Variable Speed pump

[Fae]

Everything I can find to read says a variable speed is the best way to go to replace your single speed pump. It all sounds like clever marketing to me. If you could go with a lower speed pump why not just get a less powerful single speed pump which would cost you 1/3 as much?

Anyway, I have 2 hp pump for my 15k pool and I think it's way over sized. I have a Jandy 200 SF Cartridge Filter if that makes a difference. My pool equipment is very close to the pool so calculating pipe lengths (plumed with 2" pipe) would not make enough of a difference to warrant a bigger pump.

Anyway, when I need to replace it can anyone see why I couldn't just run a smaller pump longer to get the same effect as a variable speed pump?

 

[Oly]

More options, more better. The VS pump is a big benefit when the pump is run for many hours of the day and electrical rates are high. Many pool owners operate a Salt Water Chlorine Generator which can operate at pump RPMs as low at 1200 to 1300. Dialing in your system allows you to observe the optimum and minimum pump RPM for skimming and to schedule these runs throughout the day. A VS pump also can be ramped up for pump activated cleaners and water features that can be scheduled automatically each day. It really depends upon your system needs and your electric costs.

 

[mknauss]

Welcome to the forum.

There also is a pesky thing called Federal Regulation.

Pump DOE Regulations - Further Reading

www.troublefreepool.com

 

[pjt]

It all sounds like clever marketing to me.

You're not getting scammed when you purchase a VSP. After a quality test kit, it's probably the best money you'll spend on your pool.

If you could go with a lower speed pump why not just get a less powerful single speed pump which would cost you 1/3 as much?

That would be like buying a car that only goes one speed. You want the range of capability, economy, and performance that a VSP provides.

 

[JoyfulNoise]

From a very technical post written by @mas985 -

But what do these equations really tell us? For one thing, a reduction in speed has a proportional reduction in flow rate but has a much more significant reduction in the required HP required to generate that flow rate. This is the primary reason a two speed or variable speed pump can save so much energy at lower speeds.

For example, low speed of a two speed pump has about 1/2 the flow rate as high speed and the affinity equations tell us that it requires only 1/8th the power of high speed. Unfortunately, two speed motors lose about half their efficiency at low speed so the energy use is only about 1/4th of high speed but still significant.

In other words, a variable speed pump allows you to adjust the rotational speed of the motor which has a huge impact on the amount of energy used. They also allow you to fine tune the flow rate of water through your plumbing system so that you are efficiently matching the amount of electrical energy consumed to the desired flow rate of water.

Yes, you can simply put a smaller HP single speed pump on the pool’s plumbing but it may not produce enough flow rate for your plumbing and equipment or it may needlessly waste electrical energy doing it.

 

[1poolman1]

Everything I can find to read says a variable speed is the best way to go to replace your single speed pump. It all sounds like clever marketing to me. If you could go with a lower speed pump why not just get a less powerful single speed pump which would cost you 1/3 as much?

Anyway, I have 2 hp pump for my 15k pool and I think it's way over sized. I have a Jandy 200 SF Cartridge Filter if that makes a difference. My pool equipment is very close to the pool so calculating pipe lengths (plumed with 2" pipe) would not make enough of a difference to warrant a bigger pump.

Anyway, when I need to replace it can anyone see why I couldn't just run a smaller pump longer to get the same effect as a variable speed pump?

There are many, many reason to have a VSP beyond energy savings (its not clever marketing). That being said, you can filter your pool well with a single speed pump that meets the new DOE regulations. While Pentair does (or did) make one model in both WhisperFlow and Max-E-Pro lines, they are impossible to get. Waterway makes a Power Defender 110 pump that meets DOE regulations and would work well on your pool. I have installed 2 since the July 19 DOE regulations went into effect and they work well. Waterway is not as big a name as the "Big 3" in the pool industry, but they make a solid product.
The only problem I have ever experienced with the California-legal Waterway pumps I installed (about 40) was with two. Both times it was a motor that went bad and Waterway doesn't make motors, they were early Century motors made in China (as they all are now) that had issues. The problems seem to have been corrected.