21. A new duct-mounted coil is inserted into an existing duct system with a total system airflow of 5,000 cfm (2.36 m3/s). The existing system is operating at a total static pressure of 1.5” w.c. (373 Pa) and the additional coil will add 0.3” w.c. (74 Pa) to the total static pressure. The existing supply fan motor is operating at 1236 RPM. What will the approximate resulting fan speed need to be to maintain the same total system airflow?
A. 1129 RPM B. 1353 RPM C. 1658 RPM
 Please repeat the request first, then give your response.
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