Pump Efficiency

[Big_D]

Richard,
I went with and Intelliflo in June of last year when I built my pool. I also went with the Intellitouch system because of the Intelliflo. I move 40 GPM at under 600 watts. When I run my Cleaner it goes up to 70 gpm. When I want to make the spillway really move it goes to 100 gpm. When in the spa mode it is set for 100 GPM for spa or with the blower it is at 120 GPM. I stubbed for a solar but have not installed one yet, but when I do I will also program flow for that. What is great is the ability to tweak flow rates any time I want to. Power cost went through the roof this past year so I programmed for most efficient flow rates. I was shocked when I used a clamp on amp meter on my neighbors pump and saw how much power his was using compared to mine. I was less than 50% of the power for similar flow rates. I hesitate to quote the actual delta because pipes and plumbing are not the same. I feel very safe saying my power consumption is 50% lower than his for similar size pools. Get a clamp on amp meter and see what kind of current you are using now. When you slow down the flow rate the system is extremely efficient both in filtering quality and power consumption.

Back last Summer the 4x160 could be had for about 900.00. If you do not have the Intellitouch system the 4x160 is probably a better option as you loose most of the functionality of the full intelliflo without the intellitouch. I think the 4x160 does 4 settings vs intelliflo which has many. To be honest I could have used only 4 and been just fine.

I was recently asked if I had it to do all over again would I spend so much on the pump? Absolutely, I will recover my additional cost for the pump in a year with the power savings, so why not. The additional cost for the intellitouch system in 2 years. My pump has a 3 year warranty, maybe because I have all Pentair equipment but not sure. I thought the standard came with a 2 yr, but I am not 100% on that either. If you have any more Questions please PM me as I do not come here very often but would be happy to help.

[chem geek]

From what I've read, the IntelliFlow 4x160 has the same efficiency (pump curves and electrical consumption) as the more expensive IntelliFlow in spite of what this comparison says about efficiency savings. Other than some bells and whistles, it comes down to whether you control speed or flow. If you have a filter or other parts of your system that change over time, then controlling for flow is more efficient (and probably accounts for the "up to 90%" number). In my case, I have a cartridge filter that barely registers a 1 PSI increase over each year of use and I clean it every year (my electric opaque pool cover keeps out junk that normally clogs filters much faster). Therefore, for me, the 4x160 looks like the best buy (thank you Big_D for the great advice). I can use the Pentair IntelliComm to connect my already existing solar controller to switch pump speeds at the same time that it switches the existing automated valve to turn on/off the solar. That just leaves the pool sweep pump as something that might be able to be replaced as a 3rd speed plus another automated valve (though the high GPM requirement might not be compatible going through the solar so perhaps a separate bypass pump is still the best way to go). [EDIT] I just saw that I can replace my Letro Legend with a Legend II that does not need a booster pump, so I could probably just have a higher 3rd speed that isn't too high for the solar (max 8 GPM per panel so I could go up to 96 GPM and I'm sure the Letro II won't need that much anyway) and away I go...one more pump to hurl out of the pump house - YEAH! NO! I just called Pentair and the Legend II that claims to not need a booster pump in fact does require 50 PSI pressure (at a low GPM) where they normally recommend a 1.5 HP pump and I can't nor shouldn't put that kind of pressure through the rest of my system. So it looks like a 3/4 HP pool booster pump is required for using a pressure cleaner. Perhaps I should look at a vacuum cleaner instead (Kreepy Krawly, etc.) [END-EDIT]

One more thing I should try doing and that is to lower my turnover rate, at least when the solar is off (because the solar requires a certain flow rate for efficiency and that results in 5.6 hour turnover). I've never done the experiment of reducing pump time until the water starts to get slightly cloudy to see what the minimum turnovers per day really should be. I'll bet I could have the solar off turnover be 8 hours (one turnover per day) with no problems. Ka-ching, ka-ching, I can hear the money being saved already.

I think I'm getting a decent handle on this and I have options. Inexpensively scale down my pump to 3/4 or 1/2 HP depending on energy efficiency ratings or get the Pentair Intelliflow 4x160 and IntelliComm for higher upfront cost, but probably much greater savings. I'm leaning towards the latter, but I'm definitely going to do something because the electricity costs are out of this world and not going to get any better. And I'm getting excited about making the change (always a good sign).

Richard

[Big_D]

Richard,
In my system I am using separate booster for the Legend Platinum cleaner.
If you have a computer control system you should be able to select 4 modes on the 4x160. I have PM'd you on how I would contact Pentair to confirm that.

The inteliflo does show actual flow and RPM, not sure what the 4x160 does.
email me,
Thanks

[mas985]

My understanding of the Intelliflo and the 4x160 is that the Intelliflo allows you to adjust either flow rates or speed (RPM) vs the 4x160 which only allows you to adjust the speed.

The avantage of the flow rate adjustment is that it is independent of head loss so when you turn on the solar or other any other valve changes, even though the head loss changes, the pump will automatically adjust the RPM such that the flow rate remains constant. This allows for a constant turnover rate and thus a constant run time. This is primarily the reason for the difference in energy savings. For the 4x160, you must set the RPMs for the worst case such that some of the time you will be running the pump longer than necessary.

Although the Intelliflo has not been around long enough to determine reliability, if you can afford it, it definitly has some advantages.

[chem geek]

Mark,

So with the 4x160 I would set up two programs, one for solar on that had an RPM that produced a GPM of 48 (that I must calculate from the pump curves and my pressure reading converted to head in feet plus add the estimated suction loss), with the other program for solar off that was set for a worst-case of 8-hour runtime (since that's how long my solar could effectively be used for heating) for 1 turnover which is 16,000/(8*60) = 33 GPM. I would switch between the two automatically based on my existing solar thermostat (which already outputs to a Jandy automatic switch so could also output to the 4x160 via IntelliComm).

With the full IntelliFlow, the "filter" program would be set at 33 GPM while I would have a "feature" for the solar that was set at 48 GPM and would be triggered (via IntelliComm) by the solar thermostat. So my worst-case energy waste with the 4x160 vs. the full IntelliFlow is when the solar is on for a full turnover, so 16,000/(48*60) = 5.5 hours at which point, assuming the water is warm enough (so that the solar shuts off), the Intelliflow shuts off completely for the day. That comes to an energy waste with the 4x160 of (8-5.5) = 2.5 hours running at 33 GPM. This is probably a few hundred watts so about $6 per month or so.

Of course, with the full IntelliFlow I also get the flow meter so don't have to try and estimate (possibly inaccurately) my flow rates using pump curves and the pressure gauge. And it will be more flexible if flow rates change for any other reason.

Whichever way I go, this will really make that booster pump for the Letro Legend really stick out with its wasteful 1470 Watts, even though it doesn't run as often. I can't even use another IntelliFlow 4x170 for this application since it apparently requires 50 PSI (115 feet of head) at 12 GPM. It's really too bad there isn't a more efficient pump for this purpose. I've looked at vacuum cleaners instead, but they vacuum to my filter and not to a bag so that's a hassle for cleaning. I've also looked at automated cleaners (probably the most energy efficient option), but they require a 24V power cord going into the pool which is a separate hassle. About all I can do is to reduce my cleaner run times as much as possible, unless you have some suggestions.

Richard

P.S.
I thought of another reason why the flow-metered IntelliFlow would be better. In my calculations for the solar, I was assuming steady state, but in fact during the priming of the solar an additional 15 feet or so of head is present and that would require a higher RPM to attain (even at a lower GPM -- the curves are somewhat "flat" at constant RPM), but this extra RPM (and energy) would be wasted (and lead to higher flow rates than needed) once priming was completed. Looks like the full IntelliFlow is the way to go for my system.

[mas985]

Mark,

So with the 4x160 I would set up two programs, one for solar on that had an RPM that produced a GPM of 48 (that I must calculate from the pump curves and my pressure reading converted to head in feet plus add the estimated suction loss), with the other program for solar off that was set for a worst-case of 8-hour runtime (since that's how long my solar could effectively be used for heating) for 1 turnover which is 16,000/(8*60) = 33 GPM. I would switch between the two automatically based on my existing solar thermostat (which already outputs to a Jandy automatic switch so could also output to the 4x160 via IntelliComm).

This should work but if you want to have the same flow rate for solar on or off, then use this formula:

RPM solar on = RPM solar off * sqrt (Head Solar on / Head solar off)

This will force the flow rates to be nearly the same and thus the run times to be the same as well and should be just as efficient as the IntelliFlow just a bit more work setting it up.

With the full IntelliFlow, the "filter" program would be set at 33 GPM while I would have a "feature" for the solar that was set at 48 GPM and would be triggered (via IntelliComm) by the solar thermostat. So my worst-case energy waste with the 4x160 vs. the full IntelliFlow is when the solar is on for a full turnover, so 16,000/(48*60) = 5.5 hours at which point, assuming the water is warm enough (so that the solar shuts off), the Intelliflow shuts off completely for the day. That comes to an energy waste with the 4x160 of (8-5.5) = 2.5 hours running at 33 GPM. This is probably a few hundred watts so about $6 per month or so.

With the Intellifow I would just set it for one flow rate and it should automatically adjust for solar on or off to maintain the same flow and thus the same run time.

Of course, with the full IntelliFlow I also get the flow meter so don't have to try and estimate (possibly inaccurately) my flow rates using pump curves and the pressure gauge. And it will be more flexible if flow rates change for any other reason.

Yes, the 4x160 only has four settings which might be enough but the Intelliflow is easier to set up and more flexible for various situations.

Whichever way I go, this will really make that booster pump for the Letro Legend really stick out with its wasteful 1470 Watts, even though it doesn't run as often. I can't even use another IntelliFlow 4x170 for this application since it apparently requires 50 PSI (115 feet of head) at 12 GPM. It's really too bad there isn't a more efficient pump for this purpose. I've looked at vacuum cleaners instead, but they vacuum to my filter and not to a bag so that's a hassle for cleaning.

You can add a leaf trap to the vacuum line which collects the leaves before they enter the pump basket. I have one for mine.

I've also looked at automated cleaners (probably the most energy efficient option), but they require a 24V power cord going into the pool which is a separate hassle. About all I can do is to reduce my cleaner run times as much as possible, unless you have some suggestions.

If I had to do it all over again, I would have gone with a Robotic. The 24v line is much easier to deal with than either a pressure or vacuum line.

Richard

P.S.
I thought of another reason why the flow-metered IntelliFlow would be better. In my calculations for the solar, I was assuming steady state, but in fact during the priming of the solar an additional 15 feet or so of head is present and that would require a higher RPM to attain (even at a lower GPM -- the curves are somewhat "flat" at constant RPM), but this extra RPM (and energy) would be wasted (and lead to higher flow rates than needed) once priming was completed. Looks like the full IntelliFlow is the way to go for my system.

Actually during priming dynamic head builds very slowly as the pipe fills. So when the water gets to the roof, you only have half the dynamic head and as the water falls, you lose the static head and gain the other half of dynamic head.
Net Net, priming total head will be much lower than full flow head. To prove it to yourself, watch your filter PSI as you go from no solar to solar.

See Comments Above.

[chem geek]

Mark,

Thanks again for your wisdom and great advice. Before I got your response, I took a look at the IntelliFlow pump curves and came up with the following formula that tracks very, very well with the curves:

Head = (RPM/350)^2 - (GPM^2)/470

This essentially reduces to the formula you gave, if comparing two different Head/RPM combinations, assuming that the GPM is 0. The above is more accurate when there is a non-zero GPM, but because the curves are relatively flat this isn't a huge difference at low GPM.

For the 4x160, I intentionally wanted to use different flow rates for solar on and off since the solar on required 48 GPM for its solar panel efficiency while the solar off had no such requirement so could use a lower GPM of 33 worst-case (i.e. 8-hours) and this lower GPM (and RPM) should result in lower power and energy cost. This assumed that I always ran the pump for 8 hours since that is how long the solar could effectively be used to heat the pool. I understand that a single flow rate is simpler, but it's also (somewhat) more expensive.

For the full IntelliFlow, I can see how setting a single flow rate is easy (and I wouldn't need the IntelliComm in that case) and that the IntelliFlow can cut the runtime to only do a single turnover, but there could be a case where it goes for 5.5 hours without the solar and then turns off (because that's one turnover with the 48 GPM rate that I must have to make the solar efficient in case it comes on), but then the sun comes out and there won't be any solar heating because the pump is off. That's why I wanted to hook in to the solar as a "feature" to be able to force the pump on. So while I had two situations anyway (solar on and solar off), I figured to minimize the energy usage in the most extreme cases with two different GPM rates.

I understand the simplicity of a single flow rate, but thought I'd get away with lower flow in the solar off times because, well, because I can. In fact, I don't have to limit myself to 8 hours in that case and can have the pump "enabled" for the full 24 hours since I know the solar won't get triggered except during the day while the pump could use a VERY low GPM over up to 24 hours until one turnover is achieved. What I don't know (yet) is at what point a low GPM becomes less energy efficient where the longer time takes more energy than is saved by the lower GPM (and lower frictional losses). I don't have a good formula for the "power" curves except that it's about 50% of output power (proportional to product of GPM and Head) above about 40 GPM at low RPM and above 80 GPM at the highest RPM (at very low RPM, efficiency goes to hell regardless of GPM -- probably due to electrical and motor efficiency losses, so clearly using a very low GPM does not make much sense).

A leaf trap to the vacuum line -- BRILLIANT! Jeez, I wish I had thought of that, but am glad you did. It seems that the requirements for a vacuum unit are much less stringent (it would appear that they require 25 GPM) and I could probably then have an automatic valve switch to use the vacuum cleaner on suction (instead of the skimmer) and the flow rate could be set to whatever is needed for that feature (hopefully, the same 48 GPM that the solar uses would be sufficient, though this is cut down due to sharing the suction with the floor drains which are on a separate line until we get close to the pump; also, the line to the cleaner is 1.5" instead of 2" so the losses will be greater than on the floor drain line). If I wanted to figure out approximate flow rates for these two lines that are branched together at the suction side of the pump, how do I do that? I can estimate friction losses from the pipe, but how do I know what losses or restrictions there are at the floor drains and skimmer? I know that the negative pressure at the pump side must be the same between the two lines (though their GPM will clearly be different due to different line sizes) and can calculate the less negative pressure as I move through the line, but do I just assume no resistance at the opening to the pool and just assume the flow rates are related to the size of the line (i.e. assume the suction loss is the same in both lines and work backwards to calculate the GPM in each line that would make that happen)?

In terms of using a robotic cleaner, I don't think I can get away with having a cord on our hardscape to go into the pool -- my wife is picky about those things. And removing the robot might be more of a pain, though maybe it's about the same as pulling out the pressure (or vacuum) cleaner -- right now we just put the line that was in the pool over onto our coping and keep the sweeper unit in the corner at the deep end while we use the pool. What problems do you have with your vacuum cleaner or using a vacuum line?

Thanks for the explanation of priming. That makes perfect sense to me.

I feel like breaking out singing, "I'm so excited....and I just can't hide it....I know, I know, I know, I know, I know I want IntelliFlo...I want IntelliFlo". OK, so my rhythm sucks.

Richard