Energy savings from a 2 speed pump

[Dirk]

If the variable speed pump can be set between 600 and 3450 rpm in 1 rpm increments, then it's a 2,851 speed pump.

A variable speed pump adjusts the power frequency to control rpm.

A two speed pump uses two sets of windings, a two pole set and a four pole set to allow for two speeds.

Thanks JamesW. Yes, I get that. But in terms of how I can set it up to operate, low for filtering, medium for skimming, high for cleaning, etc. I have a four speed pump. A "very adjustable" four speeds, but while in actual use, just four. So I would label my IntelliFlo an "adjustable speed" pump. The ones that can maintain flow settings, now those I would define as "variable speed" pumps, because they can "vary" their speed while operating. Mine, I can only "adjust" it to run one of four pre-set speeds. Semantics.

Now if the pool industry had its stuff together, they could have systems that monitor the clarity of the water, the flow through the filter, energy use (including variables like PG&E rate periods), the amount of crud on the surface or bottom, the air and water temperature, etc., all in real time, and throttle (vary) the pump speed, on the fly, to constantly solve for any given condition in the most energy-efficient way possible. (They're part way there.) They could then call them "dynamic speed" pumps! Copyright © 2018 Dirk Engineering, Inc.

Interesting about the windings. So those motors would not be user-adjustable. But I could swear I just read a few days ago, here somewhere, that someone knew how to dismantle or otherwise go inside a two speed pump and adjust in some way the RPMs of the two speeds. I didn't get the impression it had an onboard controller, like an IntelliFlo. This was something more rudimentary, that was like a set-it-and-forget-it adjustment. So that, if one needed a bit more or less RPMs on either setting, you could go in and tweak that speed. Did I imagine that?

I brought up the notion of variable or adjustable speeds for how Technikal could further pursue his energy savings. (Not that he necessarily needs to or wants to. Just jabbering to myself.) He's replaced his motor and now has a lower speed. He's getting savings. He's got a run-time constraint with his SWG, so he's stuck there in terms of savings. So what's left is finding a way to adjust the RPMs lower to use less electricity. He also needs a certain amount of RPMs to keep the leaves at bay. But if he could lower his low speed (while maintaining clarity) and briefly ramp up to his also-adjusted high speed for skimming a few times a day, controlled by a timer that can handle his two-speed, then he could conceivably eek out more savings while keeping his pool just as clean. Unless, like I said, I've imagined this whole adjustable two-speed motor thing.

I had a client that had invented a gizmo that bolted onto refrigerator fans, like in commercial refrigerators. It somehow controlled the fan speed, which greatly reduced energy use, while not compromising the motor. Not sure exactly what it was doing. Something like that might be useful in the pool industry, if it could be repurposed somehow, assuming the gizmo was less expensive than a pump/motor upgrade. You could just bolt it onto your old one-speed or two-speed and get instant savings. They sold the tech to some big refrigerator company. Their website explains it a bit.

OK, I think I just used more electricity typing this than the idea of it will ever actually save anyone!! :blah:

 

[Mayorb]

Just to throw my 2 cents in, VS pumps are running at about 3,000 rpms while on high, and about 1,800 rpms the rest of the time.
A two speed pump runs at 3,450 rpms on high, and 1,725 the rest of the time.
A two speed pump doesn't have a computer on its back, it easily assimilates into any controller with a two speed relay, even Intermatic has time clocks which run two speed pumps.
We are all products of our experiences, and I am still looking for a really good reason to recommend VS pumps to my customers.
Certainly, others feel differently.

 

[Dirk]

I can comment on how it makes sense for me. I have a legitimate reason for four speeds, and make good use of a fifth: freeze protection, filtering, cleaning, solar, and high-speed skimming. At 2600, solar is the highest, and freeze is 1000, the others in between, and none of them would be optimized, in terms of energy efficiency and performance, using either of the two-speed pump choices. 2600 uses significantly less energy than 3450. It is logarithmic, not linear savings. Solar and cleaning in particular need precise speeds to supply their respective hardware appropriately, and without wasting electricity, and freeze only needs a very slow speed, but for long, unpredictable periods of time. My needs require automation and VS. Only some of what my system does now is even possible with just a timer. And sure, all functions could be done with one of just two speeds, but at significantly higher energy cost. (Well, except for cleaning, my vac could not be used at either of those two RPM choices.) Now, would that higher cost ever add up to what automation and VS adds to system cost? I’m sure of it, but over what length of time I can’t say. In addition to energy efficiency, automation and VS also add convenience that is hard to quantify, but no less real.

Now that I’ve had both, I would not go back to two-speed for the money returned. I can certainly understand how some pool setups could be well served by just a two-speed pump. And kudos to you for not recommending to your customers more than they need. But is it really so hard to imagine how other pool systems would be better served by VS, especially when coupled with automation?

Just to throw my 2 cents in, VS pumps are running at about 3,000 rpms while on high, and about 1,800 rpms the rest of the time.
A two speed pump runs at 3,450 rpms on high, and 1,725 the rest of the time.
A two speed pump doesn't have a computer on its back, it easily assimilates into any controller with a two speed relay, even Intermatic has time clocks which run two speed pumps.
We are all products of our experiences, and I am still looking for a really good reason to recommend VS pumps to my customers.
Certainly, others feel differently.

 

[mas985]

Now if the pool industry had its stuff together, they could have systems that monitor the clarity of the water, the flow through the filter, energy use (including variables like PG&E rate periods), the amount of crud on the surface or bottom, the air and water temperature, etc., all in real time, and throttle (vary) the pump speed, on the fly, to constantly solve for any given condition in the most energy-efficient way possible.

But water clarity has very little to do with pump speed or run time for that mater. 99.9% of water clarity is due to just chemistry.

Interesting about the windings. So those motors would not be user-adjustable. But I could swear I just read a few days ago, here somewhere, that someone knew how to dismantle or otherwise go inside a two speed pump and adjust in some way the RPMs of the two speeds. I didn't get the impression it had an onboard controller, like an IntelliFlo. This was something more rudimentary, that was like a set-it-and-forget-it adjustment. So that, if one needed a bit more or less RPMs on either setting, you could go in and tweak that speed. Did I imagine that?

There is a lot of chatter on the internet about using a chopper/dimmer on the input line to the motor and it will slow it down to some extent before it ends up stalling but it has very undesirable consequences as well. The chopper lowers the average input voltage of the motor which in turn increases motor slip and slows it down but it also decreases efficiency quite a bit so the motor can easily overheat. So there is no real efficiency gain in doing this.

The other way to reduce the speed of an induction motor is to put a VFD on it but if you want the motor to last any length of time, you really need an inverter duty induction motor. The cost of the VFD + motor would well exceed some of the available VS motors so there is no benefit to doing that.

Those are the only two ways that I am aware of to modify the speed of an induction motor.

 

[Dirk]

But water clarity has very little to do with pump speed or run time for that mater. 99.9% of water clarity is due to just chemistry.

My fantasy system would be this big box, that had an "innie" on one side and an "outie" on the other, and just connect up to your pool. Inside there'd be magic elves that were constantly monitoring the water and taking all appropriate action. Runnin' the vac, the skimmer, the solar, filtering for particulates, whatever. Adding the chlorine and acid and other niceties, all while doing so at the best times of day and weather with an eye out for maximum energy efficiency! You know, all the stuff me and you and the OP are trying to get a handle on.

The technology is all there, for the most part, it's just a matter of putting it all together. No Steve Jobs to rely on for this, I'm afraid.

Oh, and I only want to pay about $1000 for it!! 10 year warranty included!

That client of mine was probably using some variation of what you describe for reducing motor energy, but as you point out, it's probably more expensive than a VS. So sorry, OP, I couldn't come up with any better way than you already have to save you some dough...

(Not that you asked, but that's never stopped me before!!)