Balancing a HVAC System with Multiple Diffuser Types

The Problem

  • Standard air flow hoods do not correct for diffuser type when balancing a system.
  • Proportional balancing is extremely difficult when a mixture of diffusers are present, due to the inaccuracy of standard hoods on slot diffusers.
  • Below is a sample of diffusers tested on Dwyer’s Precision Air Calibration Station (Figure A) with a standard air flow hood followed by the Dwyer SMART Air Hood™ Balancing Instrument (Series SAH).

Figure A: Precision Air Hood Calibration Station
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Air Velocity and Flow Measurement with Pitot Tubes

Dwyer Instruments offers many styles of Pitot tubes, which are a commonly used sensor  for monitoring air velocity and flow rate in heating, ventilation, and air conditioning.

Pitot tubes are based on Bernoulli’s equation, which states an increase in the speed of a fluid occurs simultaneously with an increase in dynamic pressure and a decrease in static pressure.  Pitot Tubes sense the dynamic pressure of the fluid flow at a particular point and were invented by French Engineer Henri Pitot in the early 18th century.

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Mystery Solved! Dwyer Solves the Wall Mount- Relative Humidity Error Problem

Wall mount humidity sensors for building automation system (BAS) applications are produced and sold by several different companies and have a reputation of poor accuracy despite specifications from suppliers. There is a rational reason why these instruments appear to read outside of their stated accuracy, which in turn causes users to be frustrated with the results.

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