Pool pump replacement choices

[BobN54]

I need help in deciding on a replacement for our 1.25 SFHP Whisperflo WF-24, which has succumbed to salt-air corrosion deterioration. According to the charts, the WF-24 (installed by previous owner, and run 24x7) flows 88 GPM, at the 30' head I estimate for our installation. That pump seems way oversize. I'm considering the following options:

1. WFE-2 energy efficient single speed, 0.95 SHP : Rated 77 GPM at 30' head. Drop-in replacement. Comparing minimum amperage's (4.5 vs 7.1 for WF-24 ) this would yield $40/mo. power savings. But will it really save? I'm not sure if the WFE-2 has a smaller pump, or just a smaller motor spinning the same pump, and if there is enough reserve power to vacuum the pool.
   
2. Superflo VS: This seems like it would be a good choice except it has 1.5" fittings, which doesn't match my 2" plumbing. Interpolating the charts, it looks like I would need to set it up for around 2400 RPM to get the 30 GPM needed for the saltwater chlorinator to function properly. Am I right on that GPM figure for the chlorinator? What happens if the flow is less than that. Does it damage the chlorinator? I'm confused about use of the lower RPM settings. For instance, 1400 RPM line on the chart intersects 0 GPM at just 14' head; does that mean I would not be able to use that setting at all?
   
3. Intelliflo VS: Appears like it would barely be breathing hard to run my application. Flows 90 GPM at 2350 RPM setting. Pentair quoted me 33-50 GPM at 1750 RPM on 250 watts, which seems like a good fit. Would I run it like that 24x 7? That's $100/mo power savings. And at 1150 RPM, they quote 22-30 GPM at just 74 watts. Wow! Could I use that setting part of the day or will low flow harm the chlorinator ? Pentair says no worries about the intelliflo electronics holding up in our salt environment. Should I believe them? I'm a little nervous about that because corrosion is a problem around here; people tend to put in basic stuff and then toss it out after it corrodes away.

Thanks,
Bob

 

[RobbieH]

Mine at 30 gpm is only running 1840 rpm, and that's into 1.5" returns. It pulls 435 watts doing it.

Mine costs around $32.86 a month at $0.103 kWh, and that's at the 30 gpm we were talking about.

Either something's wrong with your math, or your power is outrageously expensive there.

Don't forget to factor the cost of the pump into the savings, so that you can figure out how many years it will take to be even. Some never hit a break point.

By salt environment, do you mean salt water pool? They are designed to work with them. Salt pools are 10x less salty than the sea.

 

[mas985]

WFE-2 energy efficient single speed, 0.95 SHP : Rated 77 GPM at 30' head. Drop-in replacement. Comparing minimum amperage's (4.5 vs 7.1 for WF-24 ) this would yield $40/mo. power savings. But will it really save? I'm not sure if the WFE-2 has a smaller pump, or just a smaller motor spinning the same pump, and if there is enough reserve power to vacuum the pool.

The maximum amp ratings on the pump label do not reflect actual power usage. You should use the Energy Star pump database to compare pumps (see spreadsheet in my sig).

Superflo VS: This seems like it would be a good choice except it has 1.5" fittings, which doesn't match my 2" plumbing. Interpolating the charts, it looks like I would need to set it up for around 2400 RPM to get the 30 GPM needed for the saltwater chlorinator to function properly. Am I right on that GPM figure for the chlorinator? What happens if the flow is less than that. Does it damage the chlorinator? I'm confused about use of the lower RPM settings. For instance, 1400 RPM line on the chart intersects 0 GPM at just 14' head; does that mean I would not be able to use that setting at all?

Head loss is not a constant and changes with the square of the flow rate. If you have typical 2" plumbing, 30 GPM would be about 1277 RPM.

Intelliflo VS: Appears like it would barely be breathing hard to run my application. Flows 90 GPM at 2350 RPM setting. Pentair quoted me 33-50 GPM at 1750 RPM on 250 watts, which seems like a good fit. Would I run it like that 24x 7? That's $100/mo power savings. And at 1150 RPM, they quote 22-30 GPM at just 74 watts. Wow! Could I use that setting part of the day or will low flow harm the chlorinator ? Pentair says no worries about the intelliflo electronics holding up in our salt environment. Should I believe them? I'm a little nervous about that because corrosion is a problem around here; people tend to put in basic stuff and then toss it out after it corrodes away.

Not sure where you are getting these numbers but the Intelliflo will only put out about 68 GPM at 2350 RPM, for 30 GPM it would be about 1035 RPM. Again for typical 2" plumbing.

 

[BobN54]

The maximum amp ratings on the pump label do not reflect actual power usage. You should use the Energy Star pump database to compare pumps (see spreadsheet in my sig).

Great lead. Thank you.

Head loss is not a constant and changes with the square of the flow rate. If you have typical 2" plumbing, 30 GPM would be about 1277 RPM.

That's helpful; I obviously have more to learn. I'm just coming up to speed; everything pool related has been handled by the pool guy up until now; which included running the 1HP Whisperflo 24x7, costing us ~$120/mo. of electricity. Fortunately, pool season is only 3-4 months here.

Not sure where you are getting these numbers but the Intelliflo will only put out about 68 GPM at 2350 RPM, for 30 GPM it would be about 1035 RPM. Again for typical 2" plumbing.

The 90GPM at 30' DH at 2350 RPM comes from the performance curve for the Intelliflo VS on Pentair's web site; hope it's okay if I link to it. I'll bet that's a best case number whereas your number is real world; constrained by 2" plumbing. My conversation with Pentair's Customer Support yielded these numbers; said to be from their testing:

1. 3450 RPM 66-100 GPM
2. 2400 RPM 44-70 GPM 593 Watts
3. 1750 RPM 33-50 GPM 250 Watts
4. 1150 RPM 22-30 GPM 74 Watts