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  1. #1

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    Hi,
    I am contemplating installing a hot water system with a heat pump.

    However, whilst being efficient in generating heat, the produce 50 to 52 db noise. One of the manufacturers compare this to a comparable level with a refrigerators.

    So, how loud is 50 db?

  2. #2

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    Threshold of hearing 0 dB
    Rustling leaves 20 dB
    Quiet whisper (3 feet) 30 dB
    Quiet home 40 dB
    Quiet street 50 dB
    Normal conversation 60 dB
    Inside car 70 dB
    Loud singing (3 feet) 75 dB
    Automobile (25 feet) 80 dB
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  3. #3

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    Thanks Disko.
    I just was listening to Dr Karl podcast (20/4) via JJJ, and it was said that people will loose hearing after being exposed to 85 db (maximum safe) for more than 8 hrs. Furthermore, each increase in noise level by 3db reduces the "safe" time by half.

    So 88 db 4hrs, 91db 2hrs, 94db 1 hr. 97 db 30 min, 100 db 15 min, 103 db 7 1/2 min, 106 db less than 4 min.

    To give you an idea, a noise level in rock concert could be up to 120 - 130 db.

  4. #4

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    You can't really say 50 db without also including the distance measured from. Doesn't tell you much.

  5. #5

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    Hot water system would be positioned outside the house about 4 m away from master bedroom and 3 m away from family living room, but about 2 m away from a bedrrom of our eldest kid
    (PS, it is a 2 storey house)
    The main concern is the night time when there isn't too much ambient noise

  6. #6

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    I think that would be a similar amount of noise compared with our pool pumps, and man is that noisy when your trying to sleep! - during they day you dont notice it!
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  7. #7
    uncyherb's Avatar uncyherb is offline MacTalk Podcaster

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    <div class='quotetop'>QUOTE(step_andy &#064; May 9 2006, 10&#58;27 AM) [snapback]170885[/snapback]</div>
    Thanks Disko.
    I just was listening to Dr Karl podcast (20/4) via JJJ, and it was said that people will loose hearing after being exposed to 85 db (maximum safe) for more than 8 hrs. Furthermore, each increase in noise level by 3db reduces the "safe" time by half.

    So 88 db 4hrs, 91db 2hrs, 94db 1 hr. 97 db 30 min, 100 db 15 min, 103 db 7 1/2 min, 106 db less than 4 min.

    To give you an idea, a noise level in rock concert could be up to 120 - 130 db.
    [/b]
    Thats true... but only partly true.

    Most concert engineers will measure SPL (sound pressure level) on a A or C weighted scale, which more closely resembles the way the human ear hears: you are less sensitive to lower frequencies than mid-range ones (especially around the 1-4 kHz mark).

    So rock concerts might be 120db unwieghted, but a lot of the energy is below 500Hz and so can be around 90-95dbA (peak) (dbA being the A weighted scale dbC being the C)

    The "safe levels" are generally based on exposure to dbA.

    wiki on a-weighting spl scale
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  8. #8

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    <div class='quotetop'>QUOTE(Disko &#064; May 9 2006, 10&#58;07 AM) [snapback]170878[/snapback]</div>
    Threshold of hearing 0 dB
    Rustling leaves 20 dB
    Quiet whisper (3 feet) 30 dB
    Quiet home 40 dB
    Quiet street 50 dB
    Normal conversation 60 dB
    Inside car 70 dB
    Loud singing (3 feet) 75 dB
    Automobile (25 feet) 80 dB
    [/b]

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  9. #9

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    <div class='quotetop'>QUOTE(Joz &#064; May 9 2006, 10&#58;34 AM) [snapback]170889[/snapback]</div>
    You can&#39;t really say 50 db without also including the distance measured from. Doesn&#39;t tell you much.
    [/b]

    Maybe this little snippet may shed some, further, light on the question. Many years ago I recieved a polite letter from the EPA demanding that I submit my car for noise emission testing (plus receipts for work done between the time I recieved the demand and the testing). They used a microphone on a tripod 1 metre from the exhaust offset 45 degrees for the measurement (with the engine running at 75% of maximum power revolutions; info taken from a large reference manual)

  10. #10

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    I&#39;d say with the window open if you have direct line of sight and you&#39;re like me and notice everything like that you might hear it.

    But building a little brick enclosure for it would kill 50db easy. If practical off course, just run the thing for a night and see (if you&#39;ve bought it already).

  11. #11
    g5agogo is offline MacTalk Podcaster

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    Is this 52 dB SPL at 1 m?

    If so, and given that it is outside, and a few metres from the house, I would say that it shouldn&#39;t be too bad, unless you live in a very quiet street. Having said that, it is possible that the level of noise generated during startup and shutdown could be substantially greater than during normal operation, and could be far more noticeable than a constant lower level hum during normal operation. If so it may be useful to ask about the duty cycle of the compressor.

    Whether it is annoying is somewhat subjective but will also depend to some extent on the house, habits and the environs.
    What is the house constructed of? (timber, brick etc.) Are the walls insulated? Is it older style with vents? What are the location and size of windows near the appliance? What type of glazing?
    Does anyone sleep with the window open?
    What is the usual noise level in the street and environs?

    Also, remember that it isn&#39;t unusual for pumps and compressors to get noisier than spec after a few years operation.

    Hope this helps.

  12. #12

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    Yup, I&#39;m one of those people that can hear a hard drive spinning from the other side of a wall... but I keep earplugs near the bed for the times when something in the distance is bothering me.

    You might want to buy or borrow a sound level meter. Tandy used to sell one for around &#036;70 that does A- and C-weighting and is accurate enough for household purposes. Be sure to get the analogue model, not the digital. It&#39;s more accurate AND cheaper.
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  13. #13

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    If I remember c&#39;rectly, the inverse squared law applies here, so not only do you need the dB (loudness), but how far you are away.

    If the "noise" is measure at 1m, then that same "noise" will be a quarter as "strong" at 2m..... (1/2)^2

    At 3m it will be 1/9 as "strong" .... (1/3)^2 etc

    I use the words "noise" and "strong" very loosely here, but we could be talking loudness etc.

    The inverse squared law applies to other phenomena such as light and strength of radio signals, which is why it is so amazing that we can pick up and interpret signals from spacecraft at the edge of the known solar system.

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  14. #14

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    I thought this was interesting ...

    "Preliminary data on iPods and similar devices have found lower maximum levels -- above 100 decibels (the noise volume of a chainsaw; risk of hearing damage after two hours), but not higher than 115 decibels (a football game in a loud stadium; risk of hearing damage after 15 minutes)"
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