In layman's terms, can someone explain to me what the difference is and in what application is each of these best used for?
High flow vs High pressure pumps
- Thread starter Pcmaker
- Start date
- May 23, 2015
- 24,651
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Pool pumps are generally "high head" or high pressure pumps as they can push water up a higher distance. This allows them to overcome the dynamic and static head loss (resistance to the flow of water) of your entire plumbing system so that water can flow through it and a given pressure range and flow rate.
Waterfall pumps (low head or low pressure), or pumps that supply a water feature with an open end (sheer descents are another example) are pumps that typically generate higher volumes of water flow at lower pressure. When running a waterfall, you don't need a geyser of water shooting 25 feet into the air but rather just a very high volume of water moved over a shorter distance. A lower pressure waterfall pump typically can't move water as far and as high as a pool pump.
The reason why you would want a high flow rate, low pressure waterfall pump is to avoid a condition called cavitation. Cavitation is when the water pressure and velocity gets so high that the flow becomes turbulent inside the pipes and pump. This turbulence causes the formation and collapse of water bubbles which can physically damage the interior of the pump's wet end (impeller and volute).
I have an example of this in my own pool - the pool builder put a 3HP Single-speed Pentair WhisperFlo pool pump on my waterfall. I had to add a valve to the return pipe to choke the flow off because, if I did not, the water velocity inside the pump would cause cavitation. It sounds like the pump has marbles rattling around inside it. A waterfall pump would have been a much better choice.
Low head water feature pumps also typically operate at lower speeds due to their motor design and thus use a lot less energy to move the water since high pressure is not required.
Waterfall pumps (low head or low pressure), or pumps that supply a water feature with an open end (sheer descents are another example) are pumps that typically generate higher volumes of water flow at lower pressure. When running a waterfall, you don't need a geyser of water shooting 25 feet into the air but rather just a very high volume of water moved over a shorter distance. A lower pressure waterfall pump typically can't move water as far and as high as a pool pump.
The reason why you would want a high flow rate, low pressure waterfall pump is to avoid a condition called cavitation. Cavitation is when the water pressure and velocity gets so high that the flow becomes turbulent inside the pipes and pump. This turbulence causes the formation and collapse of water bubbles which can physically damage the interior of the pump's wet end (impeller and volute).
I have an example of this in my own pool - the pool builder put a 3HP Single-speed Pentair WhisperFlo pool pump on my waterfall. I had to add a valve to the return pipe to choke the flow off because, if I did not, the water velocity inside the pump would cause cavitation. It sounds like the pump has marbles rattling around inside it. A waterfall pump would have been a much better choice.
Low head water feature pumps also typically operate at lower speeds due to their motor design and thus use a lot less energy to move the water since high pressure is not required.
Are high flow pumps generally low pressure?
In general, pool pumps are high pressure?
What about ponds? I'm guessing low pressure, low flow?
In general, pool pumps are high pressure?
What about ponds? I'm guessing low pressure, low flow?
- May 23, 2015
- 24,651
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
If you specifically look at the world of pool water pumps, you generally have two flavors - pumps that move a lot of water volume and operate at lower pressure (water feature pumps) versus pumps that move a moderate amount of water at higher pressure (pool pumps). There are also booster pumps which increase both pressure and flow of water to power a cleaner. The most important aspect of any pump is it's pumping curve which is a plot of pump head (pressure) versus water flow rate. That curve will also be separated into two regions - one region is where the pump operates efficiently (smooth water flow and no cavitation) versus where it operates inefficiently (turbulent flow and cavitation). So, when choosing a pump, you always want to know the details of your plumbing system (static and dynamic head loss) so you can ensure that the pump you choose is correctly sized for your application.
Is there some specific application you are looking at or is this just more of a general interest type question?
More a general question. When I look at parts for my pentair challenger, I'm always given two options. High flow or High pressure.
I remember the pumps used to have the "square" type of O ring and now the newer pumps I have are the round type of O rings for the diffuser and for the housing
I remember the pumps used to have the "square" type of O ring and now the newer pumps I have are the round type of O rings for the diffuser and for the housing
- May 23, 2015
- 24,651
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Ah, ok. Well, variable speed pumps have really made the distinctions a lot less important. I think Pentair is actually getting rid of its waterfall pump line as one can just use one of their variable speed pump to get the exact flow needed. Back in the old days, one needed to match their single speed pump to their plumbing to make sure everything ran smoothly. Nowadays you just slap a VSP on the pool plumbing and dial in the speed that makes everything work best. More expensive upfront but a lot easier down the road....
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