I think that I have a bunch of heat going up my chimney so I bought a Drwyer Monometer to check the draft. I have a 6" flue pipe with a manual damper about 12" above the wood stove. Do I check when the stove is hot or cold? Do I drill a hole in the pipe for the tube? Is it ok to drill a hole in the flue pipe without smoke coming out of it? How far up the pipe do I drill the hole? How do I use the tube in a hot pipe with melting the tube?