The quietest ERVs and HRVs, by the makers' own noise figures

Three yardsticks, and none converts to another

The ERV and HRV makers that publish noise split three ways: sones at a test static pressure, sones at a stated distance, and sound power in dB(A).

Sones at a test static pressure is how bathroom fans are rated under HVI 915. Panasonic rates the WhisperComfort 60 this way, at 0.1 and 0.25 inch of static pressure. VENTS-US also gives the Frigate ERV 80 a sone figure at 0.2 inch, with a footnote that it is not HVI certified.

Sones at a stated distance cover the single-room units from VENTS-US and Blauberg, plus one Blauberg ducted unit, at 3 ft, 10 ft, 1 m or 3 m. Distance moves the number a long way. On the same speed, VENTS lists the TwinFresh Expert RA1-50-2 at 0.3 sones at 10 ft and 0.6 sones at 3 ft.

Zehnder publishes sound power in dB(A), the A-weighted sound emitted by the casing, at ten airflow and pressure points. Sound power describes the source, not what reaches your ear at a given spot, so it cannot be set against sound pressure or sones.

No sone figure is converted to decibels here, and no yardstick is ranked against another. Inside each group, every figure comes with the airflow it was taken at. Without that, a figure says almost nothing.

Are through-wall ERVs the quietest?

They post the lowest sones-at-a-distance figures in this guide, and they also move the least air.

A through-wall unit sits in the room and breathes through a single hole in an exterior wall. It reverses direction every minute or so, storing heat in a ceramic regenerator between swings. The TwinFresh Comfo RA1-50-2 is rated 0.2 sones at 10 ft at 12 CFM in ventilation mode.

Read the airflow column twice.

VENTS lists two airflows for each speed: ventilation mode, and a lower regeneration mode, which is the heat recovery mode you would actually run in winter. At top speed the Comfo moves 30 CFM in ventilation mode but 15 CFM in regeneration mode. The TwinFresh Expert RA1-50-2 manages 9 CFM and 4 CFM at speed 1. These are single-room products; one Comfo can serve a room of up to 500 square feet, according to VENTS.

Transparency is a problem too.

VENTS's TwinFresh Expert datasheets carry two tables for the same unit, and they disagree: one gives 0.6, 1.0 and 1.2 sones at 3 ft, the other 0.3, 0.3 and 1.3 sones at a stated 0.03 inch of pressure. Blauberg North America sells a unit with identical published power, airflow and speed figures, the Vento Expert A50-1 Pro, and lists the 0.6, 1.0 and 1.2 sones with no distance at all. Every version is quoted on the product cards.

Panasonic rates one ERV the way it rates bath fans

The WhisperComfort 60 is rated 0.9 sones at 40 CFM, 1.5 sones at 50 CFM and 2.5 sones at 60 CFM, all at 0.1 inch of static pressure.

Few makers disclose bathroom fan noise as fully as Panasonic does. In ERVs it publishes a sone table for exactly one product, this one, and the table is a good one, with figures at the tougher 0.25 inch pressure as well. Ceiling or wall mounting and two 4 inch ducts let it go where a through-wall unit cannot. It is not for use in a bathroom, Panasonic states; for the bathroom itself, our bathroom exhaust fan guide ranks Panasonic's fans on the same kind of sone table.

The larger Intelli-Balance and BalancedHome ERVs get no sone figure in any submittal or catalog page we opened. The Intelli-Balance 100 sell sheet even quotes the ASHRAE 62.2 requirement for whole-house ventilation "with sones not to exceed 1.0" without saying how loud the Intelli-Balance itself runs.

How loud are whole-house ducted ERVs?

The fullest published table belongs to Zehnder's ComfoAir Q350: casing sound power from 34 dB(A) at 88 cfm and 25 Pa up to 52 dB(A) at 206 cfm and 200 Pa.

Zehnder America's ComfoAir Q guide prints airflow, static pressure, watts and casing sound power for each of the Q350, Q450 and Q600, and in doing so it also shows what duct resistance costs in decibels. Hold the Q350 at 147 cfm and it reads 43 dB(A) at 100 Pa, 47 dB(A) at 200 Pa.

Two smaller ducted units carry sone figures. Blauberg's ERV EC D 130 is rated 0.6 sones at 3 m at 63 CFM and 0.2 inch, and 2.2 sones at 3 m at 116 CFM and 0.4 inch. The Frigate ERV 80 from VENTS-US is listed at 1.4 sones at 30 L/s and 0.2 inch.

With any ducted unit, the figure describes the cabinet. What reaches a bedroom depends mostly on the ducts: their size, their length and the air speed at the registers. Build Equinox's CERV FAQ is direct about it: "restrictive ductwork can lead to higher air velocity resulting in more duct noise."

The big ducted brands publish nothing

Broan-NuTone, Panasonic's Intelli-Balance and BalancedHome lines, AprilAire, RenewAire, Lifebreath, Honeywell Home, Fantech and Build Equinox give no noise figure in any of the documents below.

Some retailer listings quote sone and dBA figures for the AprilAire V22BEC. None of those numbers appears in an AprilAire document we could find, so they are left out.

A missing figure does not prove a unit is loud. It does mean you cannot compare it, and the installer should be asked for the maker's sound data before you buy.

How do you choose a quiet ERV or HRV?

Start with the job. For one or two rooms without ducts, a through-wall ERV gives the quietest published figures, at small airflows.

For a whole house, a ducted unit in a mechanical room keeps the fan out of living space, and the ductwork decides what you hear. The core type does not set the noise; the fans, speed and ducts do. What the core decides is what gets recovered: an HRV recovers heat only, while an ERV also moves moisture between the air streams, which suits humid summers or very dry winters. Choose the core for your climate, then compare noise figures within the same unit and distance.

A whole house fan is a different tool. It cools the house through open windows at night rather than trickling fresh air in all day.

Then size the unit so it can run at a low continuous speed. Every multi-speed unit here gets louder as airflow rises, often by a lot: the TwinFresh Expert RW1-85-2 V.2 goes from 0.5 sones at 9 CFM to 2.1 sones at 50 CFM, both at 10 ft.

A bigger unit loafing at a third of its capacity will be quieter than a smaller one flat out.