Common Boiler Feedwater Pump Faults and Solutions

Common Boiler Feedwater Pump Faults and Solutions

Steam boilers produce steam by boiling the water inside them. They continuously need feedwater to replace the water that is lost. The devices used to replace the water lost from steam boilers are called feedwater pumps. Boiler feedwater pumps must have sufficient pressure to overcome the boiler's steam pressure and sufficient capacity to meet the required water flow rate.

Many faults can be encountered when using a boiler feedwater pump.

Do you know what the common faults of feedwater pumps are? Why do feed pumps stop running as efficiently as they did on day one? What methods should be used to solve these problems? Below, we explain the common faults encountered in boiler feedwater pumps and their solutions.

Having trouble because your pump is underperforming or not running at all? Before starting to look for a solution, we need to understand exactly what symptoms will help with boiler feed pump repair. You can start your investigation by finding answers to the questions below; the answers to these questions will make your troubleshooting easier.

First, check whether enough water is reaching the pump from the condensate tank. Boiler rooms rarely operate in an ideal environment; contaminants or other environmental factors often affect pump operation. For example, in a textile factory, thread fibers may somehow have entered the condensate tank and blocked the pump filter.

If you don't yet have an idea what's causing your water pump failure or poor performance, vibration can be both a cause and a symptom of many feedwater pump problems; so watch for humming, rubbing or similar straining sounds that differ from normal operation. These sounds may indicate, for example, that the gasket or seal has worn and lost its properties. Left unaddressed, this can easily lead to further damage. Similarly, you may feel excessive heat from certain parts of the equipment caused by unwanted friction or vibration.

Conducting a broad investigation will help you pinpoint the exact signs of the problem. If the pump motor isn't running, this could be because a fuse has blown, a thermal overload has tripped, or one of the electrical phases feeding the motor is missing.

Businesses order a steam boiler rated to operate at 10 bar, but then run it at a lower pressure (for example, 5 bar). Because the feedwater pump is selected to match the 10-bar boiler, cavitation occurs in pumps operated this way. Cavitation is a pump's worst enemy; a pump should not be operated this way.

1. First, check the condensate tank water level. Running the feed pump dry causes damage.
2. Remember that the condensate tank's position must be higher than the feed pump's water inlet. Check that sufficient water is comfortably reaching the feedwater pump. Check that there is no blockage in the suction pipe between the condensate tank and the pump filter, and that no foreign material was left in the pipe during installation.
3. If the steam boiler feedwater pump doesn't run at all, first check its fuse. If the fuse has blown, investigate why; make sure all phases are reaching the feed pump. Have this kind of electrical work done by an experienced electrician.
4. Check the rotation direction of the feed pump's electric motor. If the pump rotates in reverse, it cannot pump water. Check the pump's electrical connection to confirm the rotation direction.
5. Check that the pump filter (strainer) isn't blocked. Also check that the valves on the suction and discharge lines are open and in good condition. Valve handles parallel to the pipeline indicate the valve is open; on handwheel-type valves, the valve opens by turning left.
6. Check valves can leak backward. Clean any foreign material found in check valves; replace worn check valves with new ones.
7. If the feedwater pump is running but the steam boiler's water level isn't rising, the pump may be air-locked; the pump needs to be bled of air.
8. In cold weather, the water inside the pump can freeze. The pump impellers freeze and jam, the electric motor is strained, and eventually the motor's fuse blows; if the fuse setting is changed and the pump is forced to run, the electric motor will burn out. In cold weather, pumps must be protected from freezing. If the water inside the pump freezes, the pump body can crack and become unusable. If the boiler isn't running, the water inside the boiler and pump should be drained. On first startup, warm water should be used to fill the pump through its air-vent tap.
9. If flow rate is lower than expected, the feedwater pump may be blocked, or the seal may be badly worn.
10. If the pump is drawing too much power, the seal collar may be too tight, or the impeller may be worn. Make turning the pump easier by slowly rotating it from the electric motor's shaft nut.
11. If there is an abnormal sound while the water pump is running, investigate the source of the sound; the pump impellers may be worn. If the pump shaft and motor shaft are not aligned on the same centerline, the pump and motor shaft centerlines need to be aligned. Get help from a pump service provider.
12. If the feed pump has overheated, investigate the cause of the overheating. Using excessively hot condensate water can cause the pump to cavitate, and cavitation wears down the pump impellers. In this case, the condensate water should be cooled. Also consider that the underlying problem may stem from faulty steam traps; have your business's steam traps and piping checked. Pump impellers that constantly handle boiling water wear out faster than normal, and the pump can no longer deliver the required flow rate.
13. If your pump can no longer achieve its original efficiency, its seal or impellers may be worn; pump components are, by nature, manufactured from wear parts. Having your pump serviced and inspected, and carrying out the necessary repairs, can restore it to its original efficiency.