First off, thanks for your patience and assistance. I'm less than a year out of school working my first engineering job so applying the concepts learned in school is still a struggle. Much easier when a textbook tells you exactly the variables you need.
Here's what I found for fan affinity...
OK, I can see how fan affinity laws would be preferred. In fact, that's where I came up with fan power being proportional to the cube of fan speed. I see that head or pressure is proportional to the square of fan speed, so that will allow me to get from change in pressure to change in fan...
I have a question regarding the relationship between airflow restriction and fan power. If the pressure drop across an airflow restrictor (filter bank, heat exchanger coils, etc.) is known by measuring with a magnehelic differential pressure gage and that dP changes (filter replacement/removal...