Q&A Gas Fireplace vs Wood Burning Fireplace

QandA Posted By QandA, Nov 24, 2007 at 5:26 AM

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  1. QandA

    New Member 2.
    Staff Member

    Nov 27, 2012

    Dear Sir: I live in a two story house which was built in 1926. The fireplace chimney goes up through the center of the house. My wife and I have lived in this house since 1969 and have not made any changes to the fireplace, so we are fairly certain that the fireplace has not been changed in 74 yrs. We have burned wood in the fireplace occasionally, but not on a regular basis. The mortar in the back wall of the fire box is deteriorating and we are having it repaired. The top of the chimney was tuck pointed several years ago and is still in good shape. The repairman has just today told us that we have a "gas fireplace"; based on the fact that there is no "box lip" and "smoke chamber" just above the flue. He indicated that we are lucky that we have not burned our house down and that we should not burn wood in this fireplace. To our knowledge there has never been a gas line to the firebox and it has never been used as a gas burning fireplace. My questions are as follows:
    1. Did fireplace designers differentiate between gas and/or wood burning fireplaces in 1926, or were they all of the same design at that time?
    2. When did fireplace designers start designing a different style chimney for burning wood? I'm sure that at one time all chimneys were straight up, like ours.
    3. On the basis of what I have been able to tell you; please give me your opinion as to whether I should be concerned about burning wood in this fireplace? Thank you.


    I've swept chimneys that were 175 years old, and ones that were made in the 1980's. They've all had different characteristics in shape, design, size, and height. Some are totally straight, and some have offsets. Fireplaces are built by masons who learned their trade from the mason that they apprenticed for. So, there could be generations of fireplace construction & designs that could be faulty prior to formal code officials. That doesn't mean yours is faulty, but the point I'm trying to make is that fireplaces will vary---there's no such thing as a standard fireplace.

    But, every fireplace I've seen has had certain standard features; damper, smoke chamber, and smoke shelf. I've not heard the term or slang "box lip" before. I'm not sure if he's referring to the overhang in the front of the fireplace, or a smoke shelf just above the damper. A smoke shelf is designed to mix cooler air with the hot gases/smoke leaving the firebox, or hearth area. Without it, you may have hotter flue temperatures. Perhaps that is what your repairman is referring to when he stated his concerns.

    I'm not aware of "gas only fireplaces" in the 1920's. I believe that the first gas logs were introduced sometime in the early 1950's. Based on your inquiry, to give a blanket answer saying that it's safe would be a disservice. There are other factors such as clearances to combustibles along the chimney as it extends through the home, tile lined or brick lined flue, condition of the entire flue (loose mortar, cracks), and most of all performance. Here's my suggestion. Contact a chimney sweep who is certified by the National Chimney Sweep Guild and ask for an inspection. Get a chimney expert. I'm sure your repairman is a fine masonry repairman, and he may be correct in his assumption. But there are other factors that should be explored as well. Armed with that information, you can make an informed, educated decision. Good luck.

    Link: Chimney Sweep Institute of America
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