Understanding Variable speed motor as replacement for single speed

[pebblensalt]

Can someone direct me to where to learn more about what I need to do to see if I want to do this? Our motor has stopped, I might be able to do bearings but it's at least 7 yrs old. I've seen posts that talk about running the variable speed motors from 12-24 hours a day and I have a hard time seeing that this would be more energy-efficient than running a single speed for 6-8 hours per day. It also sounds like I would have to change my pump impeller (or maybe whole pump assembly) to work properly with a variable speed motor. I also have a "the pool cleaner", and a circupool edge 40 saltwater chlorine generator (both recent upgrades).
I hate to miss an opportunity to upgrade to something more efficient but I also want to know the cost-benefit before jumping into the work.
Your comments/help are appreciated.

 

[Jimrahbe]

P,

I run my 3 HP IntelliFlo 24/7 at about 1200 RPM, most of the time.. To do that costs me less than $20 bucks a month.

What do you think it costs to run your single speed pump for just 6 to 8 hours a day??

That said the reason that you see a lot of us running 24/7 has nothing to do with the pump, it all has to do with running the Saltwater Chlorine Generator, or SWCG, 24/7.. We want to make chlorine 24/7, so the pump needs to run 24/7. This would be impossible with a single speed pump, but works like a charm with VS pumps.

Thanks,

Jim R.

 

[BowserB]

Not sure how it would work with an existing single speed pump, but according to Pentair, their VS pump uses 1/8 as much power at half speed as at full speed. So basic math would tell you that running at half speed twice as long still uses only 1/4 the electricity. I've looked at the panel on my VSF pump at a number of speeds. At full speed 3450 rpm I see 2530 watts. At 1700rpm, 298w, which is 11.8% as much power as at 3450. Slowest I've run it is 1300rpm and there it draws 111 watts. So at 1300rpm that's 37.7% as fast and 4.4% as much electricity. The savings from running a pump slower are staggering. I don't know that would work with a pump designed for a single speed motor. Check with the mfr is probably the next step. And you need some way to control the motor speed. How that's done might influence the economy of lower speed (solid state controls vs rheostat...not my area of knowledge.)

 

[pebblensalt]

P,

I run my 3 HP IntelliFlo 24/7 at about 1200 RPM, most of the time.. To do that costs me less than $20 bucks a month.

What do you think it costs to run your single speed pump for just 6 to 8 hours a day??

That said the reason that you see a lot of us running 24/7 has nothing to do with the pump, it all has to do with running the Saltwater Chlorine Generator, or SWCG, 24/7.. We want to make chlorine 24/7, so the pump needs to run 24/7. This would be impossible with a single speed pump, but works like a charm with VS pumps.

Thanks,

Jim R.

when I first installed my circupool edge40 (an upgrade larger than needed for my pool) SWG, it was making too much chlorine even with my 6-8 hrs. I thought the CYA (stabilizer) was how we managed consistent chlorine levels. Do you not need CYA if you have a variable speed pump going like you're doing?

 

[YippeeSkippy]

Absolutely you need the CYA..... the SWG makes small minute doses of chlorine in the pool. Without the CYA those doses of FC would be gone before the next hours dose.
If you were making too much FC you could either turn down the percentage on the SWG, or run the pump fewer hours per day. In the case of a VSP I would turn the SWG down.

Maddie

 

[nobody291]

I have the same pool cleaner as you and also a VSP. You might know this already, but the lower speeds of the VSP won't provide enough suction to drive the cleaner. I run my VSP 24 hours a day on a fairly low setting, and also schedule a higher RPM each day for increased skimming and for the cleaner.