A heat pump water heater bolts a compressor and fan onto a tank, which is why the category has a noise problem, and why it has become the rare appliance aisle where makers publish decibels and argue about them. GE runs a chart against the leading competitor's 45. AO Smith calls itself the quietest on the market. Rheem footnotes its measurement distance.
Sixteen models across eight brands carry maker figures, from GE's 41 dBA floor to the 55 dBA Rheem prints for its own 120V plug-in.
Same number, different meanings
Every maker but one publishes a bare or lightly conditioned dBA. Rheem, Ruud and Richmond, three badges on one platform, attach the best footnote in the class: 45 dBA "measured at 6.28 feet using third-party certified testing procedures". GE names a specification, NEEA Advanced Water Heating Specification 8.1, for its 41, but says "as low as", the floor of a variable speed compressor. AO Smith's 45 comes with nothing at all. Bradford White commits only to "less than 50 dBA".
Stiebel Eltron alone publishes the full picture: "Sound power level* 60 dB" and "Sound pressure level* @ 3.3 feet (1 m) 52 dB(a)", plus a footnote explaining the difference. That honesty costs it the comparison: 52 at 1 meter against 45 at 2 meters is not a 7 dBA gap, it is two different measurements, per our sound power vs sound pressure explainer and why you cannot compare dB ratings across brands.
The 41 against 45 fight
GE's GeoSpring page claims the class lead at "as low as 41 dBA" and its brochure repeats "Quiet operation at just 41 dBA." AO Smith's Lowe's line claims the "Quietest Hybrid Electric Heat Pump on the market at 45 DBA" at the same time. Both cannot be right, and on published numbers GE wins, with the honest caveat that a floor figure and an unconditioned constant are hard to referee. What the fight itself proves is better news: this category considers quiet worth competing on, which is more than the refrigerator aisle can say.
The 120V plug-in trap
The new 120V plug-in hybrids solve an electrical problem, no 240V circuit needed, and Rheem's spec sheet quantifies the acoustic cost: its 120V dedicated circuit unit prints "55" in the sound level column, ten dBA above its own 240V claim, because a compressor with no backup elements must work harder. AO Smith claims its 120V Voltex matches its 240V unit at 45 dBA, GE's line wide floor covers its 120V models, and nobody else numbers their 120V units at all. If the tank lives near living space, the 240V hybrid is the safer acoustic bet, and Rheem's own disclosure is the evidence.
What we could not use
LG's press release claims "a quiet sound level of just 42 dB(A)" for its inverter unit, and per mode figures of 42 and 45 dBA circulate on distributor submittal sheets we could not retrieve from LG itself, so only the press release line is quoted. SanCO2 publishes 37 dB for a split system whose compressor sits outdoors, a different architecture that sits outside this ranking. And the ENERGY STAR database, useful for cross checking efficiency, carries no noise data at all.
We did not measure any of these water heaters. Every figure is the maker's own, quoted as published, with the condition attached wherever the maker attached one.
