Our 1893 house was thoroughly renovated circa 2006 before we bought it. There is a centrally placed open fireplace with a masonry chimney with one 8" metal liner which runs up to the cap. A second metal pipe runs parallel from the gas boiler and water heater in the basement. What can I assume about this install regarding code for that time, specifically whether the liner is insulated or not? I've been using a smallish insert with a 6" to 8" adapter plate for the past few years but have been planning to upsize to freestanding and want to be safe on the chimney side of things.