Servicing variable-speed pumps for optimal performance

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Since 1990, HydroTher Hot Tubs have been the #1 choice of architects, consultants, designers and facility operators for commercial aquatic applications.

As planning for the 2023 pool season begins, it is a good time to brush up on the fundamentals. Pool professionals face a rapidly evolving industry, and this includes a shift in variable-speed pump (VSP) technology. By preparing for servicing variable-speed pumps now, service professionals can feel confident in tackling common challenges that may arise in the upcoming season.

Maintaining safety

Whenever there is a concern about equipment, worker and customer safety is top priority. First, a thorough inspection of the pool pump containment area and any exposed plumbing should be completed. Service professionals should always locate the main electrical circuit breaker panel to identify and confirm which breaker is designated for the pool pump before working on the equipment. A system should not be on when checking pipes or opening a pump, and the circuit breaker should be flipped so no power is going to the system before attempting any maintenance.

Optimizing flow

Single-speed pumps are less energy efficient than variable-speed pumps. When servicing a pool with the latter, the first thing to consider is the flow rate. Flow rate, or the volume of water passing through the pump, is a critical calculation step to determine the proper water turnover rate to maintain clarity and sanitary conditions. The flow rate should also be tested and adjusted regularly to maintain pool conditions.

Variable-speed pumps are designed to run at the lowest flow rate necessary to maintain peak performance while saving energy. While every pool is different, variable-speed pumps do not need to run at full speed or a high flow rate all the time to do their job effectively—in fact, it is often the opposite.

A pump must accomplish two primary goals, the circulation of chemicals and the skimming of debris. The pump can run at a low flow rate (or speed) for a lengthy period to circulate the chemicals and turn over the water throughout the day. While the low speed is effective at circulating chemicals efficiently, it would not do a sufficient job skimming the pool. As such, the pump will need to be programmed to run at a higher flow rate for short periods throughout the day to generate more surface water movement from the return jets and allow the skimmers to collect floating debris from the surface. Finding the optimal flow rate is both an art and a science and should be considered carefully when servicing a pool.

Tackling debris

If the pump’s speed and flow rate have been adjusted but a customer is still experiencing a lot of debris in their pool, the return jets should be checked. Return jets, sometimes called eyeballs, need to be arranged near the surface of the water to optimize circulation. Improved circulation at the surface allows leaves and debris to be skimmed before they sink.

Seasonally, especially around the end of summer into fall, pool owners start experiencing more leaves, seeds, acorns, and debris in their pools. This debris has the potential to fill a skimmer basket quickly. It is important to check the basket as often as possible for blockages as well. Blockages add friction to the pool system, and added friction means higher energy usage and costs. Keeping baskets empty allows pumps to work more efficiently to get the job done.

Watching for water leaks

Watching for and mitigating leaks is crucial to maintaining a variable-speed pump for years to come. Water leaks can be caused by a variety of factors, such as putting extra stress on a pipe when servicing the filter, accidentally leaning against a piece of plumbing, and even aged O-rings. In areas with changing temperatures, not draining the pipes effectively and subsequent freezing and thawing can also create leaks.

If a pump is experiencing a water leak, it is helpful to slow down or stop it to see if the leak can be traced to its origin. Often water leaks leave trace mineral trails which can be a helpful clue to follow. Another common source of a water leak is the pump’s mechanical seal; if it is worn out, a leak may appear in the middle of the pump and likely in front of the motor. However, if the mechanical seal is intact and the source of the leak cannot be determined, additional parts to investigate are the filter band clamp and the filter O-ring.

Resolving air leaks

An air leak is just as concerning as a water leak. Professionals may notice air in the strainer basket on the suction side of the pump. On single-speed pumps, the basket area would generally be full of water. Since variable-speed pumps run at lower speeds and flow rates, one may see air in the basket area, however, the air is not something to be alarmed by, nor is it a sign of a leak as it would have been with single-speed pumps. Air in the basket area generally means the amount of water going out of the pump and the amount of water coming in have reached an equilibrium.

So, how can one be sure there is an air leak? Running a quick-clean cycle is a good test. Quick-clean cycles run the pump at high speed. If, while the program is running, the strainer basket fills up with water, a professional can be confident the air was sucked out and there is no leak. However, when running at a high speed, air bubbles appear and the lid fills with air, it may indicate an air leak. Another simple way to test is by running a garden hose along the plumbing leading into the pump to see if it changes what is going on in the viewport.

Air leaks can be caused by a variety of factors. The ground shifting during changes in the seasons, fluctuating frost lines, or even ultraviolet (UV) rays that break down the components in the polyvinyl chloride (PVC) can all lead to an air leak. A cracked, stretched, or aged O-ring is also a common cause of an air leak and is often a relatively cheap fix. Replacing the O-ring, cleaning the groove it sits in, and applying a new coat of lubricant can often do the trick.

If the O-rings appear to be intact but an air leak remains, check the pump’s PVC plumbing. Over time and when exposed to the elements, the epoxy seal can become brittle and less effective. If an air leak stems from the plumbing, caulk can patch the crack, or the plumbing may need to be re-glued.

While leaks happen, steps can be taken to help avoid them. For example, protecting pumps from the heat by ensuring they are shaded from the sun and have ample ventilation. They should also always be protected from dirt and moisture.

Inspecting the impeller

The impeller is the heart of a pool pump and allows it to do its job effectively. An impeller is attached to the motor shaft and spins the water inside the pump. As the impeller spins, it energizes the water, increases the pressure, and makes the water move.

Keeping the pump strainer basket clean is critical to the performance of an impeller. If the basket is not cleaned properly and is full of fine debris such as sand, it can decrease the performance and even clog the impeller so it cannot start. In addition to checking the basket, service professionals should note any noises from the pump. A noise may indicate debris is stuck in the impeller.

Fortunately, modern variable speed technology, available with select pumps, allows professionals to gather feedback on the equipment in real-time via an app which helps professionals diagnose and fix problems more effectively. For instance, if a pump sends an alarm that the impeller cannot turn, the pump will have to be taken apart and examined
more closely.

While examining the pump, the mechanical seal between the impeller and the motor should be checked, as it can be a common source of water leaks. If leaking, water would likely show up as a puddle forming in the middle of the pump, just in front of the motor. While a mechanical seal typically has a life expectancy of a few years and may wear out, if it is still intact and the impeller is still not working, one can also check the clearance between the impeller and the diffuser for possible debris buildup in the tight channel.

Mitigating mechanical issues

The capacitor was a chief source of mechanical issues in single-speed pumps with induction motors. Now, however, variable-speed pumps are run with a drive on top as a mechanical inverter. While drives tend to be trickier to troubleshoot, there are things a professional should check for if experiencing a mechanical issue and an unresponsive drive.

If a drive is not working, always check the power first. If the power is on and the pump offers IoT (Internet of Things) connectivity, check to see if it is connected to the internet. Today, many pumps include technological advances that allow them to be controlled by an app, making remote monitoring possible and troubleshooting more streamlined.

While servicing a drive is notoriously complex, a pump that connects with an app allows a professional to diagnose a problem more easily. Select apps will alert a professional to alarm codes which can help them pinpoint the issue. If given an alarm code, a pool professional should reference the manufacturer’s website or the product manual to determine the appropriate next steps.

As the industry continues to evolve and products become more connected, professionals may be able to remotely receive alerts notifying them of issues with the equipment at their customers’ pools. This real-time monitoring can help service professionals proactively address problems before they escalate. Depending on the alarm code, they may even be able to bring a part with them that could fix the problem on the first trip—helping professionals accomplish tasks in just one visit, rather than several, further saving time and resources.

Operating optimally

Pool professionals must train the homeowner on the capabilities, functions, and maintenance needs of their variable-speed pump. While it can feel counterintuitive to some pool owners, operating the variable-speed pump at the slowest speed and flow rate possible to get the job done right is key to achieving clearer water. To ensure energy savings are actualized, the homeowner should understand that lower speeds and flow rates will provide adequate filtration for their pool.

By operating optimally, the temperature of the drive will decrease, allowing the electronic components of the pump to last longer. Additionally, operating a pump at the lowest speed and flow settings for the pool causes less mechanical wear to the machine.

By diligently maintaining variable-speed pumps, a pool professional can help mitigate common challenges before they arise. Not only can proper service and maintenance protect the longevity of the equipment, but it can also help save pool professionals and their customers time and money over time.

By Jimmy Miller

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