My current setup will soon change. My oil boiler is a power vent. The contractor obviously saved some money by not installing a chimney. The house has an insert fireplace with a 12" insulated flue through 2 stories. I plan on removing the entire fireplace & flue then installing a 3 flue CMU block or brick chimney in its place (large cavity in walls). Following the install, can I reuse my powervent boiler and tie it into one of the flues?