Am I Interpreting Pump GPM RPM and Watts Numbers Correctly?

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KatyTXPoolOwner

KatyTXPoolOwner

0
Jul 18, 2015
104
Katy TX
I am trying to figure out if I am interpreting the data from my main pump correctly, with the ultimate goal of running the main pump as cost effectively while maintaining a well-filtered and clean pool.

Here's what I see on the display when I check "Status":
GPM 35
RPM 1580
Watts 326

Local electric rate is $.06/kWh

Current Main Pump Run Schedule:
I run the pump 15 hours a day (7:00am - 8:00pm and 12:30am - 2:30am daily), which should turn approximately 31500 gallons everyday.

The way I calculate it (see below), the above information puts me at $9.10 total for 31 days, which seems a little hard to believe (I think it would cost more).

$.06 kWh rate
x .326 kWh used (326 Watts from Pump display)
x 15 hours a day
x 31 days a month
= $9.10 electricity cost to run main pump only for 15 hours a day for 31 days a month

Is my approach correct? If not, can someone point me to a more accurate calculator?

Thank you!
 
326 W seems small...what is the voltage and amperage rating for your pump? What is the brand? A 5 amp, 220V pump consumes an instantaneous power demand of 1,100W, or 1.1 kW (220 x 5). Running this pump for 1 hr will consume 1.1 kWh of electricity. Running it for 2 hours, will draw 2.2 kWh of energy, and so on.




68,000litre, IG vinyl, LorentzPS 600 Solar Pump & 1/2 HP Tristar, Sandfilter, Aquarite T-15 SWG
 
Well then something is wrong with your readout. If The pump is consuming 326 W, and is wired for 230V, then it is only consuming 1.4 amps (326/230). That seems very low....

Operating at full load (16 amps), then the pump consumes 3,680W, or 3.68 kW. Operating at this load for 15 hours, yields a total energy draw of 55.2 kWh, costing you $3.31/day or $100/month.




68,000litre, IG vinyl, LorentzPS 600 Solar Pump & 1/2 HP Tristar, Sandfilter, Aquarite T-15 SWG
 
Katy......r,

If you want your electric bill to be higher, I'll gladly send you mine.. :D

You have discovered the wonder of having a VS/VF pump. The "full load amps" figure is meaningless unless your were running the thing at full speed. My VS Intelliflo only uses 172 watts at 1200 RPM where I run it most of the time.

Your numbers look correct to me.

Jim R.
 
Anybody else out there able to support me and Jimrahbe?

If so, I guess I'm REALLY happy to have told my builder to put in the Pentair IntelliFlo Variable Flow pump. Hard to beat less than $10/month when it's running 15 hours every day.


Sent from my iPhone using Tapatalk
 
Just make sure that you have good surge protection for the pump. If you have to replace the pump at $1,000 due to a surge, all your savings goes away. The pump is a high powered motor controlled by an onboard computer, and is very sensitive to surges and power spikes.

I actually have two "whole house" type surge protectors. A larger one on my main service panel that protects all my electronics, and a smaller one on my pool sub panel for additional protection on the pump and other pool equipment. About $150 and one afternoon well spent.
 

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KatyTXPoolOwner said:
Anybody else out there able to support me and Jimrahbe?

If so, I guess I'm REALLY happy to have told my builder to put in the Pentair IntelliFlo Variable Flow pump. Hard to beat less than $10/month when it's running 15 hours every day.


Sent from my iPhone using Tapatalk
Click to expand...

I agree that VS pumps can save a lot of money if used properly and in a high utility rate area of the country. If a person is doing a new build, a variable speed pump is almost always the best choice because the incremental cost of the equipment is tiny compared to the overall build cost. For people with existing pools, the high entry cost of a VS pump can make it an unattractive option as a low utility rate means one will never really recoup in savings the original capital outlay. In many cases, for an existing pool installation, just simply swapping out a single-speed motor (and impeller) with a properly sized 2-speed motor will still save a lot of money and allow one to recoup the cost of the new motor very quickly.

The only issue I take with your setup is that you spent extra money on the variable flow pump instead of just using the variable speed pump. Being able to precisely dial in flow rates is really totally unnecessary as the concept of having a specific number of turn-overs per day is an old concept that has no real meaning. Pump studies have shown that people can't tell the difference between a pool that has had a lot of turnovers per day versus one or two turnovers. What matters to a pool is water quality and filtration and that is typically satisfied with only a few hours of pump time. Also, if one has the pumping curve and power output from a VS pump as well as the RPM's and system pressure, it's a fairly simple calculation to look up the flow rate of the system therefore it's not even necessary to have a fancy flow meter installed into the plumbing. SO you paid a little extra for the VF option which, I admit, is neat but it is is not necessary. Also, when you set a specific flow rate on the pump, the pump is going to vary the RPM's to get the desired GPMs. This means your actual power level is going to rise as the filter load increases so you can't assume that it is going to be the same number of watts everyday.

It's all no big deal but I would have ditched the VF option just to save some money.
 
KatyTXPoolOwner said:
The Max GPM for the pump is 130. I have it set for 35 GPM, which is 26.9% (35/130) of the maximum. Is it correct to look at it that way?
Click to expand...
No. 130 GPM is run out. The pump will never achieve that.

You need to know your plumbing curve. Typical 2" plumbing will have a max flow rate of about 100 GPM, 1 1/2" plumbing, the max flow rate drops to about 73 GPM. But your results may vary.
 
It is true how little power these vs pumps use. they say that they are most efficient at about 800 rpm. you might be able to save a bit more if you run 24 hrs at lower speed. you still need to make sure its turning the pool the amount you want though. I run at 2800(I think) for 2hr and 800 the rest. I do the 2800 for my vacuum but it looks like you don't have one based on the lower rpms for 15hr
 
sorry I just always use the term turnover from my aquarium days. pool school recommends 8hrs if you can run on lower speed and more if you feel its needed. I was thinking the amount of time the pump was running is whats needed for that pool. Only pointing out it could maybe run the same volume of water for less money.
mas985 said:
You will save 6x more with 4 hrs.


Turnover is irrelevant. Please read pool school: Pool School - Determine Pump Run Time
Click to expand...
 

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