Which booster pump is quietest?
DAB's E.SYBOX carries the lowest booster pump figure we found, 43 dB(A) of sound pressure at 1 meter in free field. That ranks it only against the E.SYBOX Mini 3, rated 45 under the same footnote.
The four figures, each as its maker printed it:
- DAB E.SYBOX: 43 dB(A), sound pressure at 3.2 ft (1 meter) in free field
- Grundfos SCALA2: 44 dB(A) in typical use, at 1 m3/h and 19 m of head, ISO 3745
- DAB E.SYBOX Mini 3: 45 dB(A), sound pressure at 3.2 ft (1 meter) in free field
- Franklin Electric VersaBoost Pro: 45 dB, no weighting, distance or flow given
The spread is 2 dB from top to bottom. Between the two DAB pumps that gap means something, because one footnote covers both. Between makers it means nothing, since the SCALA2 has no stated distance and the VersaBoost Pro has no stated anything.
Why are DAB's booster pumps ranked apart from Grundfos and Franklin Electric?
DAB's two booster pumps share one measurement note, sound pressure at 1 meter in free field, in one 2019 US catalog. Grundfos and Franklin Electric state different conditions or none, so their figures stand alone.
Grundfos names a standard, ISO 3745, and an operating point: 1 cubic meter an hour against 19 meters of head. Its booklet never says how far from the pump the microphone was. A second footnote in the same booklet describes the test point as pressure control mode at 2.5 bar and 1 m3/h instead.
Franklin Electric prints 45 dB in a specification table with no A weighting, distance or flow. Its web page says "as low as 45 dB", which suggests the pump reads higher at other duty points. With no conditions given, there is nothing to line that number up against.
Are booster pumps loud?
No, not on their makers' paper: the four residential boosters here are rated 43 to 45 dB. Those figures come from light duty or typical use, though, and no maker publishes a level at full flow.
A booster runs harder when several fixtures are open at once, and none of these makers says how much the level rises then. Grundfos's ceilings for its other boosters hint at the range: the SCALA1, which lacks the SCALA2's integrated frequency converter, is listed at under 55 dB(A), and the MQ at under 70.
Placement matters as well. A pump bolted to a joist or a hard floor passes vibration into the house. Grundfos sells a stand for the SCALA that it says reduces vibration and noise, and DAB and Franklin Electric both fit anti-vibration or rubber feet.
Is there a silent booster pump?
No, no maker here rates a booster pump at zero, and "silent" appears only in marketing copy beside figures of 44 and 45 dB(A).
DAB's US page for the Mini 3 says managing water pressure "has never been so simple and silent", while DAB's catalog rates that pump at 45 dB(A).
Grundfos's booklet writes that the SCALA2's water cooled motor and sealed bearings ensure "silent operation", in the same sentence that gives 44 dB(A). An earlier DAB US leaflet called the E.SYBOX "whisper-silent", at 45 dB.
Read those words as a maker's description of a quiet pump, not as a measurement. What a booster pump actually reaches is in the figures above, and every one is above zero by a wide margin.
Why is my booster pump noisy?
The booster pump noises the makers' manuals describe are a click from the self-priming valve at each start, trapped air in the pump body, and worn bearings. The first two can usually be fixed during installation.
Grundfos says the SCALA2 may click when the water at its inlet is already under pressure, and offers a locking pin to stop it. DAB describes the same click on the E.SYBOX and Mini 3 and explains how to force the recirculating pipe closed. In both cases the pump loses its ability to self-prime, so this suits mains boosting only.
Franklin Electric's manual tells owners who hear excessive noise to open the priming port slightly, at a low pressure setting, until water flows and the air is gone. Its troubleshooting table lists audible noises from worn bearings as a job for the dealer.
What is the quietest well pump?
No well pump we checked carries a maker decibel figure, including DAB's E.SYBOX Diver, a 7 in. submersible built for wells and tanks. Its US technical sheet prints none.
A shallow well is a different case. All four boosters here can draw water from below the pump: DAB's two and the Grundfos SCALA2 from 26 ft, and Franklin Electric's VersaBoost Pro from 25 ft. For a well that shallow, one of these could do the job of a jet pump, with a maker figure behind it.
Deeper wells need a submersible pump down the casing, where most of its noise stays underground.
Do Pentair, Goulds and Davey print booster pump decibels?
No, Pentair, Goulds and Davey print no noise figure in the US booster documents we read, and Grundfos gives only ceilings for its SCALA1 and MQ.
Pentair's US page and data sheet for the Sta-Rite R Series IntelliBoost give pressure, flow and protection features but no decibels. The ResiBoost FAQ from Goulds Water Technology covers tanks and wiring without a sound level.
Davey's US DynaDrive datasheet lists "Low noise output" and "Economical and quiet running", but the USA datasheets for the BT Series, DynaDrive and EvoDrive print no figure. For the Grundfos SCALA1, the booklet's "< 55" dB(A) is an upper limit; for the MQ, Grundfos's US instructions print "< 70".
