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  1. #1

    IS A 3-Blade Condenser Fan Better than 2-Bladed?

    Folks,
    I've searched this fourm's FAQ's for this question and have not seen it covered. You'll might have, I just can't find it.

    I have a 2.5 ton 13-seer rheem that's a year old with a 2-bladed condenser fan. It's not real loud but the 2-blades seem to chop the air like a Huey cobra gun ship. Woop, Woop, Woop, etc. The units I've seen with 3-blades seem to have a smoother air draw. Is it possible to convert from 2 to 3 blades, keeping the same pitch and overall surface area the same. I would assume that that would keep the CFM flow the same. Any merit to this idea or am I just talking "Crazy Talk"?

    Thanks,

    Joe.

  2. #2
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,915
    More blades will make for smoother airflow, and better performance against higher static pressures, so would give better airflow as the condenser coil gets dirty.

    Typically Rheem/Ruud 2 blade fans only sound very choppy when the condenser coil is dirty. It is how I know one needs to be cleaned, before I even look at it.
    If more government is the answer, then it's a really stupid question.

  3. #3
    Join Date
    Feb 2004
    Location
    michigan
    Posts
    677
    Like Mark said, clean the condenser then decide if you need to change the blade.
    I am the "Wally". All others are meer imitations of the original.

  4. #4
    Join Date
    Nov 2008
    Posts
    1,673
    The AOP forums/Ask Our Pro's forums, are restricted to only Pro members that have been vetted by the AOPC can post advise, questions or commentary in a thread created by someone else. You need to apply for your vetting/* if you wish to participate in threads in the AOP forums. Please apply to the AOPC today, thank you.

    You can find the rules for posting and qualifications here.
    Last edited by beenthere; 08-21-2012 at 06:32 PM. Reason: Non Pro * Member

  5. #5
    Join Date
    Dec 2002
    Location
    Houston,Tx.
    Posts
    16,110
    You stick a 3 wing on the Rheem factory motor, and I can guarantee you the motor will overheat and shut down, been there done that. It either shuts down because of the weight or the changing of the factory design, don't know but it will shut down with the 1/5 hp motor. Most of the time what your hearing can be eliminated by lowering or raising the blade just a little, this noise is also caused by a dirty coil.
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  6. #6
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,443
    Is that a 13AJN30 by any chance? If so I can tell you why that POS is noisy!

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,556
    WhoIsThat?, this is the Ask Our Pro's forum, and restricted to only Pro members that have been vetted by the AOPC are allowed post advise, questions or commentary in a thread created by someone else.

    You can find the rules for posting and qualifications here.

    Your post has been deleted.
    Further infractions may result in loss of posting privileges.
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  8. #8
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,369
    Quote Originally Posted by Mr Bill View Post
    You stick a 3 wing on the Rheem factory motor, and I can guarantee you the motor will overheat and shut down, been there done that. It either shuts down because of the weight or the changing of the factory design, don't know but it will shut down with the 1/5 hp motor.
    Adding one more wing to the blade without increasing the horsepower of the motor will overload the motor every time. One more wing flying around is one more surface to move air (and its coinciding drag), so it requires more power to maintain the same RPM.
    • Electricity makes refrigeration happen.
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  9. #9
    Join Date
    Apr 2012
    Location
    winnipeg
    Posts
    1,330
    i concure
    it was working.... played with it.... now its broke.... whats the going hourly rate for HVAC repair

  10. #10
    Join Date
    Dec 2005
    Posts
    1,921
    Quote Originally Posted by joehaxby View Post
    Folks,
    I've searched this fourm's FAQ's for this question and have not seen it covered. You'll might have, I just can't find it.

    I have a 2.5 ton 13-seer rheem that's a year old with a 2-bladed condenser fan. It's not real loud but the 2-blades seem to chop the air like a Huey cobra gun ship. Woop, Woop, Woop, etc. The units I've seen with 3-blades seem to have a smoother air draw. Is it possible to convert from 2 to 3 blades, keeping the same pitch and overall surface area the same. I would assume that that would keep the CFM flow the same. Any merit to this idea or am I just talking "Crazy Talk"?

    Thanks,

    Joe.
    Yes, you can. BUT the new blade Must have less pitch. And the tech must be good to choose the right blade.
    Remember, the manufacture don't go "Ini mini miny mo" and got the blade.

  11. #11
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
    Posts
    6,051
    My 10seer rheem does have that faint helicopter sound.

    Does anyone know why rheem is partial to two prop?

    Look into a cobra blade from LAU. I think they make two props.

  12. #12
    Join Date
    Oct 2004
    Location
    So Cal
    Posts
    3,574
    Quote Originally Posted by SBKold View Post
    My 10seer rheem does have that faint helicopter sound.

    Does anyone know why rheem is partial to two prop?

    Look into a cobra blade from LAU. I think they make two props.
    They say they are quieter because of the 2 blades, but I've heard some pretty loud ones.
    Their outdoor fan motors seem to hold up well IMO- compared to other brands.

  13. #13
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    +1, it's possible to find a blade that will have the same load at the same motor RPM as your and at the same diameter... but it will take a good tech with a good reference manual and knowledge. Getting the same diameter is important. The location and clearance in refrence to the fan shroud is critical on any fan, centrifugal or axial.

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