You guys got slow down I'm an old fart I cant type that fast lol
First thing I did when I figured it was the water tank,[less than 5 min] was put my cig up there and that's all it took.
Thats when I called the installer to give him the good and bad news.
I did indeed remove the sealed sections, and retested to make sure.
And that was only a 24cu.in. leak , but that's what is making the difference between "back drafting" and not!!!!!!!
He knew that I'm not an idiot, and that the problem was only created by that single incident, and that "undoing" it , [and I even opened it up some more] would "alleviate" the issue. As i said I rechecked it several time's and it's not back drafting any more.