Pool Circulation Equipment
Basic Pool Pump Primer
Having to purchase a new pool pump can often be a frustrating and expensive process. Oftentimes, pool builders steer customers towards pumps larger than needed for their pool. Over time, any pump that is too large for the plumbing and equipment can not only cause damage to the filter and other components, but it will use more energy than a smaller pump. It will also not deliver that much more performance, if any, for the extra cost in energy.
As an example, a 2 HP pump will produce only 15% more flow than a 1 HP pump (assuming proper pipe diameters), and will consume twice the energy for a given plumbing system. That is considerably more to pay every month, while not getting much in return. That said, with a little bit of knowledge of pumps and plumbing, the pool owner has the tools necessary to choose what is best for their own pool.
Pool pumps are available in two ratings; full rated and up rated. Up rated pumps are sometimes called max rated. The only real difference of these pumps is how the pump is labeled in terms of horse power (HP). Manufactures sometimes sell identical pumps in full rated and up rated versions. The difference being that the full rated version will have a lower HP but a larger service factor (SF), while the up rated version will have a higher HP but a lower SF.
Service factors determine how far over the rated or labeled HP the electric motor can be “pushed”. Most all pool pumps today are used at close to full load, which is sometimes called braking HP. This is also called service factor HP, or operating HP, and it can be calculated by multiplying the labeled HP by the service factor. A full rated 1 HP pump with a service factor of 1.5 would have a braking HP of 1.5, and would be identical to an up rated 1.5 HP pump with a service factor of 1 HP. Both pumps will have the same pumping capability and will provide the same flow rates for a given plumbing system. This is one of the most confusing aspects when considering pump ratings.
In addition to pump ratings, pumps can also be purchased as single speed, two speed and variable speed. The option of having additional speeds has advantages for pools with multiple flow rate requirements. Some examples of where you could use higher speeds would be for spa jets, water features, better skimming, or pool cleaners, while lower speeds are useful for general filtering and circulation.
The obvious benefit of multi-speed pumps is that they cost much less to run at lower speeds than at higher speeds. A simple two speed pump will use approximately 1/3 of the energy on low speed versus running at high speed. Keep in mind though, to get the same filtering of the water, the pump needs to be run twice as long on low versus high. This will still produce savings over 33% in energy. Variable speed pumps will have even more savings on lower speeds.
While a single multi-speed pump can (and is) often be used for pool filtering, spa jets and/or waterfalls, it is not always the best option. When you only have one pump, there is usually not enough flow to operate multiple features at the same time, an something will suffer. Additionally, sending high flow rates through the filter will reduce the life of the filter and reduce its filtering efficiency. To get the best performance for spa jets, waterfalls and other high flow water features, it is best to dedicate a high HP pump to each individual function. With a separate pump for the spa jets, spa filtering and heating can still be accomplished with the pool filter pump and appropriate valve plumbing.
Spa jets require much higher pump HP requirements than pool filtering, and usually require at least 15 GPM per jet. For spas with a large number of jets (more than eight), it may not be possible to get a pump with a high enough HP, so using multiple pumps separated into jet zones is common.
For circulation and filtering, larger pools will require larger HP pumps than smaller pools. However, most residential pools generally do not require more than a 3/4 HP pump for proper filtering. There are many pump manufacturers out there (Pentair, StaRite, Hayward and Hybrid, to name a few). One is right for you!