What does a sweeper look for when inspecting you flu- pipe anything that I couldn't do myself with a thourough brushing? Also, when I'm gunning up the stove from cold tp 6- 700* to clean the pipes, I hear a ting ting'ing at the warm up. Is this the metal expanding or any creosote depostes getting fried? Also- I burned a C.S.L. loge recently, how good are they really...............