Not sure if this is the correct place to post this. But on our gas boiler, if you run your finger along the back of it, its covered in a black soot-like substance. Is this a problem? I was surprised to find it there, I would have assumed it would be clean or dusty at worse.
The outflow from our boiler goes out through the side wall of the house to the outside.
The outflow from our boiler goes out through the side wall of the house to the outside.