Is the ERV fan motor supposed to run all the time?

Yes, an ERV (Energy Recovery Ventilation) motor is designed to operate continuously, but it may not necessarily run at the same speed all the time. Most ERV systems are equipped with variable speed motors that can adjust their speed based on the system's ventilation requirements.

During normal operation, an ERV system typically runs on a low-speed setting to provide constant, balanced ventilation while minimizing energy consumption. The low-speed setting also helps to reduce noise levels and maintain a comfortable indoor environment.

However, the ERV motor may increase its speed when the system detects a higher demand for ventilation, such as during peak occupancy or when there is high humidity or pollutants in the air. This allows the system to maintain a healthy and comfortable indoor environment by continuously exchanging stale indoor air for fresh outdoor air.

So, it is normal for an ERV motor to run continuously in low speed to maintain a healthy and comfortable indoor environment. If you are concerned about the motor's operation or notice any unusual noises or performance issues, it's best to contact a licensed HVAC technician to diagnose and resolve the issue.