What external static pressure is required for a large commercial rooftop unit?
What External Static Pressure Is Required for a Large Commercial Rooftop Unit?
There is no single external static pressure value that applies to every commercial rooftop HVAC system.
Required ESP depends on the resistance of the complete external air-distribution system connected to the rooftop unit.
Typical Sources of Pressure Loss
- Supply ductwork
- Return ductwork
- Filters
- Elbows and transitions
- Fire or balancing dampers
- Fresh-air sections
- Diffusers and grilles
- Sound attenuators
- Other external air-treatment components
A rooftop unit may provide the correct cooling capacity but still perform poorly if the fan cannot deliver the required airflow at the actual system resistance.
Better Selection Question
Instead of asking only “How many CFM can the unit provide?”, ask “How many CFM can the unit provide at the required external static pressure?”
YUJU can review airflow and duct-system conditions as part of project-based large RTU selection.
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