Troubleshooting – Unit
Symptom | Possible Cause | Corrective Action | |
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One or both |
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blowers turn off |
| Adjust frost temperature sensor set point as | |
intermittently and | Exhaust Only frost control sensors are tripping. | ||
needed. | |||
back on after |
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about 2 minutes |
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| Air seals are too tight. | See Energy Recovery Wheel under Unit | |
| section. | ||
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| “Economizer” sensors are operating. | Adjust temperature or enthalpy set points as | |
| needed. | ||
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Energy wheel does | No power to wheel motor. | Make sure wheel drive is plugged in. Verify | |
NOT turn | power is available. | ||
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| Wheel drive belt. | Check for loose or broken belts. Replace belts | |
| (consult factory). | ||
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| VFD overload. (OL1 on readout) | Refer to VFD section. Compare motor amp | |
| rating to setting in VFD. Adjust accordingly. | ||
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Energy wheel runs | Wheel motor overloads are tripping, due to | Recheck air seals, make sure they are not too | |
tight. See Energy Recovery Wheel under Unit | |||
intermittently | rubbing between wheel and air seals. | ||
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| Fan wheel rubbing on inlet. | Adjust wheel and/or inlet cone. Tighten wheel | |
| hub or bearing collars on shaft. | ||
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| Bearings. | Replace defective bearing(s). Lubricate | |
| bearings. Tighten collars and fasteners. | ||
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| Wheel out of balance. | Replace or rebalance. | |
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| Loose wheel on shaft. | Tighten wheel setscrew. | |
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| Loose motor or blower sheave. | Tighten sheave setscrew. | |
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| Belts too loose. | Adjust belt tension after 24 hours of operation. | |
Excessive noise |
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Belts too tight. | Loosen to maintain a 3/8 inch deflection per | ||
or vibration | |||
foot of span between sheaves. | |||
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| Worn belt. | Replace. | |
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| Motor base or blower loose. | Tighten mounting bolts. | |
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| Buildup of material on wheel. | Clean wheel and housing. | |
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| Bearing and drive misaligned. | Realign. | |
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| Make sure ductwork is supported properly. | |
| Noise being transmitted by duct. | Make sure ductwork metal thickness is sized for | |
| proper stiffness. Check duct size at discharge to | ||
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| ensure that air velocities are not too high. | |
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Always have a completed Pre
