It is important for today’s open cell cooling towers to be aligned with their corresponding pumps at a reasonable vertical distance above the center line of the pump. The proper operation and vertical distance of the pump relate directly to the prevention of cavitation. Cooling towers should be at a higher elevation than the pump so that when water gets into the pump, the pressure is significant enough to prevent the water from vaporizing, which causes cavitation.

In recent years, cooling towers have been placed at the same elevation as the pumps, but the resulting cavitation has forced companies like Taco Comfort Solutions to find better ways to address those challenges.

In the past, cooling towers were almost exclusively on the top of buildings. It was rare to find a cooling tower on the ground. However, in recent years, placing the towers on the ground has become common and has caused a series of problems—most importantly, a limited amount of pressure to keep the pump from cavitating.

There are a few common solutions:

1. Raise the cooling tower, which is expensive because a structure to support the tower must be built that is supportive and aesthetically pleasing (generally a screen wall around the tower).
2. When trying to increase vertical distance, the pump can be placed low in a concrete pit—almost like a vault.
3. An alternative to the above solutions is to use a vertical turbine pump. The elevation change is at the bottom of the vertical shaft of the pump. The length of the vertical shafts can be controlled. With an average vertical distance of between 10 and 20 feet, by extending the vertical turbine column below the water level and the cooling tower, the vertical distance can be effectively
   increased without actually raising anything, or lowering the pump, or building any additional expensive structures.

The available pressure must be greater than the required pressure. Raising the towers to accomplish this is expensive. Lowering the pump into a concrete vault is not an easy task. With the vertical turbine pump, the vertical distance is easily raised without taking the distance from the inlet of the pump. With the suction at the bottom of the can, the length can be adjusted appropriately. If more pressure is required, the length of the can, and ultimately the length of the pump, can be made longer.

Cooling towers placed on the ground lose their vertical distance which decreases the available pressure. The vertical distance is now measured not from the suction of the pump but from the bottom of the can. The vertical turbine is used as a condenser water pump in this application and solves the problem with respect to how high the cooling tower may have to be in order to create enough pressure for the pump to work properly.

This solution can also be retrofitted into existing applications depending on the amount of physical space available. If there is horizontal space between the cooling tower and the building, a hole can be easily drilled in the ground, a concrete pad added, and then a canned pump mounted inside the opening. When properly selected, the performance and efficiency of the vertical turbine pump can be equal to or greater than a conventional pump—creating an elegant solution.

Using vertical turbines as a solution to conventional cooling towers has become common for larger facilities like district heating and cooling and universities. It also works as a solution for mid-sized office buildings around 200,000 square feet with a cooling load of about 500 tons (1,000 gpm).

There is a premium to pay for a vertical turbine can pump in this application, but the cost is offset by the savings on structure and screening, and most importantly, minimizing the possibility of cavitation—which happens when there is not enough pressure at the inlet of the pump.

For more information about vertical turbine pumps and solutions from Taco, please follow this link: https://www.tacocomfort.com