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What role does the pumping system play?

The sizing of a swimming pool pump (1 hp., 11/2 hp, 2 hp, 2-speed, varible speed and so on) should have a corresponding relationship with the skimmers, main drains, return lines, equipment selection and other key components of the swimming pool.

Skimmers and Main Drains are plumbed into the suction side of a pump. The suction side of the pump draws water from the pool by reducing the atmospheric pressure (14.7 P.S.I. @ sea level) inside the piping system (atmospheric pressure is the weight of earths atmosphere on the globe). This process is attempting to create a vacuum by lowering the earth’s atmospheric pressure inside the piping system and causing the water inside the pipe to become drawn to the void of atmospheric pressure created by the pump’s impeller.

The objective is to lower the atmospheric pressure in order to draw the water to the pump head but, not actually create a complete vacuum. If, the restrictions in the plumbing system are to great it will cause excessive “friction losses” creating a vacuum and this can result in a destructive condition called “cavitation”.

QUESTIONS TO ASK

• What is the negative suction lift requirement for my pool?
• What are the total friction losses through the entire filtering system, suction to return?
• What is the Total Dynamic Head (TDH) of the entire system?
• What is the electrical efficiency percentage rating of my pump at the designed flow rates?

Note: If you don’t get a straight answer from your pool builder on these questions, you probably won’t like your future electric bills.

How does more cost less?

In calculating the requirements for a swimming pool’s pumping system several elements must be considered. The quantities of these “inlet” devices in combination with piping distances and piping sizes all have a restrictive value on the movement of a given desired quantity of water and this is referred to as the “negative suction lift requirement (NSL)”.

Essentially the impeller is designed to draw water from the inlet side and then push water out of the outlet side. The more efficient this is done according to the pump’s impeller design the less electricity is used during the pumping process.

QUESTIONS TO ASK

• What horsepower rating is my pump and why has that size been selected?
• What is the “Service Factor” of the pump selected?
• How many hours per day will I need to operate my filtering system?
• What is the Kilowatt electrical consumption and designed water flow rate of my pumping system?
• What will my pool cost to operate, monthly, yearly and over it’s lifetime?

Note: If your pool builder can’t answer these questions upon presenting a design a crucial component of the design is missing.