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Q: Central Air Conditioning ( Answered 5 out of 5 stars,   0 Comments )
Subject: Central Air Conditioning
Category: Science > Technology
Asked by: dodomixes-ga
List Price: $25.00
Posted: 18 Jul 2006 12:35 PDT
Expires: 17 Aug 2006 12:35 PDT
Question ID: 747439
What are the quietest central air conditioning systems available?
Specifically 1.5 ton and 2.0 ton in size.
Subject: Re: Central Air Conditioning
Answered By: crabcakes-ga on 18 Jul 2006 15:43 PDT
Rated:5 out of 5 stars
Hello Dodomixes,

    It appears that today's air conditioner units are measured as BTUs
and SEER today, in place of tons. ?Air conditioner sizes are often
given as "tons" of cooling. Multiplying the tons of cooling by 12,000
converts it to BTU/h.?

?Cooling capacity
Manufacturers produce air conditioners in a variety of sizes,
typically measured in "tons" or "BTUs per hour." A BTU (British
Thermal Unit) is a common unit used for measuring heat output, equal
to the amount of energy required to raise one pound of water one
degree Fahrenheit. One ton equals 12,000 BTUs/hour-a term derived from
the amount of energy required to melt 1 ton of ice in a day.

With air conditioners, bigger is not necessarily better. For one
thing, the larger the capacity, the more a unit will cost; output is
directly related to cost. Also, it's critically important to pick a
size that is appropriate for the house. An air conditioner that is too
small can't keep up with load requirements on a particularly hot day.
One that is too large will cycle off and on too frequently, doing a
poor job of dehumidifying the air, which degrades comfort. In fact,
it's better to slightly undersize an air conditioner than to oversize
it. Also, the air flow into and out of rooms must be carefully
balanced to insure efficient operation of the system. These factors,
as well how well a house is insulated, how it's used by your family,
the climate and more must be taken into account when selecting and
designing your system. That's why you should consult a qualified air
conditioning contractor.?

Air conditioners are also rated for sound level.  ?HVAC equipment. If
you're installing a new HVAC system, you have several options for
finding a quiet one. if you're looking for a quiet condenser, choose
an Energy Star qualified system with a nominal sound level of 76
decibels or less. Locate the condensing unit where it will be the most
unobtrusive. Make sure walls or landscaping features do not block
airflow to the unit because that would reduce its efficiency.?

Sound Levels
"Few people think about how loud an air conditioner or heat pump will
be - at least until the unit is installed and running in their back
yard. With some units, the noise created by the condensing unit
outside can even interfere with indoor peace and quiet. That's why you
should compare the sound levels produced by different models when you
are shopping for a new unit.
The sound level of outdoor units is measured in bels (a term similar
to decibels). The rating scale goes from 0 - the rating for a barely
perceptible sound - to 13 - the threshold of pain. Most air
conditioners and heat pumps operate in the range of 8 to 9 bels,
although some are quiet enough to rate as 6.8 bels. (While that may
not sound like a wide range, consider this: the noise output at 9 bels
is 10 times louder than 8 bels. That means one 9-bel air conditioner
is as loud as 10 units rated at 8 bels!)?

?Look for sound-dampening features such as vibration isolation for the
compressor and insulation. Also, louvers or heavy-duty wire grids and
caps protect the unit from weather and impacts from sports or lawn

I think you?ll find many of the newest central air conditioning
systems will meet the 76 db or less criteria. When selecting your
unit, compare prices, BTUs and sound levels.

?If you are looking for a good, basic central AC unit, the Amana
Prestige Ultra RCE (*est. $2,150) is an excellent choice among 14 SEER
single-stage systems (more on SEER below), but this unit still uses
R-22 (Freon). Amana includes a ten-year warranty on the compressor and
coils and five years on all other parts, and reviews say it's quiet
and efficient at its single speed. However, the Rheem Classic 14 (also
sold as the Ruud Achiever Series 14) doesn't cost much more (*est.
$2,500) and uses the more ozone-friendly Puron. This single-stage unit
also is rated at 14 SEER, with a similar warranty of ten years on the
compressor and five years on other parts. Plus, since the Rheem uses
Puron, parts and the refrigerant itself will be readily available
should your unit eventually need repair.?

The Carrier Performance 14 purports 69 decibels

Here is a decibel chart comparing sound decibel levels, sans air conditioners!

Consumer Guide recommends a Lennox as the quietest unit: ?Lennox
Signature HSX19-38 37,400 BTU Central Air-Conditioner Review
Air Conditioners
Rating:RECOMMENDED   Review: Lennox says its Signature HSX19
Collection includes the most quiet and efficient central
air-conditioners you can buy. It bases the claim on how the units
stack up against sound and efficiency ratings established by the
Air-Conditioning and Refrigeration ...

   ?The unit's noise output is 73 decibels. The next most-efficient
unit in the series (HSX19-36) has a SEER of up to 17.2, and its
decibel level is 70. An important aspect of the unit's
energy-efficient design, the company says, is a proprietary compressor
that runs at low speed up to 80 percent of the time. Vibration
isolators on the compressor, a new fan grill and cabinet, and a
special fan design are reportedly the keys to the quiet operation.?

Btu/hour cooling capacity
374000 Btu

According to Lennox, the Lennox, the XC21 is THE quietest central ac unit.

HSX15 is also touted to be THE quietist

The sound ratings of Lennox units

More Lennox Models

Lenox Models again

Tips on purchasing a central air conditioning unit

I hope this has helped you out! If any part of this answer is unclear,
please request an Answer Clarification and allow me to respond, before

Sincerely, Crabcakes

Search Terms
split level  air conditioners + sound LEVELS + decibel
central air conditioners + quietest + ratings
central air conditioners + reviews + quietest
central air conditioners + sound level ratings

Request for Answer Clarification by dodomixes-ga on 18 Jul 2006 22:04 PDT
Here is a quote from one of  the most useful articles you found. 

"It bases the claim on how the units stack up against sound and
efficiency ratings established by the Air-Conditioning and
Refrigeration Institute (ARI)."

I think this is the specific info I need. Are those sound ratings
available in a list that compares many manufacturers?

Clarification of Answer by crabcakes-ga on 19 Jul 2006 00:49 PDT
Hello again, Domomixes,

   I appreciate your clarification. I certainly searched for at least
one list of sound comparisons in my original answer, and yet again
tonight, all for naught. For some odd reason, links I followed that
appeared to have the data you want are broken! I searched extensively
and found no published data online, but many broken links, or pages
down. This is why in my original answer, I included data from
individual companies and AC reviews, rather than technical
For ARI Sound standards:

Sources: ASHRAE Publishes Unitary AC Standards
Air Conditioning, Heating, and Refrigeration News Online, April 19, 2002,1342,75890,00.html,1338,75886,00.html

   It appears that you can write to the ARI and obtain a copy.
The ratings are published by the Air-Conditioning and Refrigeration
Institute (ARI), 4301 North Fairfax Drive, Arlington, Virginia, 22203

   ?The Air-Conditioning and Refrigeration Institute (ARI) recently
announced the publication of ARI Standard 260-2001, Sound Rating of
Ducted Air Moving and Conditioning Equipment.

Standard 260-2001 establishes a method of rating the sound of the
indoor portions of ducted air-moving and conditioning equipment and
provides definitions, requirements for acquiring mapped sound data,
sound-power-level calculations and ratings, minimum data requirements
for published sound ratings, and conformance conditions. Standard
260-2001 is available for free download on ARI's Website
( Paper copies can be ordered by faxing a request to ARI
at 703-528-3816.? 

?This article reveals the understatement inherent in ?manufacturers provide
sound-power data.? It explains why meaningful equipment sound ratings
aren?t consistently available, and how a proposed industry standard,
ARI 260P, will help designers predict actual sound levels with greater

?Obtaining accurate, representative acoustical data for HVAC equipment
is an important step in any acoustical analysis. It also poses a
problem for system designers, particularly when the equipment includes
a fan. Here?s why:
_ Methods for predicting sound data vary from manufacturer to
manufacturer, hampering comparisons of equipment. _ Experience-based
?safety factors? applied by designers to offset potentially inaccurate
data often result in over-attenuation and unnecessarily inflate the
first cost of the system. _ The disparity between rating conditions
and the actual installation makes it difficult to design for proper

This document explains the standards, but does not rate brands



Operating Conditions for Standard Rating and Performance of Variable
Equipment Meeting the Requirements of Appendix A

Assessing the Impact of Air-Conditioning Outdoor Sound Levels in the
Residential Community

$20  Performance and Calibration of Reference Sound Sources

$20 Sound Rating of Ducted Air Moving and Conditioning Equipment

$30  Sound Rating Of Large Outdoor Refrigerating And Air-Conditioning Equipment

I hope this has provided you with a bit more information.

Sincerely, Crabcakes
dodomixes-ga rated this answer:5 out of 5 stars
The answer appears to exhaustive. Communication was pleasant and quick. Thanks.

There are no comments at this time.

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