You may find this story hard to believe! We had a customer recently that had just turned on her heating unit for the first time earlier this season. When we arrived to clean, we found a black soot on much of her furniture, ceiling, lamp shades, and window sills. She had no idea what had happened or when. After calling a specialist to check her duct system and heating unit, it was found that it was from burning her Yankee candles too long and from not cutting off the mushroom top wicks! She was on a daily basis lighting her candles without cutting the wicks, starting around 3pm and did not put them out until she would get ready for bed. After time, it caused a build up in her heating system and when she turned on the heat for the first time of the season, it all blew out!
Leason learned....cut your wicks before lighting your candles, and they should not burn for no longer than 2 to 3 hours.