Which air handler is the quietest?
No air handler wins across brands, because no two makers rate noise on the same test. Within its own range, Daikin's FXTQ12 prints 35.9 dB(A) on high, and Fujitsu's AMUH24KUAS 29 on its Quiet speed.
Each maker's lowest figure on its own sheet:
- Daikin FXTQ09 and FXTQ12: 35.9 dB(A) high, 25.9 low, casing radiated, AHRI 260
- Fujitsu AMUH24KUAS: 42 on High, 29 on Quiet in cooling, anechoic chamber
- Durastar DRAM18F1A: 36.5 high, 31.5 low, no basis given
- Mitsubishi SVZ-AP12NL to AP24NL: "36, 41, 45", no speed or basis given
- Bosch IDS Premium BIVB24: 66.9 high, 55.8 low, no basis given
Daikin and Durastar sit close on paper, 35.9 against 36.5 on high, but Daikin names its test and Durastar does not, so those two numbers cannot be lined up. The same goes for every other pair here.
How do air handler makers measure noise?
Only Daikin names a standard, AHRI 260, and only Fujitsu says where it measured, in its own anechoic chamber. Mitsubishi, Durastar and Bosch print a dB(A) row and say nothing about the test.
Daikin's engineering manual for the FXTQ notes: "Sound testing performed in accordance with AHRI 260. Indicated value represents casing radiated sound level." It is the only air handler document we read that gives a standard by name.
Fujitsu's submittals carry the line "Measured values in manufacturer's anechoic chamber" and add that installed levels "might be higher than the specified values here." Neither Fujitsu nor Daikin prints a microphone distance on these air handler sheets.
All five call their figures sound pressure, apart from Bosch, whose sheets say only "Decibels dB(A)". Daikin is the one maker that also prints sound power. Why those two quantities never share a list is covered in our power versus pressure page.
Daikin measures each FXTQ size three ways under AHRI 260: sound radiated by the cabinet, sound at a ducted return, and sound at a ducted supply. Its spec tables and flyer quote only the cabinet figure.
For the FXTQ12 on high speed, the three sound pressure readings are:
- Casing radiated: 35.9 dB(A)
- Ducted inlet: 40.2 dB(A)
- Ducted discharge: 47.2 dB(A)
The supply side is the loudest of the three by more than 11 decibels, which matters if a register sits near a bed. Daikin's flyer rounds the cabinet figure to 36 and calls it "as low as 36 dBA".
The manual's tables also give sound power. On the FXTQ12 that is 44.6 dB(A) for the cabinet on high, against 56.6 at the supply duct.
Are ducted mini-split air handlers quieter than conventional ones?
On paper, yes: on the sheets we read, Daikin, Fujitsu, Mitsubishi and Durastar print 25.9 to 53.8 dB(A) for their ducted mini-split cabinets, while Bosch prints 55.8 to 79 for its IDS air handlers. No maker measures both kinds the same way.
Bosch's own range shows how wide the conventional figures run. Its IDS Light BIVA15-24 lists 63.5 on high speed, its IDS Premium BIVB24 66.9, and its IDS Ultra BIVB19-60 reaches 79.
Bosch's multi-zone capable Edge cabinet, the BIVA VCB, prints one "Rated Speed" figure per size instead, from 45.4 at 1 ton to 58 at 5 tons. That single speed cannot be set against the low, medium and high rows of its other sheets.
Since none of these sheets shares a method with another maker's, a lower number is a hint, not proof. For the outdoor half of the same systems, the central air conditioner guide and the heat pump guide work from AHRI 270 ratings that do compare across brands.
Does a bigger air handler make more noise?
Yes, in every range we read the top figure climbs with capacity. Fujitsu's AMUH lists 42 dB(A) on High at 24,000 BTU and 49 at 48,000; Daikin's FXTQ climbs from 35.9 at 1 ton to 53.8 at 3.5 and 4 tons.
The steps by maker, top speed:
- Fujitsu AMUH, cooling: 42 at 12,000, 44 at 18,000, 42 at 24,000 and 30,000, 44 at 36,000, 49 at 48,000 BTU
- Daikin FXTQ, casing radiated: 35.9 at 0.75 and 1 ton, 44.6 at 1.5 and 2, 51.6 at 2.5 and 3, 53.8 at 3.5 and 4, 50.2 at 4.5 and 5
- Mitsubishi SVZ: 45 at 12,000 to 24,000, 49 at 36,000 BTU
- Bosch IDS Premium: 66.9 at 2 tons, 70.4 at 3, 75.4 at 4, 73.7 at 5
Daikin's two largest sizes read lower than the 3.5 and 4 ton pair, and Bosch's 5 ton sits under its 4 ton. Neither maker explains it.
A cabinet sized to the house's real load, not one size up, is therefore the cheapest noise saving on offer.
Will an air handler sound as quiet at home as on the sheet?
Probably not, and Fujitsu says so: its submittals warn that installed levels "might be higher than the specified values here." Ducts, return grilles and the closet around the cabinet all change what reaches the room.
Daikin's own numbers show part of the reason. The FXTQ12's cabinet reads 35.9 dB(A) on high, but its supply duct reads 47.2, so the register can be louder than the closet.
Trane sells hardware aimed at that gap. Its multi-speed air handler data lists a "Sound Baffle Kit" for 17.5, 21.0 and 23.5 inch cabinets and a "Plenum Stand with Integrated Sound Baffle", though it prints no figure for what either does.
The mini-split guide covers the ductless heads that skip ductwork altogether, if one or two rooms are the real target.
Do Carrier, Trane and Lennox print air handler decibels?
Not as a single A-weighted figure. Carrier prints sound power by octave band for its FE4B fan coil, Trane prints no figure in its multi-speed air handler data, and Lennox makes a "quietest" claim without a number.
Carrier's FE4B product data, edition 11/25, has a table titled "Estimated Sound Power Level of Airflow from Duct (dB)". For a size 24 at 800 CFM it reads 72.0 at 63 Hz down to 53.0 at 4000 Hz, with no overall dB(A).
Lennox's CBA38MV page calls it "The quietest and most efficient air handler you can buy*". The footnote bases that on sound pressure from a CBA38MV-036 against 3 ton units of "the leading competitors", and no decibel figure appears. It is a relative claim, so it stays unranked.
