If you’re new to the well pump business, there’s a lot of new terminology to get used to. Gallons per Minute (GPM), Total Dynamic Head (TDH) and the like are pretty unique terms. But Horsepower sounds pretty simple at first glance, there’s just more power as you increase it, right?
At its core HP is a measurement of raw power (i.e how quickly ‘work’ gets done). In the U.S., 1 HP is equivalent to about 746 Watts, which is a common measurement of electrical power specifically. So it makes sense that as you increase the running power of your well pump, you’ll increase the values the pump outputs (namely GPM and TDH). GPM is a measurement of liquid velocity (in this case how fast water flows), and TDH is a measurement of how much pressure that water is under (and subsequently how high it can flow against gravity). Depending on how a submersible well pump is built, increasing HP can increase GPM, TDH, or both!
When looking at our 1 HP pumps, you can notice that we recommend them for a max TDH of 500’, and max GPM of 62. Our 1.5 HP pumps have both higher max TDH and GPM. Of course, these aren’t the same pumps, but rather their construction is geared towards one or the other metric output. As a general rule, high head pumps are slightly longer than high GPM pumps, but the key thing to understand is that increasing your HP does not necessarily increase TDH or GPM. You need to analyze the pump curves for the pumps you’re interested in.
Image 1: Pump Curves of our 05RPS Series
With our 05RPS series, for example, you can see that our 1HP 5RPS10 and 1.5HP 5RPS15 are fairly close to each other, relatively speaking. The max head difference is about 200’, and max GPM cuts out at 8 for both pumps. Let’s say you need a pump doing at least 5 GPM at 400’ of lift, then you’re right on the money with the 1HP. But if you need higher GPM at the same amount of lift, or vice-versa, you’d need to size up.
Image 2: Pump Curves of our 25RPS Series
