Troubleshooting – Unit
Symptom | Possible Cause | Corrective Action | |
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| Blown fuse or open circuit breaker. | Replace fuse or reset circuit breaker and check | |
| amps. | ||
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| Defective motor or capacitor. | Replace. | |
Blower fails to |
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Motor starter overloaded. | Reset starter and check amps. | ||
operate |
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Electrical. | Check for On/Off switches. Check for correct | ||
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| supply voltage. | ||
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| Drive. | Check for broken or loose belts. Tighten loose | |
| pulleys. | ||
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| Control power (24 VAC) wiring run is too long | Shorten wiring run to mechanical room or | |
| install a relay which will turn unit on/off. Consult | ||
Motor starters | (resistance should not exceed 0.75 ohms). | ||
Factory for relay information. | |||
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“chatter” or |
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Incoming supply power is less than anticipated. | Need to increase supply power or use a special | ||
do not pull in | |||
| Voltage supplied to starter coil must be within | control transformer which is sized for the actual | |
| +10% / | supply power. | |
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| CFM too high. | Check cfm and adjust drives if needed. | |
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| Static pressures are higher or lower than | If higher, ductwork should be improved. | |
| design. | If lower, fan rpm should be lower. | |
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| Blower rotation is incorrect. | Check rotation and reverse if necessary. | |
Motor over amps |
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Motor voltage incorrect. | Check motor nameplate versus supplied | ||
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| voltage. | ||
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| Motor horsepower too low. | See specifications and catalog for fan curves to | |
| determine if horsepower is sufficient. | ||
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| Shorted windings in motor. | Replace motor. | |
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| Unit damper not fully open. | Adjust damper linkage or replace damper motor. | |
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| System static pressure too high. | Improve ductwork to eliminate losses using | |
| good duct practices. | ||
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| Blower speed too low. | Check for correct drives and rpm with catalog | |
| data. | ||
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| Fan wheels are operating backwards. | For | |
Low airflow (cfm) | Rotation under Unit | ||
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| Dirty filter. | Follow cleaning procedures in Routine | |
| Maintenance section. | ||
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| Leaks in ductwork. | Repair. | |
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| Elbows or other obstructions may be | Correct or improve ductwork. | |
| obstructing fan outlet. | ||
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| Belt slippage. | Adjust belt tension. | |
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| Blower fan speed too high. | Check for correct fan rpm. Decrease fan speed | |
| if necessary. | ||
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High airflow (cfm) | Filter(s) not in place. | Install filters. | |
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| Insufficient static pressure (Ps) (airflow | Induce Ps into system ductwork. Make sure | |
| grilles and access doors are installed. Decrease | ||
| resistance). | ||
| fan speed if necessary. | ||
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Always have a completed Pre
Model PVe Heat Recovery Unit 27