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

[joehaxby]

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.

[mark beiser]

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.

[wally01]

Like Mark said, clean the condenser then decide if you need to change the blade.

[WhoIsThat?]

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[Mr Bill]

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.

[BaldLoonie]

Is that a 13AJN30 by any chance? If so I can tell you why that POS is noisy!

[beenthere]

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[Shophound]

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.

[carmon]

i concure

[just_opinion]

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.

[SBKold]

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.

[precision hvac]

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.

[motoguy128]

+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.