Pool Pump Craziness - Single Speed, Two-Speed, Variable Speed and Efficiency - Page 1
Forum section: electronics / general

author: Fried Chicken
author_rank: Regular Contributor
timestamp: August 27, 2025, 03:16:24 am
content: What kinds of motors are used in pool pumps, and how do variable speed motors produce such efficiency gains?It's my understanding single speed motors are simply induction motors running at a fixed RPM based on the number of windings in the stator and the frequency of the AC power. They induce a magnetic field in the armature (hence induction motor), and have been around since forever.I believe these are also used in Air-Conditioning compressors, and use a capacitor for starting:Quote from: wikipediaTwo-speed pool pumps use induction motors but have different windings active whether they are using the two poles of the 240VAC supply, or just a single pole 120VAC.New on the scene (read: 21st century) are what the industry calls "variable speed" motors. It's unbelievably difficult to get past marketing jargon, AI generated websites, and neutered search engines to find out exactly what's going on here, but one thing is for certain: these use controllers (complicated circuitry) to "control" the motor to alter the speed/rpm of the motor. What's so far unclear to me is what type of motors are employed here, but my gut tells me it's aVFD driven AC motor. I am guessing. All I definitively know is that all the VS pumps come with a controller, cost exorbitantly more than single-speed or even two-speed motors, and have a lot of anecdotal reliability concerns. Delving now more into pool application territory: these controller PCBs sit basically in hell, often directly on top of the motor, and are so expensive in their replacement when they fail, you can theoretically buy a whole new pump.What I want to understand: how/where the efficiency gains are made with these variable speed motorsbeyond simply the cube relationship between speed and torque/power required in fluid pumping applicationsWhy then, with with this relationship being well known for possibly centuries, did we ever even build pools with such high speed flow in the first place?The contemporary application of variable speed motors comes from an understanding that the lower speed can still provide the required filtration, skimming, and dissolution of chemicals in the pool, with high speed often only being required for a few hours each day for skimming or otherwise.Why then go through the trouble then, of installing large, expensive, complicated, and unreliable variable speed pumps when one could simply install a much smaller pump? Alternatively, since certain applicationsdorequire periodic larger pumps... why not just install one large pump and one small pump and alternate their drive? In effect this is what two-speed pumps do, two motors in one.But then the argument for the variable speed pump goes: you can run itsoslowly, that only that it's onlysippingwater through, but this still provides the benefits required... Ok, why not install a 3rd tiny little pump? Or do these controller-driven motors offer such higher electrical efficiency to their synchronous counterparts?The U.S. government has now gone so far as torequire pool pump motors be variable speed starting September 29, 2025.I've even seen statesban the import of single speed pool pumpmotors.Anecdotally, and personally, every pool industry insider I have spoken to not only recommends against the variable speed pool pumps, but actually suggests I cling to my existing pool pump motor or as long as possible - that the costs don't outweigh the benefits; that the added complexity, reliability concerns don't track, and that the savings are not as pronounced as advertised.I'd really appreciate a a more empirical approach here with this discussion, referencing the underlying physics and engineering, not anecdotal reports of what your pool install might have saved you on your power bill. The reason is that I think something isn't being said here. Why not install 3 inexpensive synchronous motor pumps operating at different speeds/power levels (with the appropriate check valves so they don't fight one another in the plumbing, and hooked up in such a way that they don't run simultaneously). Why even design pools with such high power requirements in the first place? Why do the plumbing in such a way that such high speeds are required for normal operation.It just doesn't make sense to me.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 27, 2025, 03:36:15 am
content: I don't know the answers, but on the empirical side I know that all of the PVC piping used in pools lives in hell also, and doesn't last much longer than the motors. So the extra plumbing required for multiple motors is a real downside. Multiple motors has direct cost and at three you are approaching the VFD costs. And multiple motors would require a controller to run them. Could be as simple as additional timers, but guess what? Those aren't terribly reliable in the pool environment.I suspect that the savings touted by the government and manufacturers is purely theoretical, with no costs associated with reliability and probably unrealistic (hoped for) procurement costs. And as you are discovering, the factors are so complex that there isn't solid enough real world data to support or refute the government position.

author: ejeffrey
author_rank: Super Contributor
timestamp: August 28, 2025, 02:44:38 am
content: Quote from: Fried Chicken on August 27, 2025, 03:16:24 amFor the same reason why even now people install cheap, inefficient single speed unidirectional air conditioners, even in mild climates instead of reversible heat pumps with variable speed motors. The equipment and installation is marginally more expensive. The installers are incentivised to offer the lowest install cost to win the bid. Consumers don't know to demand a more efficient products, so installers don't have a reason to learn, and small volume keeps it a niche and overpriced option in the consumer space.Also, backyard pools are generally owned by people who are not really worrying about the size of their utility bill.Anecdotally, and personally, every pool industry insider I have spoken to not only recommends against the variable speed pool pumps, but actually suggests I cling to my existing pool pump motor or as long as possible - that the costs don't outweigh the benefits; that the added complexity, reliability concerns don't track, and that the savings are not as pronounced as advertised.QuoteYou already understand. It's the cubic dependence of power on flow rate. Running a pool pump slower for longer *massively* reduces the power consumption. There isn't some magic secret.QuoteBecause bigger pipes, pumps, and filters are more expensive and take up more space. Secondary pumps take up more space and require more fittings. Adding variable speed drive is by far the simplest and likely the cheapest way to improve efficiency.Its not like a VFD is new or exotic technology. VFDs have been used for ages in commercial HVAC and industrial applications. The motor itself can be the exact same induction motor you would use in a fixed frequency application. What's different now is that power semiconductors have gotten way better and cheaper so that they can be affordable and reliable in far more applications. I don't own a pool so I haven't dealt with this: maybe some pool pump variable speed controllers are unreliable, and maybe some manufactures are overcharging because it's a "new" technology in the backyard pool industry. But that's not fundamental or anything.

author: ejeffrey
author_rank: Super Contributor
timestamp: August 28, 2025, 03:07:19 am
content: Also a large pump mostly run at 20-50% speed will itself be more efficient and run cooler. The efficiency difference isn't huge compared to the reduction in pumping losses but it's going to run cooler and possibly last longer that a secondary small pump run at full speed. So while the VFD itself adds cost, it might reduce maintinence costs of your motor and pump.

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: August 28, 2025, 05:14:57 am
content: Compared to the historical price of electricity, a VFD or multiple pumps of different sizes would not break even before the pump(s) died. Multiple pumps won't fly on a practical level either because it takes up too much room and requires check valves to prevent backflow through the unused ones.Variable-frequency pool pumps are an exercise in clever marketing. If anything, I would buy a separate VFD controller and continue using cheap single-speed pool pumps.Now that electricity is getting more expensive and VFDs (as with all electronics) are getting cheaper, it's possible to make the argument that it's something you absolutely have to have now. Everyone likes gadgets.

author: Fried Chicken
author_rank: Regular Contributor
timestamp: August 28, 2025, 01:52:44 pm
content: Can someone answer for me the most basic question of what types of motors are used in these pool applications?

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 28, 2025, 04:09:12 pm
content: In the ones I have owned, bog simple non variable speed types, they are exactly the induction motors you mention in the first post. With the caveat that the speed is not dependent on voltage connection.

author: David Hess
author_rank: Super Contributor
timestamp: August 28, 2025, 06:41:40 pm
content: What is the advantage suppose to be?Induction motors operating into their design load are efficient, and a VFD drive is not going to make them more efficient, although it could increase the power factor. It is not like we are talking about a shaded pole motor being replaced by an electronically commutated motor where there is a real efficiency gain.Is this to make up for an induction motor which is not properly matched to the pump?The pools we have had all had two induction motors on timers, with one for filtering, and another for the booster pump to operate the pool cleaning robot or thing or whatever it is called.I asked the Google AI and received a bunch of bullshit answers.

author: Fried Chicken
author_rank: Regular Contributor
timestamp: August 28, 2025, 11:12:32 pm
content: Quote from: CatalinaWOW on August 28, 2025, 04:09:12 pmre-read what I said:Quote

author: ejeffrey
author_rank: Super Contributor
timestamp: August 29, 2025, 02:20:14 am
content: Quote from: David Hess on August 28, 2025, 06:41:40 pmNo. It's because you sometimes need high flow for cleaning and you need higher or lower exchange rate depending on the temperature. So the pump and motor are sized for the maximum needs. In normal use they are run intermittently to get a target number of liquid exchanges per day perhaps 8-12 hours per day. The motor itself is running "efficiently" in that electrical energy is converted efficiently to mechanicical work. But that's misleading because you are just working against drag in the pipes and filters.The idea of a dual speed or variable speed pump is that during normal operation you run the pump continuously at 30-50% speed and the energy required is reduced by 4-9 times. You can still increase to full speed when needed.

author: Fried Chicken
author_rank: Regular Contributor
timestamp: August 30, 2025, 04:43:52 am
content: So I imagine the variable speed motors use a permanent magnet motor... driven by a 3-phase inverter?

author: David Hess
author_rank: Super Contributor
timestamp: August 31, 2025, 01:28:40 am
content: Quote from: Fried Chicken on August 30, 2025, 04:43:52 amI thought they would still use a single phase induction motor because it is less expensive.

author: johansen
author_rank: Super Contributor
timestamp: August 31, 2025, 01:42:51 am
content: how many people on this forum have ever taken one apart? i'm at probably 3 of them. they are all dual winding, 1750/3500 rpm motors.as for residential pool pump motors, its pretty righteous of the federal government to mandate variable speed motors that will never pay for themselves, when 90% of residential hot tubs are heated with resistive heat!

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 31, 2025, 04:24:58 am
content: YouTuber Two Bit DeVinci just posted a four year update on his plan to be energy self sufficient. In it he has actual numbers on his conversion from a single speed pump to a VS pump. In his case the savings were real and large. It seems that he still isn't exactly comparing apples to apples. He wasn't necessarily running the single speed pump the minimum amount required, and probably is running the VS pump closer to the minimum acceptable amount even though he is running it longer. And his electric rates are eye poppingly high.

author: johansen
author_rank: Super Contributor
timestamp: August 31, 2025, 05:34:23 am
content: Quote from: CatalinaWOW on August 31, 2025, 04:24:58 amSo .what?Pools when properly maintained dont even need a pump.

author: David Hess
author_rank: Super Contributor
timestamp: August 31, 2025, 01:42:39 pm
content: Quote from: CatalinaWOW on August 31, 2025, 04:24:58 amDid he include a quantitative measurement of how well the pool water was filtered?

author: Fried Chicken
author_rank: Regular Contributor
timestamp: August 31, 2025, 03:25:33 pm
content: Quote from: johansen on August 31, 2025, 01:42:51 amAre you referring to the 2-speed pumps or the variable speed pumps or both?

author: bdunham7
author_rank: Super Contributor
timestamp: August 31, 2025, 06:46:37 pm
content: Quote from: Fried Chicken on August 27, 2025, 03:16:24 amI can give you a detailed explanation that applies to Pentair pool pumps, I'm not sure about other brands. I have two pool pumps and I custom-built them both from various parts to get what I wanted.First, with the Pentair "WhisperFlo" line, they come in sizes from 0.5 to 3.0HP and all have the same basic volute (housing) size. The only significant differences are the motors and the impellers. The various impellers are of an enclosed design and all very similar radially. They vary mostly in thickness with very thin ones for 0.5HP and the thickest for 3.0. The motors are typically a PSC design as there is very little starting torque required, although some seem to have centrifugal starters and auxiliary windings and perhaps two capacitors. So YMMV there, but all of mine have single capacitors except my custom two-speed. The bottom line is that they are all some flavor of a single-phase induction motor.The motors are nominally 3600RPM (2-pole) and most can be run on 120 or 240VAC, although the voltage and speed are entirely unrelated. Some are only 240VAC. Two speed motors are 4-pole in the lower speed. The two speed models from Pentair reuse the capacitor and windings from the two-pole configuration and IDK the exact details but this makes them very inefficient on the lower speed. Essentially cutting the speed in half reduces the pump input power by a factor of 8 and the flow by a factor of two, so 4X the mechanical efficiency. However, the efficiency of the motor drops by about 50%, so you only get double the electrical efficiency if that. What I did was made a two speed pump by using a specific 1.5HP aftermarket (Century) motor that has a completely separate set of windings, a relay and a separate smaller capacitor for the 4-pole mode. Thus I get 80-85% motor efficiency no matter which mode I'm in.Variable speed pumps use an ECM or BLDC motor and I'm pretty sure they are the permanent magnet type, not an induction motor with a VFD. That may not be true for all of them, but it is for at least some. You can tell the difference with that type of motor because it "cogs" when you turn it by hand. The typical original Pentair "Intelliflow" motor, as they called them, used a very similar housing to the Whisperflow line but with an impeller sized for 3HP. You would the program it for high and low flow rates and you could set those to whatever you wanted. I think the efficiency of the motors was like 93%, so not massive gains but the adjustability was also a potential efficiency gain. There's a lot more variety on the market now so YMMV--a lot.There are reasons you need variable or two-speed pumps. Some systems will not prime at the low speed, for example. Mine will after a long while but I had to take some care to build it so that it would. It is still programmed for 5 minutes at high speed before switching to low. Vacuuming, floor cleaning and other cycles need more power, overnight or all day filtering work better at low flow rates. A variable speed pump might be able to run just hard enough to operate a floor cleaner without using full speed.The reason you don't want multiple pumps is that then the plumbing and valve controls get complicated. My spa/pool/heater/dual filter setup is complicated enough and I really worked to make it as simple as possible. My pool guy back in the day (over decade ago) told me the same thing about not getting variable speed pumps. I think that advice is outdated now and when it's time for a replacement or major upgrade, I'll be gettting a variable speed unit. I have no doubt that two-speed and variable speed motors can save energy, how much just depends on how far from optimal your fixed-speed system is currently.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 31, 2025, 06:50:17 pm
content: The video has no quantitative information on filtering. Just a statement that they were told when they bought the residence to run the pump for one duration, and they chose to run the new pump a different amount. Durations were given, but I don't remember.I am a very happy ex-pool owner, but would love to hear how to maintain one properly without a pump. Apparently the knowledge is not widely known because no one I know of has ever achieved it.

author: bdunham7
author_rank: Super Contributor
timestamp: August 31, 2025, 06:53:45 pm
content: Quote from: CatalinaWOW on August 31, 2025, 06:50:17 pmYou simply add some aquatic plants, some mosquito fish and maybe some frogs, tilapia and little catfish. Or koi, but that's been done to death.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: August 31, 2025, 10:29:30 pm
content: Quote from: bdunham7 on August 31, 2025, 06:53:45 pmI can see where you might make that work for a pool. Though aquatic plants in something with a minimum depth of a meter seems a bit challenging. And from my experience with aquariums getting everything to balance out without pumps and filters is tricky.On the other hand it is trivial to achieve a smelly algae clogged mess, catfish not withstanding.

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: September 01, 2025, 05:04:22 am
content: Quote from: Fried Chicken on August 28, 2025, 01:52:44 pmAC induction (asynchronous) motor, but your first quote asks about "fixed RPM". Technically that would be a synchronous motor, those always turn at exactly the speed determined by number of poles and mains frequency. AC induction motors always have some "slip", that is they turn slightly slower than their synchronous speed based on how much load they're under. They need a small slip angle in order to develop torque.

author: Marco
author_rank: Super Contributor
timestamp: September 01, 2025, 08:03:17 am
content: Quote from: CatalinaWOW on August 31, 2025, 10:29:30 pmHad a pond a long long time ago and pumping through a separate bog worked well enough.Though I didn't, pond tinkerers also use air"lift" pumping. The bog filters tend to be relatively large, so no need for a lot of head to push water through small filters.

author: Fried Chicken
author_rank: Regular Contributor
timestamp: September 01, 2025, 03:44:11 pm
content: Quote from: bdunham7 on August 31, 2025, 06:46:37 pmSo PSC is permanent-split capacitor; where the capacitor causes a phase-shift in the AC for starting (where some of them then disconnect the capacitor centrifugally once started).QuoteWhy they would do this is completely beyond meQuoteThis is the route I would go. I still harbor reliability concerns regarding the digitally controlled motors, and the price remains astronomical (for the big three (Jandy, Hayward, Pentair). Do you have the details of the Century motor you used, as well as how you configured the electronics that you could time the low and high speed settings?Were I to go with a computer-controlled motor, I would probably getthis one, ordered along with full set of replacement parts, and would still be cheaper than the big three's offerings.QuoteSo ECM is Electronically Commutated Motor - specialized brushless DC motors with a permanent magnet design and electronically controlled commutation replacing the brushes... For pool pump applications these would have to rectify the AC into DC first. Incredible the efficiency they can achieve given that whole process. I'd imagine the "premium" offerings do a better job at this than the "cheap" offerings... but with expensive electronics.I just want to clarify all this for myself.QuoteIt gets complicated but not necessarily unmanageable. You'd have to have some electronics so that one motor runs without the other running, as well as check valves. If this is the only drawback, I could see an additional benefit of motor redundancy should one need servicing or otherwise.What century motor did you end up using? I think that's the route I'm going to follow. Old pumps are plentiful on the used market, and parts remain widely available (although the prices have increased literally 5x since the before times). Once again your clairvoyance on our mutual interests is like a glass of icewater to someone in hell!

author: bdunham7
author_rank: Super Contributor
timestamp: September 02, 2025, 05:20:09 am
content: Quote from: Fried Chicken on September 01, 2025, 03:44:11 pmIt was cheaper and I think there was a regulatory or credit scheme at one point with rebates on two-speed motors just like there are regulations and credits for the variable-speed models now.QuoteOne like this, possibly this exact model. It's been going now for over a decade, even survived a fire.https://www.inyopools.com/Products/07501352050201.htm

author: johansen
author_rank: Super Contributor
timestamp: September 02, 2025, 06:16:27 am
content: I made a 3600 rpm shaded pole motor from a 1800rpm shaded pole motor by cutting the windings and reconnecting, then adding a capacitor in series with 2 of them. Only problem is, it runs on 60vac.The 2 speed dallander winding does the same thing effectively, there are two ways to do it. You can run the windings at full voltage to preserve full motor torque (so half the hp at half speed) or you connect the windings in series so they get half the voltage at half speed. This makes for a fourth of the torque, which is enough for pumps.The downside is, the windings have to occupy less space in the core so that in low speed, the magnetic flux has somewhere to go between the coils to get to the back iron behind them, hopefully without saturating the teethIn real life its common for a 5hp 2 speed motor to be 50% more line amps than what is typical for a single speed motor. 70% power factor instead of 85

author: pnuding
author_rank: Newbie
timestamp: September 02, 2025, 09:36:35 am
content: Here in Europe most brands offer pool pumps in single phase or three phase versions. So what I did was get a three phase version and a cheap second hand VFD to run it.Many of these allow for some configuration, so I have mine running at low speed most of the time, with a few minutes of almost-full speed every 90 minutes.The point of the full speed phase is just to push dirt into the skimmers. In my case the water surface is highly suspectible to wind and the dirt may never make it there at low pump speed.Low speed in my case is 23Hz determined by the minimum flow rate my salt water chlorinator needs to work reliably. That brings my 1kW pump down to 284W.In winter months when that's off I reduce further to about 18Hz. That takes it to around 150W. Below that the efficiency gains stop being relevant in my setup.Plan for some experimentation, I had pipes resonate at some frequencies.Overall besides the immediate efficiency gain, the pump's lifespan should improve as the seals and bearings receive a lot less vibration at slower speeds, and the VFD's ramps also avoid the jolts on power.And as an additional trick you can save water when backwashing the sand filter: for backwashing I overclock the pump and run it at 64Hz (that's as much power as my VFD can handle). With that more violent flow, I get the dirt out of the filter more easily and get to clear water in around a minute, where at normal speed it took 4 or 5.

author: Fried Chicken
author_rank: Regular Contributor
timestamp: September 03, 2025, 02:37:14 pm
content: Quote from: bdunham7 on September 02, 2025, 05:20:09 amI saw that one as well. How do you control it?

author: bdunham7
author_rank: Super Contributor
timestamp: September 03, 2025, 03:03:32 pm
content: Quote from: Fried Chicken on September 03, 2025, 02:37:14 pmI use the Intermatic P1353ME three-circuit controller. It is programmable and it has a two-speed setting that prevents circuits 1 and 2 from ever being on at the same time. I use 1 and 2 for the main pool high and low speeds and the circuit 3 for the spa pump which is separate so that only the spa pump goes through the heater. There's a nice control subpanel box you can get that holds it all and allows you to add switches, circuit breakers and so forth. The prices have sure gone up...https://www.poolzoom.com/intermatic-enclosure-w-1-p1353me-60amp-pe25300.html

author: Fried Chicken
author_rank: Regular Contributor
timestamp: September 03, 2025, 03:29:37 pm
content: Quote from: bdunham7 on September 03, 2025, 03:03:32 pmThanks man, I appreciate you

author: Fried Chicken
author_rank: Regular Contributor
timestamp: September 21, 2025, 01:18:26 pm
content: Quote from: bdunham7 on September 02, 2025, 05:20:09 amI ended up buying two of this exact motor along with a Whisperflo pump fromPerry's Poolafter asking what they recommended and simply ordering that. Might buy an additional pump so I have two if/when servicing is needed.I'm now trying to figure out the theory of operation of the 4-pole design, and then how to wire it. Idk how/why, but I'm struggling to find this information.I'll also have to figure this out for the controller.

author: johansen
author_rank: Super Contributor
timestamp: September 21, 2025, 10:38:00 pm
content: Quote from: bdunham7 on September 02, 2025, 05:20:09 amIts just 2 wires. Com and L1 or L2.Two completely different motor windings.

author: Fried Chicken
author_rank: Regular Contributor
timestamp: September 22, 2025, 01:07:20 pm
content: Quote from: johansen on September 21, 2025, 10:38:00 pmThat doesn't make sense as the unit needs the 240V to operate. If it only winds across L1 and Com or L2 and Com, it's only getting half the voltage.

author: bdunham7
author_rank: Super Contributor
timestamp: September 22, 2025, 10:00:59 pm
content: Quote from: Fried Chicken on September 22, 2025, 01:07:20 pmThat's all pretty confusing! L1 and L2 refer to the incoming phases or hot legs not the windings and there is 240VAC across them. COM, however, is not neutral and you don't need, nor should you have, any neutral wire to this motor. COM is where one of the phases is permanently connected. To make it more confusing, they've labeled this as "L2", but in reality L1 and L2 are pretty arbitrary. To make the motor run on HI you connect the other phase to the L1/HI connector, for LO you connect to the A/LO. The motor takes care of the rest, as far as the internal windings go it is complicated and controlled by a relay. You should never connect both at once! However, TBH I've no idea what actually happens if you do.I'll note that this motor is an absolute beast to get the wires attached properly and the fluid-tight whip installed. I recommend you do it on a bench or in the open and then install the whole thing with the wiring already done. Also, the LO terminal only draws 1.6A at full load so you don't necessarily need a heavy wire for that, code be damned.

author: johansen
author_rank: Super Contributor
timestamp: September 23, 2025, 12:34:15 am
content: Quote from: bdunham7 on September 22, 2025, 10:00:59 pmIt might run on low speed if you ran both in series, however the start switch would never open so the high speed start capacitor would be left in circuit and would fail after some time.The 2 pole winding would have current flowing causing the magnetic field on one side of the motor to be stronger than the other side, where the coil would be opposing the 4 pole winding. The capacitor start winding would likewise be opposing one side of the motor but not the other.basically it contributes nothing except further saturating one side of the core but not the other.

author: Fried Chicken
author_rank: Regular Contributor
timestamp: September 24, 2025, 12:31:34 pm
content: Quote from: bdunham7 on August 31, 2025, 06:46:37 pmHow did you achieve this? Both the priming on low speed, and the programming so it runs high for 5 minutes before switching to low?I've found some resources:https://www.troublefreepool.com/wiki/index.php?title=Pump_Basics#Pump_Self_PrimingIn that linked video is what looks like a P-Trap... maybe not a bad idea to install. I'm preparing an order of PVC pieces

author: bdunham7
author_rank: Super Contributor
timestamp: September 24, 2025, 09:17:22 pm
content: Quote from: Fried Chicken on September 24, 2025, 12:31:34 pmThe Intermatic timer I posted allows you to manually set up programs, I just set up 5 minutes on high immediately followed by several hours (or whatever) on LO. There's no automatic setting, you just have to get the two programs to overlap. The model I posted does have setup modes and one of them is specifically for two-speed pumps using CH1 and CH2, in that mode it will never allow both to be active at the same time even if you program it to.For the priming, the pump is at a local low point in the system. The pipes from the pool come in underground and go up to some valves, then down to the pumps. The outlets of the pumps have big check valves installed on near their outlets. Everything is greased and sealed so there is no air leakage, but even if there eventually is the pump itself is always full of water. Priming on low speed is difficult and I wouldn't expect all systems to be able to do it.