Our new home uses a Zehnder ERV (Energy Recovering Ventilation) system to provide continuous fresh air to the very tightly sealed building. Today, I installed the exterior intake and exhaust vents which look and act like nostrils. I then powered up the system for the first time. Everything worked as expected and the system self-test confirmed that the unit can deliver its maximum specified 600 cfm of airflow. At this rate, all the air in the house could be replaced with fresh air once every hour. The recommended rate of exchange is once every three hours so we will operate the system at 200 cfm.