Expert: James Ball - 5/31/2009

Question
I'm renting a 1920 house with a masonry fireplace. I was having a problem with very strong smoke odor after a new central heating system was installed with a single air return vent located 10 feet from the fireplace. The property manager hired a chimney sweep, who cleaned the chimney with a "creosote foam degreaser", and caulked the deteriorating mortar between the bricks in the firebox with a "silicone glue," after which he painted the whole firebox shiny black with spray paint. I asked the sweep not to use chemicals in my fireplace because I was concerned about them off-gassing toxic fumes into my living space, but my objections were ignored with assurances that the chemicals were harmless. There was a terrible smell from the chemicals that has taken two days to start to dissipate even with a fan continuously running. I tried to research this online, and didn't find anything that would indicate high heat silicone is appropriate for firebox repair -- refractory cement is what seems to be recommended -- and am doubly worried after reading an answer to another question here recommending against the use of chemicals in chimney cleaning because they can "cause lung damage." This is particularly of concern to me because the smell problem only occurred when the furnace was running, leading me to conclude that negative air pressure caused by the huge air return vent drawing air in through the bent and leaky old iron damper was what was causing the problem. I had requested that an air tight top sealing chimney cap be installed to address the problem, but it was declined because of the cost. So now, in addition to smoke smell from future fires, I seem to have the added concern of VOC's from the fireplace being drawn in and circulating in the air I breathe. I have a small pet parrot who is even more vulnerable to commonly used toxic chemicals in household products, fumes from which can kill a bird. I'm wondering what chemicals are contained in the paint, silicone, and creosote degreaser that were used (I don't know the types or brands), how they react under the high heat generated in a firebox, and what my options are now that they have already been applied? Do I have cause for worry? Where can I turn for more information? Thank you for your help.

Answer
Hello Lena, My first idea is to burn off the chemicals (I do not know what "creosote foam degreaser" was used, no "Silicone glue " should not  be used in a fireplace. and any paint will burn off with the next fire. But most of all you still have the negative pressure problem.
with out seeing this set up I have a few ideas, 1) burn a controlled fire in the fireplace and smoke chamber (get rid of chemicals and cure the paint) 2) remove the silicone and use fireplace cement (home depot/loews) 3) install the top mount damper cap, 4) move the AC return to another room. 5) you may still need to open a window (for this solution) and to use this fireplace in the future.

I would have a local Certified Chimney Sweep (www.csia.org, there you can look up by zip code to find one near you) take a first hand look at what you have they should be able to help.
good luck and keep me posted
James