Expert: Randy Brooks - 6/5/2009

Question
QUESTION: Here goes.I am rfustrated and almost out of options. I have done just about everything to stop the creosote smell from my fireplace. Let me back up a bit. about 8 years ago I purchased a wood burning insert. The installer was not able to get a S/S liner in so he installed it with a S/S flex liner about 3.5 ft long.  Also threw out the damper. (big mistake).After the first few years of burning I started to get the creosote smell. I have swept the chimney numerous times with no help. I have stuck bags filled with insulation up the flue with no help.  Then I installed a top damper. No help even with the damper closed and bag fill with insulation shoved up chimney flue. I even put a piece of sheet metal over the damper frame and sealed it with no help. On a rainy day or a very warm day the smell returns. I just recently spent $425 for a rope cleaning. I finally thought that was it but the next day the smell was back. Is it possible that the smell is comming from the fire brick in the chimney or from the mortar just below the flue ? I have not cleaned either of those. By the way the cimney is exposed on three sides. Maybe I should apply some water proofing? Any sugestions? What about airtight glass doors? Please help. I'm desperate.

ANSWER: Michael,

I would recommend that you invest in an NFPA-211 inspection of your system. Feel free to use the links at the bottom of my home page to find an inspector in your are that performs these inspections. The wood-stove insert should have a listed liner system, wrapped in insulation that extends from the insert to the top of the masonry chimney system. The oversized masonry flue working with the insert that presumably has a six inch round outlet is a creosote factory. If you sweeping service provider has not removed the insert and removed the creosote from the shelf area, you may be smelling that. You could have a stacking effect and your chimney system is acting as an air entry duct rather that exiting. Hope this helps and good luck with the inspector.

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QUESTION: Randy,
The insert has since been removed. You were correct when you suggested that the sweep service did not clean the shelf but I thought of that right after he was done and cleaned it myself. Is it possible that the creosote odor has permeated the fire shelf and the surrounding mortar? If so would you suggest that I put fresh mortar on the fire shelf and the area just below the flue? Also you mentioned a stacking effect. Could that be possible if I have a lock top damper? Thanks in advance for any other suggestions.

Mike

ANSWER: Mike,

It's possible that your lock top damper is not an air tight fit. Another possibility would be a breach in the system like a cracked flue liner and or cracks in the brick exterior. The stack effect would be a chimney termination that is shorter than than area of the house exhausting air. Usually this comes from a chimney on a single story wing of a two story house. None the less, your chimney want to act as a conduit for make up air rather than naturally drafting. I would invest in that inspection first and foremost. The surface area of the entire system will carry the odor you are smelling, so covering the shelf area with new mortar wont help much. Good luck.


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QUESTION: Randy,
Thanks once again for your input. I also thought about the liner being breached at some point but it has been inspected visually. That inspection that you refer to (NFPA-211), what does that entail? If there was a breach in a mortar joint is there anyway to repair that? I would think the the entire chimney would have to be torn down to change the liner. Is that a correct assumption? Or can the liner be changed without tearing all the cement block off?
Once again thanks in advance.

Mike

Answer
Mike,

Liners can be replaced without tearing down the chimney. The visual inspection you refer to limits the knowledge to what can be seen with the naked eye. The NFPA-211 level II inspection requires the use of an internal camera system to get a close up look at the flues integrity from top to bottom. Refer again to my web site and put your cursor on the certifications area, a drop down box will appear and click on inspections. Lots of info there. Good luck.