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I was called out to provide a solution to the noise of a 2019 water heater. It is an AO Smith BTH-400A installed in the basement of a 23 unit multifamily complex. We did not spec or install the heater so we are in a good position to provide the solution. The building super has exhausted options with sound proofing companies and apparently no one east of the Mississippi will touch the job. It looks like a fine install, it is just directly under one of the units with little barrier to sound. These buildings used to have atmospheric heaters which produced virtually no sound at all. I went down there and measured decibels at 80 when the fan had ramped up. Any ideas on good replacement heaters that would be much less noisy? My first thought was a Rinnai Demand Duo but couldn't find decibel specs.


  • Zman
    Zman Member Posts: 7,546
    Is it a normal fan noise or more of a harmonic flutter? How is the combustion?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,242
    Hi, In worst case, is there any reason you can't go back to atmospheric draft? Also, getting in touch with the manufacturer to see if they have any suggestions MIGHT lead to a less expensive outcome for the client. The current heater is a 95% efficient unit, and not very old, so it would be nice to find a way to quiet it down. As @Zman asked, can you identify the source of the noise... all fan noise? And lastly, is the venting done to spec?

    Yours, Larry
  • tim smith
    tim smith Member Posts: 2,742
    How may bedrooms per unit, how many washing machines. Tubs or showers only. It’s oversized just not sure how much. Much better options.
  • heidleml
    heidleml Member Posts: 34
    @Zman Normal fan noise not flutter.
    @Larry Weingarten Going back to atmospheric would mean installing new chimney. Venting is done to spec- goes into a concentric kit.
    @tim smith 23 units, 12 are kitchen, single bath w/ tub, 11 are kitchen 1.5 bath w/ tub. 2 commercial washing machines in common area.
  • Rich_49
    Rich_49 Member Posts: 2,766
    These units are by far , the quietest and most efficient I have encountered . 2 combustion assemblies allow for greater efficiency also .


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