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Thread: How loud are tankless hot water heaters, Noritz NRC98?

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    DIY Senior Member lifespeed's Avatar
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    Default How loud are tankless hot water heaters, Noritz NRC98?

    I am contemplating getting a tankless hot water heater, the Noritz NRC98 would be a likely candidate. The obvious install location in my house would be the master bedroom closet as it shares a wet wall with the two bathrooms.

    How much noise do these things make? The closet has doors, and the bathroom shower could be louder than a hot water heater. But I have never had one, so it makes sense to ask about the noise factor.

    Thanks,

    Lifespeed

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    In the trades Dana's Avatar
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    Quieter than your refrigerator, louder than a snoring mouse in the next room. The shower in the adjacent room will drown out the sound of the heater itself by a considerable margin.

    The loudest they get is usually the flue-purge at the end of a burn when the blower runs full speed for a few seconds, at which point it might approach refrigerator levels if you're in the closet with it. I have a similar sized Takagi in the basement under my bathroom, adjacent to the master bedroom, with the vent 5' from the window, and in the bedroom I can't hear it running unless it's dead-quite in the house, with no water running in that bathroom, and even then I have to listen carefully. There's nothing separating me from the unit other than the subfloor & flooring, and what I hear most readily is the the faint sound of the flue purge cycle coming through the window.

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    DIY Senior Member lifespeed's Avatar
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    Thanks, that is encouraging news despite the fact I might go with a brand different from your experience. I had thought the gas burner itself would be rather noisy, but it sounds like that is not the case.

    My wife was getting cold feet based on the sound of our tank water heater in the garage. She says that is loud enough she wouldn't want something like it in our bedroom closet. And that is just the sound of the burner, of course. But the flue is exposed sheetmetal, and the burner is just behind a thin steel shield, so perhaps the tanked heater is noisier than a good tankless . . .

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Closed combustion devices tend to be a lot quieter than 'open' burners. My boiler is all but inaudible 3' away when running, a good tankless should be in the same ballpark.

    Each of them will typically have sound level information listed on their spec sheet.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    In the trades Dana's Avatar
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    Quote Originally Posted by lifespeed View Post
    Thanks, that is encouraging news despite the fact I might go with a brand different from your experience. I had thought the gas burner itself would be rather noisy, but it sounds like that is not the case.

    My wife was getting cold feet based on the sound of our tank water heater in the garage. She says that is loud enough she wouldn't want something like it in our bedroom closet. And that is just the sound of the burner, of course. But the flue is exposed sheetmetal, and the burner is just behind a thin steel shield, so perhaps the tanked heater is noisier than a good tankless . . .
    Most tank type burners are comparatively loud, since there's direct acoustic contact between the room air and both the burner (which uses room air) and the exhaust (which has a draft hood sucking in room air to dilute the exhaust to limit condensation in the flue.) Forced draft tanks are even worse due to the blower noise.

    Even though the Noritz has 5x the burner of a tank, it's only acoustically connected to the great outdoors. Since they're marketed primarily to a luxury market they take pains to reduce noise where possible. (Takagi is a slightly more down-market vendor in some people's eyes- Noritz & Rinnai are the top-dogs.)

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    DIY Senior Member lifespeed's Avatar
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    Got the new Noritz NRC-1111DVNG installed. I love it! It is much easier to use hot water at the faucets at 120 degrees rather than the excessive 140 degree setting of a tank heater (set hot to increase 'capacity').

    I am amazed at how quiet it is. Even when I am in the attic sitting right next to it I can barely hear it. Directly underneath it in the bathroom I can't hear it at all.

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    In the trades Dana's Avatar
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    You're not listening hard enough. On a windless day, turn everything off in the house, turn the hot water on in the kitchen THEN go into the bathroom , close the doors so you don't hear the water splash in the kitchen, then listen while holding your breath- bet you'll hear at least something. :-)

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    OK, I can hear something. I think slight vibration from the fan is transmitted through the studs in the attic it is mounted to, probably some transmission through the pipe connections too.

    Still, a very quiet unit.

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