I have a Hayward H1501 gas heater that earlier today I fired up for the first time this season. It is ony 2 years old. It was making a whining/whistling noise and the top of the chimney part (not sure what it is called) has black soot on it. Is this what is called "sooting"? Are both of these issues related and caused by low gas flow, or is there another issue that could be causing it? Will this damage the heater, and what can I do about it. I've tried to attach a couple of pics so hopefully you can see what I am talking about. Thanks.