What is the Digital TrueFlow Grid?

We use the Digital TrueFlow Grid, an air handler flow meter made by The Energy Conservatory.

The instrument is a calibrated flow element installed in the filter slot, so it measures the total airflow through the air handler rather than estimating it. (Two other methods are common: reading the manufacturer's fan table against a static-pressure measurement, and calculating airflow from a temperature rise. Both are estimates; static pressure describes resistance, not flow, and the manufacturer states that total external static pressure does not itself measure airflow.)

Manufacturer specifications: accuracy of plus or minus 5 percent in a standard installation, range 300 to 2,500 cubic feet per minute.

Last reviewed 2026-09-06. Accurate to the best of our knowledge as of that date. Rules change — that's why the date is there.