I have a harman Accentra insert, and I was considering cleaning the chimney insert myself this year. The mating point where the stove pushes into the flue area is a small square opening. can I get a 4" brush through that hole? Is this the best way to do it? I was just going to push the brush up the 4" liner until it stops, then pull it back down, while holding a vac near the opening that i am pushing the brush through. I live in a pretty tight neighborhood, so blowing the soot out the top is not an option!