HVAC Measurement Types and Benefits

Eric Kaiser joins the HVAC School podcast to talk about HVAC measurement types and the benefits of taking each one. He also talks about point measurements and data trends.

Point measurements include static pressure, voltage readings, and readings provided by gauges. We only take those measurements once. However, when you track those on several occasions over time, you can build data trends. Single-point measurements give us information about what is happening at the moment, but they don’t give us a long-term view of the system's health.

Absolute and differential measurements also have different purposes entirely. Absolute measurements require us to compare a reading to a specific, unchanging reference point, but differentials compare one measurement to another.

When we turn point measurements into trend measurements, we can see some degree of causation. Changes in data trends indicate that a problem occurred at a certain point in time and could be due to changes that coincided with the deviation from the norm. However, that’s intermittent trending that relies on us to take point measurements at spaced-out points in time. Continuous trending allows us to use sensors and test instruments that map changes constantly.

At the end of the day, point measurements are like snapshots, and continuous data trends are like videos; the former only shows part of the picture, and the latter can help us solve more difficult problems by giving us a more complete idea of what’s happening.

Eric and Bryan also discuss:

• Qualitative vs. quantitative measurements
• Filter restrictions and static pressure
• Gauge vs. atmospheric pressure
• Combined trend measurements
• How tool usage and calibration impact measurements
• Non-invasive testing
• Recorded data and sample frequency
• Comparative troubleshooting in spaces with similar equipment
• Resolution vs. accuracy vs. precision

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