Total external static is above the fan rating and delivered airflow is low. Which restrictions and setup conditions should be investigated?
- ARemove safety controls for the described HVAC equipment and measured operating conditions
- BAdd refrigerant
- Filters, coils, dampers, duct restrictions, and fan setup
- DIncrease gas pressure
Why C is correct
The best answer is: Filters, coils, dampers, duct restrictions, and fan setup. High static indicates resistance or incorrect setup on the air path. Increasing speed without finding the restriction can overload the motor and worsen noise or leakage. The transferred operating condition requires the same design, installation, diagnostic, or safety principle in a different HVAC context. The other choices skip a prerequisite, conflict with the listed procedure, or treat a symptom without controlling its cause.