We’ve covered how pumps work. Now let’s tackle the different types of pumps available on the market. We will not get into specific horsepower, but will use Hayward models as examples and cover how pumps perform depending on their design.
There are three basic types of single speed pumps (variable speed pumps will be covered in a later article); low head, medium head and high performance. Back in the old days, the bronze pump was the standard. Most manufacturers did not market the pump types as this was the primary pump used. As composite material became available, and close face impellers came to the forefront, we saw the changing face of pump types.
Low-head pumps are designed for high flow, at low head pressures. Normally these pumps are used for waterfalls or water features where there is little or no back pressure (no filter, heater or other restrictions to flow). When we say low head pressure, this means the pump will not operate properly above 20-25 feet of head. These pumps require large pipes and are perfect when water doesn’t need to be pumped higher than 10 feet. Hayward offers two low-head pumps – the TriStar Waterfall Pump, 75 and 120GPM. Also,
these pumps normally run at 1725RPM (normal RPM, or Revolutions per Minute, is 3450) and have a large impeller.
Medium-head pumps are the work horses of the pool business. They are designed to provide water circulation up to approximately 80 feet of head pressure. They are very forgiving pumps – as it is hard to cavitate a medium head pump. On pool-only applications (no spa or water features) medium-head pumps are king. Hayward has two medium-head pumps, the Super Pump® and the Max-Flo XL™ line of pumps. When you only need to circulate the water, medium-head pump are usually the right choice for 1.5 & 2” plumbing.
High performance pumps became necessary as pool designs became more complex. The addition of spas and water features put demands on pumps that they couldn’t handle and forever changed the market. Newer popular applications with spas, slides and other water features, require pumps that can overcome higher head pressures and higher restriction to flow to provide the water necessary for proper operation. Hayward makes the Super II™ and TriStar® High Performance pumps.
As pumps evolved over the years, many hydraulic problems came to light. The most common issue is when the wrong pump type is used for the application and improper pipe sizing. We often hear of high-performance pumps being used improperly in medium and low-head applications. When a high-performance pump is used on a low-head application, (such as with a waterfall with little back pressure) the pump will be very noisy as it usually requires some back pressure for quiet operation. Other problems arise when
piping is improperly sized. This first came to light when spas were added to pools and we wanted one pump to do the job for both. If you have a pool needing 50GPM for circulation and add a spa needing 90GPM for the jets, the one pump needs to be sized for the spa needs. What is being ignored is that the plumbing throughout the pool needs to be sized larger to accommodate the flow.
Join us next time as we talk about the newest addition to the pump types, variable
speed. We look forward to you jumping into the conversation. Get involved, stay connected!