Economics of Two-Speed Pump Operation

[MaxSmart]

Upgrading to a two-speed pump. Have heard it will be a big energy savings, but not clear as to how this works, how I should configure it.
My system is set up as such:

I currently run 6 hours on pool, then 2 hours on spa (allows solar heater to get spa hot-ish, in case I want to use it).
It seems like I need the full speed running at least a few hours, so the pool cleaner can work.
Can I run the solar heater at reduced flow? If not, then I don't see where I'm going to have savings, at least not during the non-summer months, because the solar makes a BIG difference in the pool temps.
Will I need to JVA the second-from-left valve, so that the skimmer is getting a larger % of the input during low-speed mode? (looks like I'm already losing one AUX to the dual-speed relay, not sure if I can spare any)
I'm assuming my Aqualink control panel is going to automatically increase to full-speed if I turn on the Heat Pump - is this correct?

 

[ajw22]

I don't think a 2 speed pump will work for you the way you want due to your solar setup and Aqualink and HP.

What revision level is your Aqualink? Jandy Aqualink RS - Further Reading

@PoolGate can a modern Aqualink do much with a 2-speed pump other then control the 2 speeds with two high voltage relays on two Aux circuits?

 

[MaxSmart]

Other question:

I don't think a 2 speed pump will work for you the way you want due to your solar setup and Aqualink and HP.

What revision level is your Aqualink? Jandy Aqualink RS - Further Reading

@PoolGate can a modern Aqualink fo much with a 2-speed pump otehr then control the 2 speeds with two high voltage relays on two Aux circuits?

I looked at the manual, seems like I turn a DIP switch and it turns AUX2 into a relay control for the special dual-speed relay switch I need to add. The original relay still gets the main pump relay wire, it feeds one leg of the output to the pump and the other leg to the DS relay switch. The DS relay passes the second leg to the pump by default, but when activated, becomes the common instead (so the pump is getting one phase + COM = 110v?). I hope I'm understanding this right.

 

[ajw22]

Yes, the Aqualink can control the 2 speeds using two relays. But I don't think it will change pump speeds automatically when your HP turns on or when your solar system needs higher speed.

You can set the schedule for when Aux1 speed or Aux2 speed runs but that is about all the Aqualink will do.

 

[MaxSmart]

I don't think a 2 speed pump will work for you the way you want due to your solar setup and Aqualink and HP.

What revision level is your Aqualink? Jandy Aqualink RS - Further Reading

@PoolGate can a modern Aqualink fo much with a 2-speed pump otehr then control the 2 speeds with two high voltage relays on two Aux circuits?

I believe it's Revision G (that's what's printed on the back of the circuit board, Jandy Industries Power Center Rev G)

 

[PoolGate]

I would go right to a variable speed model. But, the 2-speed should be configurable as to what speed you want when specific circuits (AUX) are activated. There is no logic that will reduce speed during running or change based on temp, for instance.

 

[ajw22]

Rev G is from 1997 and does not support VS pumps. You need at least Rev O for VS pumps.

 

[PoolGate]

Rev G is from 1997 and does not support VS pumps. You need at least Rev O for VS pumps.

In this case, I would upgrade the main board to a later rev that supports VSPs.

A 2 speed pump has 2 speeds. Low and high. Low is for things like circulation and to keep your SWG running. High is for things like heaters and water features. Below is a speed/cost chart for a Jandy VSP. If you can't go VSP, I would keep what you have and not waste the money for probably no ROI.

 

[ajw22]

Let's bring @Dirk into this discussion for what flow is required for the solar system. Not a lot of savings may be there if the solar heat requries a fairly high flow.

 

[Dirk]

I have an 8-panel array, 12' by 4' each. Each panel is most efficient at around 5GPM (you can get your number from your panel manufacturer). You have to multiply that per panel, so I need 40GPM. That requires 2200 RPM with my plumbing setup (each pool will differ a bit). So I'm guessing that's right in between high and low for a two-speed.

Running a solar heater below its optimum flow rate will make the water feel warmer, as the water stays in the panels longer, which might fool you. That won't heat your pool better. More flow with a lower heat differential will heat a pool more efficiently. Running higher flow than optimal is OK, heat exchange-wise, but the diminishing return factor is the pump energy required. In other words, you can run your two-speed at high-speed and get good solar performance, but you'll be wasting electricity.

If the pump puts out more than the solar panels can handle, then you'll need to bypass some of the flow, which is fine for the panels, but then you're waiting even more electricity.

You'll have a similar issue with the cleaner (which looks to be a suction-side vac). It, too, will have an optimal flow rate. Too low and it will under perform, too high and it will crawl out of the water and suck air. So you'd have to run that at high-speed and bypass some flow to optimize its performance, too. More wasted electricity.

I installed a flow meter for my solar, and my suction-side vac came with one. I optimized both systems by being able to adjust my VS pump to the perfect flow rate (RPM) for each. My automation controller handles the rest. I use just enough power to run both systems at peak effieciency, but no more.

SWG, too. When solar is off, my VS pump dials down flow to just above what my SWG needs. So that's another system that benefits from VS, without wasting any unnecessary energy.

The energy savings from optimizing flow for all three systems will pay for my pump at some point. (The entire cost of the pump, not just the difference between VS and 2-speed.)

With all those considerations, I predict that whatever you think you're going to be saving with a two-speed vs VS will not pan out.

Oh, and if your pump is within earshot of where you enjoy your pool, the difference in motor noise between a VS running at 2200 RPM and a two-speed running at full speed will be substantial.

 

[MaxSmart]

In this case, I would upgrade the main board to a later rev that supports VSPs.

A 2 speed pump has 2 speeds. Low and high. Low is for things like circulation and to keep your SWG running. High is for things like heaters and water features. Below is a speed/cost chart for a Jandy VSP. If you can't go VSP, I would keep what you have and not waste the money for probably no ROI.

View attachment 176240

Well, what I have now is achieving a GPM of 0. (it's dead, Jim)