I am in the process of finishing my basement. I am having the walls and rims foamed next week. Because the foam insulation seals all cracks I am concerned about circulating fresh air. I do not have a separate hvac system for the basement, howver, I do have vents from the system that heats the main floor. It stays very comfortable during the summer, normally about 65 degrees and I plan on adding a wood stove for additional heat in the winter. Do I need to add a heat exchanger of some type? Any recommendations would be appreciated.