I have an existing space heater in an older home with a traditional flue, B vent. I want to install a a hanging furnace in my attached garage. The hanging furnace has a power vent exhaust. Can I vent both of these through the same (existing) flue? Changing the pipe(s) on the existing is not an issue if it is possible. I was wondering if the fact that the new furnace is power vented would be a consideration in executing this arrangement.