In conclusion
There is much more to learn than can ever be summarized in a magazine article. To truly stay on top of the game, the Genesis 3 Advanced Fluid Engineering Design School is a valuable program. With a CD of more than 20 custom watershape-specific worksheets, plus 20 hours of detailed instruction, it is unlike anything ever offered in the industry. The schedule is available at www.genesis3.com. The class is limited to only 40 students, so sign up quickly (a laptop is required).
| AVOIDING COMMON PLUMBING MISTAKES |
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| One of the most common errors made among pool builders is undersized plumbing. A contractor once told me he sized the pool plumbing lines based on the horsepower of the pump. A 1.5-hp pump required 50-mm (1.5-in) plumbing; a 2-hp pump required a 63-mm (2-in.) plumbing; etc. Using our best practices approach, a 0.5-hp pool pump capable of flowing 340 lpm (90 gpm) at 9 m (30 ft) of head, would require 90-mm (3-in.) plumbing on the suction side of the pump. Historically, builders have also believed plumbing did not need to be any larger than the ports on the pumps. Some 0.5-hp pool pumps have 63-mm (2-in.) ports. For our 340-lpm (90-gpm) example, this would result in a line velocity of 2.6 m/sec (8.6 ft/sec)—exceeding the limits of several ANSI, NSPI, APSP and ASME standards. One might think 9 m (30 ft) of head is unrealistically low for this example. Keep in mind, however, that an unfiltered waterfall type feature is unlikely to have more than 9 m (30 ft) of total dynamic head if the plumbing is reasonably sized. The most important thing to note is that there is no relationship between pump horsepower and the size of the plumbing—the flow rate must be determined before sizing the pipe. |
David J. Peterson, P.E., SWD, is founder of Watershape Consulting Inc., a planning, design and engineering firm providing owners, architects, contractors and the legal profession with services relating to residential and commercial pools, spas and water features. Peterson is a registered civil engineer in multiple states, a member of the Society of Watershape Designers (SWD) and a Genesis 3 Platinum Member. He is also a member of the American Society of Civil Engineers, National Society of Professional Engineers, Construction Specifications Institute and American Concrete Institute.
