How to Check CFM HVAC?

Anemometer: A device used to measure airflow velocity.
Measuring Tape or Ruler: To measure the dimensions of the duct.

Checking the CFM (Cubic Feet per Minute) of your HVAC system involves measuring the airflow to ensure proper system performance. Here's how to do it:

Steps to Check CFM:

Determine Air Speed: Use an anemometer to measure the airspeed in feet per minute (FPM) flowing through the duct.
Measure Airflow: Hold the anemometer in the duct, aligning the vane wheel with the airflow direction to get an accurate reading.
Calculate Duct Area: Measure the cross-sectional area of the duct in square feet (ft²). For a rectangular duct, this is width (in feet) x height (in feet). For a round duct, it's πr², where r is the radius (in feet).
Calculate CFM: Multiply the airspeed (FPM) by the duct's cross-sectional area (ft²) to calculate the CFM.
- CFM = Airspeed (FPM) x Area (ft²)

Example:

Let's say you measure an airspeed of 800 FPM in a rectangular duct that is 1 foot wide and 0.5 feet high.

Duct Shape: Use the correct formula for calculating the area based on the duct shape (rectangular, round, etc.).
Multiple Readings: Take multiple airflow readings and average them for a more accurate CFM calculation.
Professional Assistance: If you're uncomfortable performing these measurements, it's best to consult with an HVAC professional. They have specialized tools and expertise to accurately assess your system's airflow.

Checking CFM is crucial for diagnosing issues such as:

Restricted airflow: Low CFM could indicate clogged filters or duct obstructions.
Oversized or Undersized System: Incorrect CFM can mean your HVAC system isn't properly matched to the space it's heating or cooling.
Poor System Performance: Inadequate airflow results in uneven temperatures and reduced efficiency.

By accurately measuring CFM, you can ensure your HVAC system operates efficiently and effectively, providing optimal comfort and energy savings.