Swimming pool pumps
What is a swimming pool pump?
Swimming pool products like pool pumps are mechanical devices that work in conjunction with the swimming pool filters to maintain your pool's cleanliness. A swimming pool pump works by extracting water from the swimming pool and pushing it through a filter to trap debris and dirt. The swimming pool pump then sends the clean water back into the pool. Some swimming pool pumps are fitted with a straining basket to catch debris, many with transparent lids to allow you to monitor the basket. Swimming pool pumps generally have one or two speeds and different levels of power. Swimming pool pumps are offered in a large selection with many different sizes and pumping capabilities. They are available for smaller above ground pools whilst more powerful designs are available and better suited to inground pools. Above ground pool pumps tend to be less expensive than inground pool models.
How does it work?
Most swimming pool pumps are classified as self-priming centrifugal pumps. That is, the centrifugal force that is created by spinning the water, will force the water downwards and if there is an opening or a hole, this water will get pushed forward through the hole. The swimming pool pump operates the same way. Swimming pool pumps require a vacuum chamber, known as the swimming pool pump housing, which must be filled with water so that the swimming pool pump can make a vacuum and enable it to pull water from your pool. The swimming pool pump housing will remain full (of water) whilst it is switched on, and remain full or mostly full during its inactive time. When a swimming pool pump is switched on its motor rotates, driving the impeller, found in the swimming pool pump’s center section at the opposite end from the electrical switch part of the motor. During the motor’s action, the tips of the impeller are sealed hydraulically inside of the swimming pool pump diffuser. This enables what is known as self-priming to occur. Swimming pool pumps used for pools are self-priming, that is, they expel the air inside upon start-up, creating a vacuum that starts suction. Once water is flowing through the swimming pool pump, if you close a valve on the outflow side of the pump, restricting all flow, maximum possible pressure is created. However, there is no destructive force created, the impeller simply spins in the liquid indefinitely.
What size of swimming pool pump do I need?
Every swimming pool pump has a capacity that lets you know how much water it can circulate. When buying swimming pool products like pool pumps it is important to look at their circulation ability and see how much they can pump either by the minute or by the hour. A good basic rule of thumb is to ensure that the swimming pool pump can circulate your pool’s entire water volume in around 8 hours (three times a day). It is important also to check the energy efficiency of the swimming pool pump as well as the warranty conditions to ensure you get the optimum power for your money. Most existing swimming pool pumps are oversized for the size of the pool and plumbing, which reduces swimming pool filter effectiveness and causes more wear and tear on plumbing. Many swimming pool owners have bigger pumps, which dramatically increases electrical pumping costs. The running water not only encounters friction created by swimming pool pipes and swimming pool equipment, but the water itself is creating friction. This friction will strip copper from pipes and swimming pool heater components causing all kinds of havoc, damages swimming pool filter grids, and makes DE or sand inefficient (also see the topic Swimming pool filters). Because of this, most building codes set maximum flow rates of 2,44 meters per second through copper pipe and 3 meters per second through PVC. Since swimming pool heaters all use copper heat exchangers, use 2,44 meters per second even if the plumbing is PVC. But what is meters per second in terms of liters per minute:
- 190 lpm in 38mm pipe = 2,4 meters per second
- 190 lpm in 50mm pipe = 1,46 meters per second
- 228 lpm in 38mm pipe = 2,9 meters per second
- 228 lpm in 50mm pipe = 1,74 meters per second
By the way, there are a few exceptions to the rules. When sizing swimming pool pumps, you must assume at least 18 meters of head regardless of the actual calculations. In swimming pool filters, on the other hand, you must use the actual head as measured. Altitude also affects these calculations. Over 1000 meters above sea level a motor runs hotter, so you will want to upgrade to the next horsepower. It is also worth noting that certain swimming pool pumps work better with different swimming pool filter types.
What role play swimming pool pump filter and swimming pool heater?
The size of your swimming pool filter is another factor to consider when sizing the swimming pool pump. If the swimming pool pump is too large for the swimming pool filter, it can make the swimming pool filter work poorly or even worse and it can damage the swimming pool filter internals. Generally speaking, the slower the water moves through the swimming pool filter the better the quality of filtration, particularly with sand or DE filters. If the water flow through the swimming pool filter is not strong enough, for example there is an accumulation of debris or dirt in the swimming pool water filter, the swimming pool heater cannot get enough water flow and the swimming pool heater will stop. But the problem with that is the fact that the swimming pool heater needs a higher water flow also to get started. For swimming pool heaters a minimum water flow rate of 5000 l/min is recommended. Chlorine generators, gas-fired swimming pool heaters, heat pumps, solar systems all require certain gallon per minute rates and each have different levels of restriction or head loss for those flow rates. When designing a complex pool project it is advisable to have manufacturers' flow and pressure drop tables to insure balanced flow for elements of the pool. So it is important to find swimming pool products (swimming pool pump, swimming pool filter and a swimming pool heater) that are compatible in this matter. The Euro Pool Shop will consult you in every thinkable way, to help you finding the appropriate swimming pool equipment.
