Feature Request: Why don't pump controllers dynamically set RPM for heating with solar panels

[mas985]

Perhaps instead even running it low speed ALL the time is really only slightly less efficient and thus the even better financial move...

It is a good compromise and it costs nothing to implement. As I said before, I doubt you will notice a difference in pool temps, although you will in energy bills.

 

[Dirk]

For practical purposes, the best option is to maintain the flow in the range that the manufacturer recommends with a preferred flow near the lower end with a few GPM for margin.

Exactly, exactly, what I do.

If others have formulas, spreadsheets or actual results that convince themselves that they have a more cost effective way to heat a pool, I concede that's what they should do.

Meanwhile, I choose to believe what solar panel manufacturers have come up with. This isn't scientific, but here's my "math:" if a manufacturer could show how their panels heat a pool just as well at half the flow rate as conventional practices do, I think after no time at all the others would have figured that out, too, and included it in their owner manuals. Similarly, if running at reduced flow in the morning and optimal flow in the afternoon was more efficient, more cost-effective, they would include those instructions as well, since most of the pool automation controllers in existence could be scheduled to do so.

I have no doubt your theories and math are sound, just as I have no doubt that manufacturers came to their optimum flow rates based on real-world testing, not just math. (Though I can't prove either.)

I also have no doubt that reducing the flow in the morning will still heat your pool somewhat, while saving electricity, it'll just heat it less. I don't think any of you all were claiming otherwise. So that's fine, spend less on electric bills by running a slightly cooler pool.

Thanks for all the effort put into sharing your points of view and explanations and data! Mark, I especially appreciate the work you did with all the spreadsheets and tools.

That all said, I'll stick to one of my very first conclusions, which inarguably is the absolute most cost effective way to heat a pool 5-10° a day: install a PV solar system. At around the 5 year mark the system will have paid for itself and heating your pool we be at zero cost, no matter how you run the heater and pump. If you're looking to save money long term, that's how to do it. If you're going to move in less than five years, then... ya know... do what works for your pool.