You may have heard about the fantastic energy savings that can be realized with a variable speed pool pump (aka Variable Frequency Drive or VFD pumps). It’s true that these pumps can save a ton of money. Even running at the same flow rate, variable speed pumps are inherently more efficient than the single speed variety. When used at a lower flow rate over a longer period of time, a variable speed pump can save a huge amount of energy (although typically not the 90% that manufacturers lead you to believe). However, all variable speed pumps are not equal, and I’ll explain why.
The first thing to consider is the pump horsepower rating. The best residential pumps available today are rated at 2.5 HP (like the Hayward EcoStar) or 3.0 HP (like the Pentair Intelliflo). These pumps provide a huge range of options in terms of flow rate and pressure. Your pool’s existing plumbing may not be able to handle that kind of horsepower, but it is very nice to have a full range of flow rate options for features and heat sources. Some of the lower-end pumps, which may be good units, don’t cost much less and provide a smaller range of functionality. For the cost difference, I believe it makes sense to spend a small amount more to get the extra horsepower. The net result will be that you can run the higher rated pump at a lower speed, which results in longer life (in theory) and quieter operation. For one major brand you can increase your horsepower by 67% for just 15% more cost. Don’t get sucked into a great price for a 1.5 HP pump just because your existing single speed is only 1.5 HP (or less). That will partially defeat the purpose of a variable speed pump.
The next thing to consider is automation options, especially if you are going to have solar pool heating installed, or any automation system to control an electric or gas heater. The cheaper pumps offer either no external speed control options, or the options may be far too limited to be useful. When considering the more feature packed pumps (like the EcoStar or Intelliflo), you also need to consider the automation system that will be controlling them (existing, new, and future). The EcoStar is controllable with Hayward controllers or using analog inputs to control up to eight speeds. The IntelliFlo has a proprietary control cable to communicate with Pentair controllers for maximum options, but requires an interface unit to operate with most other automation systems. The Hayward and Pentair options end up with similar prices when considering the extra interface unit for the Pentair, but the Pentair wins on price, features, and horsepower if considered with a Pentair automation option.
More on Comparing Variable Speed Pumps
Even the top brands offer pumps that that are far more limited than their big brothers. The Hayward MaxFlo VS 1.5 HP pump has absolutely no external control options, and the logic for scheduled run times makes it unsuitable for applications where you want a desired speed based on the heat source. The Pentair Superflo VS 1.5 HP pump actually has nice automation options that are similar to the Hayward EcoStar and compatible with a wide array of automation systems, but does not have a digital interface that can operate without extra relays on Pentair brand controllers. And, both are rated at just 1.5 HP, which sounds great compared to existing 3/4 — 1.5 HP pumps, but you lose a lot of flexibility and noise savings because the smaller pumps run at a higher RPM to achieve the same flow rate.
Another option popular in Florida is the Jandy ePump 1.5 and 2.0 versions. These require a proprietary Jandy controller, even when used with external automation products other than and Aqualink system, and they cost substantially more for similarly rated pumps. The external control options are a bit clunky, but workable for heating applications.
Finally, there are “the rest.” There are a bunch of pumps available through various discount stores, and they generally offer little to no automation options, or have on-board controllers that limit the usefulness of the pump due to strange and rigid timer functionality (i.e. pump runs at speed 3 for two hours, them reverts to speed 1). Some pumps are passing themselves off as variable speed when they are actually two-speed pumps. Steer clear of these options.
So why does this all matter and what does it have to do with solar? Solar pool heaters (and other heat sources) require optimal flow rates to operate efficiently and effectively. Automation systems can “dial in” pump speeds to get optimal flow when a heat source is activated. When you use a pump that does not have sufficient automation options or flow capability, you are reducing the efficiency and effectiveness of the heat source. In many cases, heat sources will not work at all, or not work reliably when paired with an unsuitable variable speed pump.
So when considering a variable speed pool pump, don’t buy the wrong pump. Stick with the major brands and the top of the line. They cost only marginally more, and you get so much more for the money. You will also improve your flow rate options, minimize noise, and get far better automation options. Generally you want to match the brand to the automation if possible (but not always).
If you have questions about which Variable Speed Pool Pump to buy, or you are ready to move forward, contact Florida Solar Design Group!