Sound Testing Chamber

For Super-Quiet High Wall & Ceiling Cassette Water Fan Coil Units

Extremely quiet in comparison to all other brands and models of high-wall and cassette water fan coil units, the Chiltrix hydronic fan coil units are tested throughout the design iteration phase in the most accurate way possible, and the final products are tested for conformity.

In this process, a free-field setup isolates direct sound for precise, reflection-free analysis. Sound measurements are performed in our factory’s own on-site hemi-anechoic chamber (shown below).

Sound testing is in accordance with GB/T 9068-1988 (Determination of sound power levels for noise emitted by heating, ventilating, and air conditioning equipment – Engineering method) as specified in Appendix C of GB/T 19232-2019, which details the noise testing procedures for fan coil units. Tests are conducted at rated airflow and static pressure, with measurements taken at multiple microphone positions around the unit to calculate A-weighted sound power levels in octave bands. This process aligns with ISO 3744:2010 (engineering method for free-field over reflecting plane), which GB/T 9068 adapts for HVAC. The procedure ensures directional accuracy for noise emission, differing from reverberant methods by isolating direct sound.

Sound Level Table

What are Decibels?

A decibel is a comparative level of sound pressure. The scale is logarithmic.

• 0 dB is not “no sound,” just as a 0 on the Richter scale isn’t “no movement.” It is a baseline reference for the very quietest sound the human ear can hear.
• A 10 dB increase is 10 times more intense, just as each step on the Richter scale represents a tenfold increase in the shaking.
• A 20 dB increase is 100 times more intense, not 20 times more.

So what is dB(A)? The “A” in dB(A) (A-weighted decibels) indicates a filter that mimics human hearing, giving less weight to very low and very high frequencies, with emphasis on what a human can hear. A 1 dB increase is often described as the smallest human-perceptible change in volume. A 10 dB increase is generally perceived as a doubling of the loudness. Below are some common sounds and their typical decibel levels.