This Piece Of Crap Has NEVER Worked Right!!
If you have been in the refrigeration trade for more than a week you have probably heard this. If you own refrigeration equipment you may have said this. Read on to identify a likely culprit!
Look closely at the condenser and evaporator fan blades. All fan blades are “pitched” to move air. Most fan blades are “cupped” for aerodynamic efficiency (to move a larger volume of air). Stick your arm out your car window and form a cup with your hand. Cup facing forward you catch a lot of air, cup facing rearward your hand is more aerodynamic catching a lot less air. Same principle here. Fan blades installed backwards will look and sound normal but will move 30 to 50% less air depending on the aggressiveness of the cupping.
Condenser fan blades installed backwards will cause low air flow, high discharge temperatures, high discharge pressures, high compression ratio due to high discharge pressure, high compressor amperage draw, and premature compressor failure.Evaporator fan blades installed backwards will cause low evaporator air flow, loss of system efficiency, poor defrost on air defrost coils, compressor short cycling, high compression ratio due to lower suction pressure, and premature compressor failure.
In my years of service I have come across at least a hundred incorrectly installed fan blades. Many had been running that way for years, some from the factory, some since the fan motor was last replaced by an electrician or plant personnel who did not understand the aerodynamic feature of the cupped blade. It’s an easy mistake for a technician to make and equally difficult to detect unless you are looking for it.
To check for proper installation you will need to turn off the fan motor and allow the blade to come to a complete stop. Blades are cupped in the direction they move air. If the air is blowing in your face you should be looking down into the cup (concave). If the air blows away from you the blade should appear convex. On multiple fan units be sure to check each fan individually. Motor rotation must match fan blade rotation. There are those out there who are convinced that if they install a replacement motor with the opposite rotation you simply turn over the fan blade. Not the case. If your motor shaft rotates counterclockwise looking at the shaft, you must use a counterclockwise blade.
Isn't it amazing how a relatively simple concept can be so difficult to wrap your brain around when you throw in rotation!
If you have been in the refrigeration trade for more than a week you have probably heard this. If you own refrigeration equipment you may have said this. Read on to identify a likely culprit!
Look closely at the condenser and evaporator fan blades. All fan blades are “pitched” to move air. Most fan blades are “cupped” for aerodynamic efficiency (to move a larger volume of air). Stick your arm out your car window and form a cup with your hand. Cup facing forward you catch a lot of air, cup facing rearward your hand is more aerodynamic catching a lot less air. Same principle here. Fan blades installed backwards will look and sound normal but will move 30 to 50% less air depending on the aggressiveness of the cupping.
Condenser fan blades installed backwards will cause low air flow, high discharge temperatures, high discharge pressures, high compression ratio due to high discharge pressure, high compressor amperage draw, and premature compressor failure.Evaporator fan blades installed backwards will cause low evaporator air flow, loss of system efficiency, poor defrost on air defrost coils, compressor short cycling, high compression ratio due to lower suction pressure, and premature compressor failure.
In my years of service I have come across at least a hundred incorrectly installed fan blades. Many had been running that way for years, some from the factory, some since the fan motor was last replaced by an electrician or plant personnel who did not understand the aerodynamic feature of the cupped blade. It’s an easy mistake for a technician to make and equally difficult to detect unless you are looking for it.
To check for proper installation you will need to turn off the fan motor and allow the blade to come to a complete stop. Blades are cupped in the direction they move air. If the air is blowing in your face you should be looking down into the cup (concave). If the air blows away from you the blade should appear convex. On multiple fan units be sure to check each fan individually. Motor rotation must match fan blade rotation. There are those out there who are convinced that if they install a replacement motor with the opposite rotation you simply turn over the fan blade. Not the case. If your motor shaft rotates counterclockwise looking at the shaft, you must use a counterclockwise blade.
Isn't it amazing how a relatively simple concept can be so difficult to wrap your brain around when you throw in rotation!
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