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Thread: How quiet is a Rinnai tankless, *really*?

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    DIY Member dimprov's Avatar
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    Default How quiet is a Rinnai tankless, *really*?

    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
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    Last edited by dimprov; 02-22-2009 at 06:59 PM.

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    DIY Member dimprov's Avatar
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    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
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    DIY Senior Member BimmerRacer's Avatar
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    I have an R85i in my basement. Send me a decibel meter and I'll measure it for you . I will, however, say that it's pretty quiet. HTH

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    DIY Member dimprov's Avatar
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    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

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    DIY Senior Member BimmerRacer's Avatar
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    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

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    DIY Member dimprov's Avatar
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    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

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    DIY Member dimprov's Avatar
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    Thanks for the correction, BimmerRacer. I thought it was your initials.

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    DIY Member dimprov's Avatar
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    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 by dimprov; 03-05-2009 at 08:25 PM.

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    Illinois Licensed Plumber SewerRatz's Avatar
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    Quote Originally Posted by dimprov View Post
    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 wont my heart and I'm buying Navien as soon as I can verify their claim.


    David
    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.

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    DIY Senior Member zl700's Avatar
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    "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.

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    Electrical Engineer jdf405's Avatar
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    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.

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    DIY Junior Member gatorays's Avatar
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    Default rinnai 94

    Quote Originally Posted by jdf405 View Post
    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.
    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?

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    Homeowner Thatguy's Avatar
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    Post your honk on YouTube. That may motivate Rinnai to publish a Technical Service Bulletin on how to fix this.

    Sounds like water hammer. Try taking 5 seconds to turn the water off.
    Also, put your hand on the pipes during normal shutoff and see if it changes the sound.

    http://www.google.com/search?q=rinna...i&cr=&safe=off
    Last edited by Thatguy; 10-28-2010 at 07:22 PM.

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