Hello, I am in the process of installing a US Stove, model 1500 in my workshop. It is a new, but pre-EPA, wood and coal burning furnace. In anticipation of this install I purchased 6" Duravent double wall stove pipe. This is to connect to the flue at the rear of the furnace using their T-pipe. It will run vertically to where it meets a Duravent triple wall stainless chimney pipe and then exit the roof. It is a straight run with no obstacles. US Stove suggests a barometric damper in the vertical run just above the stove. Duravent sells a single wall T-pipe with a Field Controls unit installed, but not a double wall T-pipe with same. First question; I already have a Field Control 6-R-C barometric damper. It will not slide over the inner sleeve of the double wall T. If I use the included collar it would slide into the T, thus possibly obstructing vent flow. Can I get by with using Duravent's, double wall, hand operated damper connector mounted to the rear of the stove? Because I am using double walled pipe which, seemingly, doesn't allow the installation of a barometric damper, do I even need a barometric damper with that pipe? Second question is; With a barometric damper installed US Stove states the need to drill a hole in the pipe below the damper and insert a manometer to get a reading and to adjust the correct air flow. Do I really need to spend $100.00 plus to acquire a meter to do this? Is there something a little more sanely priced that will do the job? I thank anyone for your response.