We have a new Kozy Heat Carlton 46 gas fireplace. We love the look and the heat output, but the whistling noise from the roof vent is so irritating. With the slightest noise, the vent whistles. It's blowing 10-14 mph now, which is considered a "gentle breeze", and its whistling along. I would expect some noise if it were really blowing out there, but not at a gentle breeze. The installer and manufacturer have been unable to solve the problem. Any ideas? Thanks!