How quiet is a Rinnai tankless, *really*?

Discussion in 'Tankless Water Heater Forum' started by dimprov, Feb 22, 2009.

  1. dimprov

    dimprov New Member

    Messages:
    38
    Location:
    Austin, Texas
    I'm considering the purchase of multiple Rinnai tankless hot water heaters for a remodelling project where maintaining quiet is one of the design objectives. Rinnai claims its tankless units are quiet, and claims a noise level of 49 db(a) across its range of tankless models--see attached. However, when I look at the Bosch noise level data, it claims a range of 45 to 65 db(a). i.e. a 100x difference in possible sound pressure levels, depending on...? I have no direct experience with either brand, but I suspect the Bosch numbers are more "honest" for common sense reasons: it makes sense that the direct-vent blower on the tankless would make less noise when it is consuming its minimum 19,900 BTU's than when it is burning it's maximum 199,000 BTU's. I therefore suspect that Rinnai's 49 db(a) noise rating is marketing spin and reflects the noise level at the lowest end of its range.

    FWIW, I did contact the local distributor for Rinnai, and he was useless.

    I've come here to get the facts from anyone with actual experience or knowledge of Rinnai units. I can design the soundproofing plan accordingly if I know what I'm dealing with. I can't be shooting in the dark only to find out my assumption is off by 100x because of sleazy advertising!

    David

    Attached Files:

    Last edited: Feb 22, 2009
  2. dimprov

    dimprov New Member

    Messages:
    38
    Location:
    Austin, Texas
    For instance, Eternal gives the "maximum noise" for it's different models, although it's ambiguous as to whether Eternal's db refers to db(a) or some other reference.

    Ideally, I'd like to see the SPL's at different frequencies so I could pick the most appropriate soundproofing materials, but I'm not too hopeful of finding that information, unless someone here has done their own measurements at a 1 meter distance that they're willing to post.

    David

    Attached Files:

  3. BimmerRacer

    BimmerRacer New Member

    Messages:
    174
    Location:
    Washington, DC
    I have an R85i in my basement. Send me a decibel meter and I'll measure it for you :D. I will, however, say that it's pretty quiet. HTH
  4. dimprov

    dimprov New Member

    Messages:
    38
    Location:
    Austin, Texas
    BimmerRacer,

    Does its loudness vary depending upon demand (i.e. maximal versus minimal water heating, such as all taps open versus a single faucet)?

    David
  5. BimmerRacer

    BimmerRacer New Member

    Messages:
    174
    Location:
    Washington, DC
    Just did the test with three sinks going. Yes, it does get louder. How loud? Well, standing right next to it with all three going, it was overpowered by the sound of water hitting the base of plastic utility sink about 10' away. It is also MUCH more quiet than my new Bryant Evolution heat pump and I think that one is rated at 85dB or somewhere near there. Also, do realize that there are different ways to measure sound and it's likely that Bosch, Rinnai, Bryant and everyone else in the world do not follow the same standard. It is sort of like comparing treadwear ratings between Michelin and Bridgestone and purchasing a Michelin because it has a higher treadwear rating and therefore should last longer. Not quite that simple as it turns out ;)

    YMMV
  6. dimprov

    dimprov New Member

    Messages:
    38
    Location:
    Austin, Texas
    Thanks for running the test, YMMV. It proves that loudness varies with demand, and therefore a single number of 49 db(a) can't be right.

    I think I'll assume 49 db(a) is the low end. If the newer Rinnai units manifold the way the older Rinnai units did, then by running 3 Rinnai tankless units in a manifold I can push the aggregate noise toward the lower end of the scale than if I were to use fewer, higher capacity, units.

    David
  7. BimmerRacer

    BimmerRacer New Member

    Messages:
    174
    Location:
    Washington, DC
  8. dimprov

    dimprov New Member

    Messages:
    38
    Location:
    Austin, Texas
    Thanks for the correction, BimmerRacer. I thought it was your initials.
  9. dimprov

    dimprov New Member

    Messages:
    38
    Location:
    Austin, Texas
    The Navien rep told me, and this is a direct quote:
    "The decibel rating of our units range from 25-30. It is much quieter than our competition. You will not hear our burner or fan unless you have your ear up to the unit."

    If true, then they've won my heart and I'm buying Navien as soon as I can verify their claim.


    David
    Last edited: Mar 5, 2009
  10. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,706
    Location:
    Chicago, IL
    I posted about the Naviens a few times, for having a good warranty, a real stainless steal combustion chamber not a copper one surrounded by stainless steal. Also the fact they have models with a built in recirculation pump with a buffer tank. The Recirculation pump can either recirculate the water internally or with a return loop if your home is provided with one. One thing to note is if you use the recirculation pump you need the remote control so you can program when the recirculation pump runs.
  11. zl700

    zl700 DIY Senior Member

    Messages:
    237
    Location:
    Texas
    "One thing to note is if you use the recirculation pump you need the remote control so you can program when the recirculation pump runs"

    Not true, depending on DIP switch setting, the unit will recirc on inlet thermistor at the buffer tank. (Internal or External)

    Connecting the stat/control and provided free with the heater, the control can be programmed to disable the pump, thus stop recirc and heating.
  12. jdf405

    jdf405 Electrical Engineer

    Messages:
    47
    Location:
    Los Angeles Area
    My Rinnai 94LSe that I just installed is amazingly quiet. Its barely audible from 10 feet away and standing right next to it it is still very quiet. Its about 7 feet from a bedroom window and I don't think it will ever cause a sleeping problem.
  13. gatorays

    gatorays New Member

    Messages:
    1
    Location:
    Auburn, AL
    rinnai 94

    I just moved into my house with a 94. I previously had a rinnai and it was very quiet (mounted outside master BR - could not hear it). Now, the one I have in my attic "honks" everytime I turn the hot water off (quiet loud). It is quiet while running, but the honking is driving me crazy. One plumber said it was normal, but did not believe him. If they all made this sound, they would not sell very many. They are still working on it. Any ideas?
  14. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    Last edited: Oct 28, 2010
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