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Alpha Mechanical Services Ltd.
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Vincent Geraghty - - 086 224 9988

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Commercial HVAC Pump Problems and Solutions

David Taylor

There are various types of pumps used in the HVAC systems, but the most common include the centrifugal pump and the booster pump. However, what happens when the HVAC pump cannot keep your building cool in the summer and warm in the winter? This means that you are having pump problems. Below is a list of the most commonHVAC pump problems and solutions.

Do you have a system of planned preventative maintenancePPM is a schedule of planned maintenance operations aimed at the prevention of breakdowns and failures. PPM ensures continuity of service, maximises efficiency and reduces total running costs.


1. Leaky Seals

The seal has an unpredictable lifespan, and it may fail for some reasons.The seal may fail because the seal faces open, excessive heat or the chemical environment. The seal should also not be allowed to run dry since this will cause damage to the seal and extreme leakage.Heat destroys seal faces and causes seal leakage.

Solution: You must ensure that the pump seal chamber is full of a lubricating liquid to prevent the seal from running dry. The seal needs to be replaced many times to keep it from wearing out. Routine maintenance of the seal is also crucial because the set screws may have gradually loosened.


2. Cavitation

Cavitation is the buildup of low-pressure bubbles in the liquid flowing through the system.If not addressed and corrected, pump cavitation may lead to severe problems. Cavitation causes damage to the impeller and reduces the life of the pump. Cavitation also leads to the accelerated wear and tear in seals and bearings.

Solution: Steps must be taken to increase the NPSH (Net Positive Suction Head) energy on the suction side of the HVAC pump. This can be done by reducing the temperature of the liquid being pumped, decreasing the number of elbows and valves, reducing the length of the pipe or increasing the pipe diameter.


3. Damaged Pump Shaft

The shaft may break due to instantaneous fracture that is caused by sudden imbalance or overload. This indicates that the shaft damage occurred suddenly rather than it occurring gradually. However, if the broken shaft is discoloured (blue), this means that excess heat was involved in damaging the shaft, and the damage occurred gradually.

Solution: Carefully check the belt drive system and the pulleys for any signs of fatigue. When installing belts, use a proper belt tension gauge. Also, check out for a damaged fan or fan clutch. The fan has to be correctly mounted on the pump shaft to prevent any damages.


4. Vibration And Out-Of-Balance Equipment

Excessive vibration indicates that there is a problem with the pump or the next pump system. The main causes of excessive pump vibrations may be mechanically induced, system induced or operation induced. The pump may vibrate due to bad bearings, unbalanced rotor, bent shaft, clogged impeller, or when you change from low to high suction energy pumps.

Solution: You have to check the pump for excessive wear, check the lubrication of bearings and replace the worn out bearings, avoid maximum size impellers, keep the flow in design range and maintain the speed in design range.


5. Oversized Pump

When the pump is oversized, it starts up and shuts down more than it should. This is because it only needs to run for a short period before it meets the thermostat requirement. On a typical day, an oversized pump will have more start-ups and shut-downs than a regular sized pump. This means that it will wear and tear sooner than expected.

Solution: The pump should be sized to run almost perfectly at the designed temperature. There is a lot more to look out for than just the square footage of the floor area when choosing a pump.


Rust, Corrosion And Deposit Build-Up

Corrosion and rust on the pump or the impeller may make the pump ineffective. Other deposits may also build up inside the pump causing it to clog and prevent it from functioning correctly. Corrosion and rust may be due to a spoilt pressure cap which may speed up the rusting process.

Solution: Check out the pressure cap and make sure that is functioning properly. You must also flush the pump to make sure that no deposits remain to clog the pump.