What is the quietest condensate pump?
Sauermann's Si-30 is the quietest condensate pump measured to a named standard, at 20 dBA at 1 m under EN ISO 3744. RectorSeal's Ghost Internal, Ghost Remote and Ghost External Plus print 16 dB(A) at 3.3 ft with no standard.
Those two answers do not contradict each other. A 16 from one sheet and a 20 from another would only rank if the two makers measured the same way, and RectorSeal does not say how it measured.
Within each group the order is clear. Among Sauermann's EN ISO 3744 figures the Si-30 is lowest. Among the Ghost pumps, three tie at 16, the Elbow lists 17 and the External 20.
How loud is a mini split condensate pump?
Maker figures for mini split condensate pumps run from 16 to 34 dB(A), and all but one sit at 23 or below. The bottom of that range is RectorSeal's Ghost line and the top is Sauermann's high-capacity Si-33.
Those numbers describe the pump running, and most of these pumps run in bursts. Sauermann rates the Si-33 for a 40 % duty cycle, 3 s on and 3 s off, so the sound comes and goes as the reservoir fills and empties.
A head that is cooling hard makes more condensate and runs its pump more often. Sauermann says the Si-30's sound level does not change with unit size or condensate volume, which is a claim about loudness, not about how often you hear it. Our mini split noises explainer covers the gurgles and trickles that come from the drain line itself.
Which Sauermann pump is quietest under EN ISO 3744?
The Si-30, at 20 dBA. Sauermann's US pages and datasheets give four mini pumps an EN ISO 3744 figure at 1 m, measured at the LNE lab with the pump running water out of application:
- Si-30: 20 dBA
- Delta Pack kit: 22 dBA
- Si-10: 23 dBA
- Si-33: 34 dBA
The Delta Pack is built around an Si-10, yet its sheet says 22 where the Si-10's spec table says 23. The Si-10 datasheet's own front panel also says 22 dBA "at full power". Sauermann does not explain the one decibel gap.
The Si-33 is the outlier because it is the big pump of the range, moving 8 gph for units from 20 kW up to 30 kW. Its datasheet prints the 34 as "≤ 34 dBA", while the US page prints a plain 34.
Why can't the Ghost's 16 dB(A) be ranked against Sauermann?
Because RectorSeal names no test. Its submittals say "16dB(A) @ 3.3ft (1M)" and "Sound level and pump performance varies with voltage frequency," and stop there, while Sauermann names EN ISO 3744, the lab and the operating state.
Two figures at the same distance can still differ by how the pump is mounted, what water flow it is pumping and what background noise the room has. EN ISO 3744 fixes those choices; a bare distance does not. So the Ghost figures rank only against each other.
On that basis the Ghost Internal, Ghost Remote and Ghost External Plus tie at 16 dB(A). The Ghost Elbow lists 17 and the Ghost External 20.
Why do older RectorSeal sheets list higher numbers?
The Ghost pumps reuse product codes RectorSeal once sold under the Aspen name, and the old sheets list higher figures. Code 83809 was the Aspen Mini Aqua Univolt at 21 dB(A); 83909 was the Mini Orange Univolt at 26.
The Aspen Mini Lime OEM Univolt, code 83869, listed 25.5 dB(A); the Ghost Elbow under that code lists 17. None of the Aspen sheets gives a distance, and none names a standard.
RectorSeal's Aspen series pages still carry those sheets but list no items, while each Ghost page shows the same code under the Ghost brand. The Ghost External Plus page goes further and links both its 16 dB(A) Ghost submittal and the older Mini White Silent+ sheet for code 83930, which says "19dB(A) @ 3'".
RectorSeal does not say whether the pumps changed, the test changed, or both. We quote the Ghost sheets because they are the current ones.
Which condensate pumps list decibels with no distance?
BlueDiamond, DiversiTech, Hartell and Little Giant print a figure with no distance or standard, and so does Sauermann for its slim Si-20. Each of those ranks only within its own maker:
- BlueDiamond MicroBlue X86-003: 17 dB(A)
- DiversiTech QUIETMINI-I: 19 dBA; QUIETMINI-M: 21 dBA
- Hartell HAR-8: 19 dBA; HAR-15: 21 dBA
- Sauermann Si-20: 19 dBA
- Little Giant EC-1-DV: 21 dB(A)
Little Giant's footnote is the most revealing. It says the 21 was "Tested under conditions assumed consistent with competitors' published sound ratings," which reads as an attempt to match other makers' numbers without knowing how they were taken. The EC-1K-DV kit and EC-1U-DV undermount pump carry the same footnote.
Sauermann's Si-20 shows how much the missing distance matters. The same maker that gives the Si-30 a full EN ISO 3744 description prints the Si-20 as "Sound level 19 dBA" alone, so even a 19 from Sauermann cannot be set beside its own 20.
Is there a quiet condensate pump for a furnace or air handler?
No tank pump we checked has a figure we could rank. Little Giant's HVAC catalog prints none for its VCMA, VCL and VCCA tank pumps, and Hartell's residential HAT page gives only "< 48dBA" and "< 26 dBA".
A ceiling says the pump stays under a line without saying by how much, so neither Hartell figure is ranked here. RectorSeal's RTP tank pumps and MARS pumps show no noise figure on its site, and the Aspen M4R tank pumps did not come up on rectorseal.com at all.
That leaves this guide to mini split pumps, the kind that sits beside or inside a wall head, a cassette or a ducted unit.
What makes an installed condensate pump louder?
The installation, according to the makers' own notes. Sauermann's Omega Pack 2 sheet says "Noise level depends on installation conditions and support", and its in-application figures run higher than its bench figures.
The Delta Pack lists 25 dBA in application against 22 out of application, and the Si-33 "≤ 36 dBA" against "≤ 34 dBA". Those are 3 and 2 decibels added by mounting the pump the way it will actually be used.
Sauermann sells the Si-30 with a bracket "specifically designed to reduce vibration transmission to the wall / panel or pipework", and BlueDiamond fits the MicroBlue with rubber mounts. RectorSeal's brochure points to a remote pump for noise sensitive rooms, since the pump body can then sit away from the head.
