Couple thoughts here: Back in the 70’s some stoves were manufactured and listed to be able to reduce the flue collar from 8”
to 6”. Todays code prohibits flue collar reduction, unless your appliance has been tested and listed for it to do so. If your used stove is unlisted as were most stoves manufactured prior to 1979. It can not legally be installed. To find out whether is listed there will be a manufactures tag usually located on the back, Listing the UL listing. EVen Modern box stoves manufactured by Volzang are stated not UL approved. They cannot be installed in a residence. They can be installed in a shed, but the shed cannot be attached to the occupied dwelling. Many older stoves were not enviormently friendly. They are smoke belching poluting beast, no where near as effecient as today’s EPA approved stoves. Many never had the loading doors gasketed and easilly overfired. Without gasketing, there was no way to be able to fully control the air feed. It simply bi passed the controls and filtered around less than air tight doors.
We have already recorded one such fire, where the older stove got going to Cherry red touching off the Mantel and near by ensuing combustiables. So far this year, I have had to condemn 4 Un listed stoves and demanded their removals. I would check with your local inspection Dept., to see if they allow the installation of unlisted stoves, or whether they would allow flue reductions. It’s a lot cheaper now, know ahead of time, than to see that comdemned stove sitting out by the curbside
