Seconding the large impact of an ERV, the air inside feels much fresher when it's on vs when it's unplugged. I've taken to just running the HVAC fan at all tim

Seconding the large impact of an ERV, the air inside feels much fresher when it's on vs when it's unplugged. I've taken to just running the HVAC fan at all times, regardless of whether heating/cooling is happening. This tends to even out the temperature throughout the house, as well as CO2 concentration, it keeps the air filtering through the HVAC HEPA filter, and the ERV can run continuously, so rooms rarely get above 600 ppm CO2. Unsure about the energy use impact, but the air quality difference is palpable.