Spring weather has been a rollercoaster ride, with highs close to 80 F some days, followed by nighttime lows in the 30s the next day. Fans have started to hum to life under these conditions, but some may not have started or are making strange noises.
Cows can hear high-pitched fan noises we can’t, and move away from fans that need repair. When the fans did turn on, they were probably running less efficiently than they should have due to dirt buildup.
Fan maintenance is critical to keeping your cows cool and saving energy. Lack of cleaning can reduce a fan’s efficiency by as much as 40%, meaning that your electric bill stays the same, but less air is moving through the barn.
Maintenance
Monthly maintenance through the summer is critical to keep fans clean. Even a thin layer of dirt on the fan blades, shutters and protective shrouds reduces airflow and increases the fan’s power requirements. A pressure washer can effectively remove dirt from the fans.
Be sure to disconnect the power supply before washing the fan, and be extra cautious of water entering unsealed motors. After washing, allow fans to dry and grease the bearings before turning the power back on.
During washing, inspect the fans closely using the following maintenance checklist: Do all shafts turn smooth? Are bearings showing wear (try to wiggle them in the bearing housing)? Are there cracks on the impeller? Are belts worn? Are pulleys still aligned and fit the belt V properly?
Helpful tools
While monitoring fan performance, wear can be challenging: here are a few tools that can help. Fans should be monitored on a routine basis, such as monthly during the summer or at the manufacturer’s recommended grease interval.
Logbook
If you assign a number to each fan on the farm, it will help track the maintenance costs of each fan. The logbook allows you to monitor when a fan shows increased belt wear or when motors are not lasting as long as they should, which are signs of more serious problems. Recording air velocity also helps to notice wear issues before they become major problems.
Thermal imaging camera or infrared temperature gun
These tools are used to evaluate the operating temperature of motors and bearings while equipment is running. As bearing wear increases, friction and heat rise, which can be a fire hazard. Monthly checking and recording of bearing, motor and belt temperatures can improve ventilation and help prevent fire.
Digital Anemometer
This is used to measure the air velocity to determine if fans are operating properly. Be sure to record these values in your logbook so you can identify changes in fan performance. Lower air velocity is often caused by either dirt buildup or improper belt tension, allowing for slippage. Ideal wind speed at cow height in the barn is 2.5-5 mph.
Digital Tachometer
This is used to help determine why your fan may not be producing enough air velocity, as well as the RPM of both your fan and the motor. When the motor is running at the correct RPM, but the blades are not, it may be due to poor belt tension, damaged or worn pulleys.
Groove Gage
This is used to identify pulleys that are worn and need to be replaced. Worn pulleys increase belt wear and slippage and decrease fan RPM’s. Belts should ride at the top of a pulley and not sunken into the pulley. The gage should fit tightly; if more than 1/32 inch of wear is visible, poor belt life can be expected. If the gauge hits the bottom of the pulley, it is worn out.
Belt Tension Tester
This is used to measure the force required to move a belt 1/64 inch per inch of span, and helps troubleshoot fans that are turning slower than they should. If the tension is correct but the fans are turning too slowly, the pulleys or belts may be worn out. If belts with spring tensioners cannot be tensioned correctly, it may indicate that the spring tensioners are weak or that the belts are stretched or improperly sized.
Multi-Meter
This allows you to check the fan motor’s amp draw; high amp draw can waste electricity and lead to premature motor failure. This can be caused by too high a belt tension, dirt buildup on blades and housing or bearings that are binding and need to be replaced.
When replacing motors, it is important to consider more than just the price. Many motors have electric efficiency ratings; higher-efficiency motors have more copper windings, which increases their cost. High-efficiency motors usually pay for themselves by reducing electricity consumption within one to three years.
