300 Level

301 - Chapter 1

What about Pump Electrical Consumptions

Operating costs are a consideration for everyone, now more than ever, so here are ways to keep costs down. First and foremost you’ll want to match your pump to the job. Always run pumps in their Best Efficiency Range. Knowing the flow you require in GPH and the Total Head of your feature, use the Comprehensive Pump Chart to find the pumps that deliver the performance you need in their Best Efficiency Range. That way you’ll get the most water pumped per watt and the greatest longevity possible out of your pump.


 Usually there’ll be a number of pumps on the Chart with the proper output near their Best Efficiency Point. We can predict which will cost least to operate by looking at how power consumption varies with the work a pump does. Very basically (and this is a generalization that may upset the real engineers out there!), the Laws of Affinity outline how modifying a pump’s impeller to increase volume squares the power required, while an increase in Head Height requires cubing the power needed. This is important enough to repeat. Twice the volume requires 22, or four times the power, while doubling the head height requires cubing -- 2x2x2 = eight times the power! In essence, this means that pumps with high head capacity cost exponentially more to run than low head, high volume pumps. To keep operating costs down, choose the lowest head pump that gives you the flow you want at the head height you need.

There is one more way to cut operating costs, but it’s not always possible with existing construction. It stands to reason that since it costs relatively more to pump to higher head heights, lowering the Total Head Height as much as possible will also lower costs. Now, you can’t lower the waterfall, but you can cut the friction head by eliminating restrictive plumbing, upsizing pipe diameters and eliminating fittings wherever possible. What happens if you can’t redo your plumbing? There’s one more trick to lower costs, regardless of the system – using two pumps instead of one in your water feature. Let’s talk about the Advantages of Redundancy.