gas fireplace insert follow the log placement instructions carefully! If there is no glass in between the logs and whatever room they are in, it’s also not a bad idea to check the log placement when doing annual maintenance on your fireplace insert.
Jennifer Morningstar, PE, CFEI, has 19 years of industrial experience. Her areas of emphasis include chemical release & exposure, OSHA process safety management, industrial accident investigation, fires & explosions, and scope of damage/cost to repair analyses. She spent 16 years working at a polyethylene terephthalate (PET) manufacturer. She is an OSHA-trained Process Hazard Analysis study leader and completed Root Cause Failure Analysis training to become an Incident Investigator. Jennifer authored procedures for lockout/tagout and confined space entry. She has experience as an energy management consultant in a variety of industries including mineral extraction, pulp & paper, animal harvesting & packaging (including rendering) and grain milling. Jennifer holds a Bachelor of Science Degree in Chemical Engineering from Virginia Polytechnic Institute and State University as well as a Masters of Business Administration from the University of South Carolina.