Decibels replaced sones
Every current spec sheet in our sweep is in decibels. For a long time this was a sone category, like the bathroom exhaust fans and range hoods it shares an industry with. QuietCool's sheets now carry a per-speed dBA row, AirScape gives a min to max range, Centric Air prints dBA per speed, and Solatube writes plain dB.
Tamarack is the gap. The sone figures still quoted around the web for its fans trace to retailer blogs, while its spec sheet lists airflow, watts and R values and no noise figure at all, which keeps an otherwise interesting fan out of this guide.
Rigor did not survive the switch. Only two figures in the whole category state a measuring distance, both AirScape's, and nobody names a standard for the acoustics, even though the airflow side is properly HVI-916 rated. Our comparing decibel ratings explainer says why that caps what cross brand gaps can prove.
How loud is a whole house fan on low?
These fans run overnight on low, so this guide ranks by the low speed figure wherever one is published, and the low figures are where the category shines.
| Fan | Low | High | Airflow |
|---|
| QuietCool ES-3100 | 33.0 dBA | 47.4 dBA | 2,020 CFM low, 3,081 high |
| AirScape Sierra 3400 | 36 dBA (min) | 52 dBA (max) | 723 to 3,440 CFM |
| QuietCool ES-2250 | 37.2 dBA | 42.7 dBA | not listed here |
| QuietCool CL-2250 | 37.4 dBA | 43.2 dBA | 1,910 CFM low, 2,465 high |
| QuietCool CL-1500 | 37.4 dBA, single speed | | 1,472 CFM |
| Solatube EPS Zone | 40 dB | 48 dB | up to 1,400 CFM |
| QuietCool CL-4700 | 43.2 dBA | 49.4 dBA | 4,415 CFM |
| AirScape Ventura 1700 | 44 dBA @ 1m | 55 dBA @ 1m | up to 1,545 CFM |
| Solatube EPS Plus | 44 dB | 58 dB | up to 2,502 CFM |
| QuietCool CL-3100 | 46.8 dBA | 49.4 dBA | not listed here |
| Centric Air 3.4 | 47 dBA | 49 dBA | 1,409 CFM low, 3,242 high |
On the models that publish both ends, the drop to low is large: the ES-3100 falls from "Hi: 47.4" to "Low: 33.0" and still moves "2,020 CFM" at the bottom. The ECM Energy Saver line also roughly halves the wattage of the AC motor Classics at matched sizes, 79.5 W against 201 W on the 2250s' low speeds.
Some rows repeat suspiciously. The ES-4700 prints the identical "47.4 / 33.0" row as the ES-3100 despite a larger fan, QuietCool's two big Classics share a 49.4 high, and every Centric Air size declares the same 49 and 47. Figures that repeat across different machines read as line-level declarations, and they are ranked here with that grain of salt stated.
Ducted fans start lower than direct ones
AirScape's own numbers show it: the direct Ventura 1700 starts at "44" dBA, where the ducted fans start in the 30s.
Every quiet leader here is a ducted damper box design, with the fan hung in the attic and a stretch of duct between it and the ceiling grille. AirScape's Sierra adds powered R13 damper doors and ships acoustic ducting in the box. QuietCool hangs its heads on suspension with R5 barometric dampers. Solatube uses R6 doors and includes the duct. Direct through-ceiling designs, AirScape's Ventura line and the unrated Tamarack and Cool Attic fans, put the blades at the grille, and that costs them.
The Ventura 1700 still earns its pick. Shallow attics exist, and its "44 to 55 dBA @ 1m" is one of only two figures in the category that says where the microphone stood.
