Variable speed pumps should be limited to 2,500 rpm.

[JamesW]

In my opinion, they should make a line of variable speed pumps that are limited to 2,500 rpm.

The big benefit would be that they could install a larger impeller for the same horsepower.

This would allow the pump to be run slower for all flow rates.

The main difference would be that the pump would not be a good choice for high head applications.

The pump curve would be lower on the head curve but do better on flow.

Most pools don’t need to be able to generate 80 to 90 feet of head anyway.

Good design should eliminate almost all high head requirements for regular pools.

 

[JamesW]

The IntelliFlo is basically a WhisperFlo pump with a variable speed motor.

The WhisperFlo was designed probably 50 years ago.

At the time, the design might have made sense for a single speed pump, but it is no longer a good design for a variable speed pump for pools that are designed to limit head loss.

 

[PoolGate]

The pool industry is somewhat of a captive market with very little input from the consumers since they are insulated from the manufacturers via the middleman, or pool-builder. And where you should be seeing the industry want to end this marketing practice, you have makers like "Jandy" that do the opposite and make this even worse by specifically excluding the end-user from the process. This is why we don't see much change in pool offerings. I agree with you on this and many other enhancements could be made. For instance, why are JVAs not all variable as a matter of course? Why are pool automation systems archaic by any modern definition?

 

[JamesW]

A big part of the problem with the industry is a general unwillingness to change anything regardless of benefit.

Every company is afraid to innovate or take a stand that in any way contradicts decades old common practices.

That’s why chemistry is still practiced like it was in the 1950s and why pumps have been single speed high head pumps at 1,500 + watts until recent regulations are forcing them to change.

Builders are still choosing pumps that make no sense and cost 10 X too much to operate.

Most water feature pumps are WhisperFlo pumps even though the WhisperFlo is a horrible choice for a water feature pump.

 

[JoyfulNoise]

Most water feature pumps are WhisperFlo pumps even though the WhisperFlo is a horrible choice for a water feature pump.

This is my exact problem. My PB put a 1.5HP whisper flow on a waterfall feature. It’s a 2.5” intake pipe on a split wall drain with 2” discharge split to a 1.5” wall return and a 2” open pipe in the waterfall. There is not enough head loss in the plumbing and the pump operates WAY OFF its pump curve so much so that it will cavitate (yes, true pump cavitation) if I run both return lines full open. I had to install a shut off valve and literally choke the flow down to create enough back pressure to keep the pump from rattling itself to pieces. When I talked to the PB about it, he was like “That’s what Pentair had told me to do for years so I’m not changing it ...”. I rarely run the waterfall. All it needed was a simple 1/2 HP low head waterfall pump but they put a behemoth on it instead.

Someday I’ll get a newer VSP for the filter pump and then move my old VSP over to the waterfall and dump WhisperFlow in the trash.

 

[JamesW]

Waterfall pumps run at 1,725 RPM, which is half the speed but they use a bigger impeller, which is the basic idea of limiting the speed to 2,500 RPM and using a bigger impeller.

Slower speeds and bigger impellers work better for low head, high flow applications.

Any system that needs to go above 45 feet of head is probably a very poorly designed system.

They can still make the regular Intelliflo for pools that truly need high head, but probably 90% of pools would do better with a 2,500 rpm model.

Also, slower speeds are much quieter.

 

[JamesW]

They need to go through and redesign all equipment to reduce the head loss, especially heaters.

For heaters, they could require an external bypass valve that is driven 24 VAC directly from the heater controller so that you don’t need a thermal regulator and install a real flow switch (not a pressure switch) to verify proper flow before firing.

They should make the heat exchanger a single pass model instead of having the water make multiple passes.

 

[JoyfulNoise]

I thought the heat exchanger tubes on the Mastertemp all run parallel flow?

 

[JamesW]

It uses a two pass method.

The idea of a two pass exchanger is based on flawed logic.

The thinking is that you somehow get more heat by making multiple passes, but a single pass actually absorbs more heat and is hydraulically more efficient and it has at least 1/4th the amount of wall friction, which reduces mechanical erosion.

A single pass is better in every way.

 

[AUSpool]

A big part of the problem with the industry is a general unwillingness to change anything regardless of benefit.

Every company is afraid to innovate or take a stand that in any way contradicts decades old common practices.

That’s why chemistry is still practiced like it was in the 1950s and why pumps have been single speed high head pumps at 1,500 + watts until recent regulations are forcing them to change.

Builders are still choosing pumps that make no sense and cost 10 X too much to operate.

Most water feature pumps are WhisperFlo pumps even though the WhisperFlo is a horrible choice for a water feature pump.

Unfortunately I think the industry don’t know or don’t care and because the industry is purchasing new equipment on behalf of the end user there is no market drive for change.

We have a small pool and ordered the smallest VS pump and sand filter as part of the supply and build. I wasn’t able to be onsite when the steel and plumbing was installed for the shell and because it was a small pool it was plumbed with 1.5inch returns. Happy to have 1.5inch eyeballs bu it should have been plumbed in 2inch with sweeping bends or 45’s where possible. I was able to request 2inch plumbing to and from the shell with 45’s be used to connect all the equipment where possible. It could have been so much more efficient if done properly but efficiency is just doesn’t seem to be in the builders vocabulary.

 

[MostlyCanuck]

Builders are still choosing pumps that make no sense and cost 10 X too much to operate.

reflecting on my first build now, i think this is just a matter of serviceability. the simple SP pump that cost x10 to operate get serviced by the pool builder as part of regular maintenance, so they can make money longer term fixing a few simple parts at a time. with complex VS pumps, there is less servicing and more replacing the whole thing i think. if it breaks you just buy a new one. so it's better business for retail stores selling the more efficient VS pumps, and less advantageous for PBs or maintenance Cos doing weekly service. just my guess..

 

[JamesW]

the simple SP pump that cost x10 to operate get serviced by the pool builder as part of regular maintenance, so they can make money longer term fixing a few simple parts at a time. with complex VS pumps, there is less servicing and more replacing the whole thing i think. if it breaks you just buy a new one.

VS pumps are the same pumps as single speed pumps other than the motor and drive.

Wouldn't the service company make more money selling or repairing a VS pump?

In any case, the company has a fiduciary responsibility to do what's in the best interest of the customer.