Combustion Air Fan & Efficiency

In order for your boiler to operate at peak efficiency, it is important that the correct balance of fuel and combustion air is achieved. Air and fuel ratios are controlled through linkages, fans, dampers and the increase or decrease of gas pressure. Gas pressure is controlled through a pressure regulator and a fan controls the volume of combustion air.
If there are any problems with the fan, more energy may be introduced into the system, causing decreased efficiency. To help ensure that your equipment is running at its peak performance, please review the common fan problems below.

Fan Capacity/Pressure is Below Rating:

1. Dampers or variable inlet vanes are not adjusted properly


2. Fan inlet or outlet conditions are impaired


3. Multiple air leaks within the system


4. Damage sustained to the blower wheel


5. Direction of rotation is incorrect

Fan Vibration:

1. Worn bearings


2. Unstable foundation


3. Foreign material in the fan causing an imbalance


4. Misalignment of bearings, couplings, wheel or v-belt drive


5. Damaged wheel or motor


6. Bent shaft


7. Worn coupling


8. Loose dampers or variable inlet vanes


9. Speed too high or incorrect fan rotation


10. Vibration to fan transmitted from another source


11. Uneven blade wear


12. Loose or broken bolts or set screws

Overheated Bearings:

1. Improper lubrication


2. Poor alignment


3. Damaged wheel or driver


4. Bent shaft


5. Abnormal end thrust


6. Dirt in bearings


7. Improper belt tension

Overload on Driver:

1. Speed too high


2. Direction of rotation is incorrect


3. Bent shaft


4. Poor alignment


5. Improper lubrication


6. Wheel wedging or binding on fan housing