I recently purchased a home that had a custom gas &/or wood fireplace professionaly installed in the mid to late '80's. It has a masonry fire box, masonry hearth and ash pit, as well as a stone veneer exterior with a custom steel hood and damper. All this is in excellent condition and barely used. My issue/question is concerning the chimney portion. From what I can tell from the roof-the steel pipe chimney looks to be 10" single wall pipe. I'm concerned as to the safety of this? Was this a common install back in the 1980's? Should it be double wall? Would they have converted to single wall once outside the house or would this mean I have single wall all the way down? Is there a simple way to find out? This is in a ranch home, so the entire height of the chimney is only about 8-10 feet.
The previous owner had the firebox set up with a rotisserie and gas start for cooking over charcoal and I have converted it to a vented gas log set up. I'm concerned with the gas log setup that I may be producing too much heat for the exhaust stack if it is truly single wall. It just amazes me that they would have used single wall pipe on this? I spoke to a local fireplace dealer and they said this was common at that time?
Also-I think the 10" pipe may be undersized for the fire box size. The opening of the fire box is 24" x 48" (and 24" deep) with a 36" 96,000btu gas log set up. I've only put about 4 hours of use on the new log system, but I'm getting some minor draft issues. Should I consider reducing the size of the fire box opening to improve draft?
You have some great questions and should be commended for asking rather than putting yourself and family potentially at risk. the 10" inch single wall sounds odd to me as well and I'm certain that is an issue. My recommendation is for an NFPA-211 level II inspection to be performed to make certain. Please use the links at my home page at www.brooks-hearth.com to find an inspector offering this service in your area. best of luck to you and your family.