Single, Two or Variable speed pump

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Motor loading efficiency is a bit more complex to determine but it follows a quadratic curve. It stays fairly constant until the load gets below 50% and then it starts to drop off. Also, the pump imparts a peak load to the motor around the best efficiency point (BEP) and load decreases on both sides although to left of BEP on the head curve, load decreases faster than the right side of the head curve.

Although, the actual loading on the motor vs the head curve is not easily obtainable, there are parameters that are known like input power from the CEC/APSP pump data set and HHP (hydraulic HP) from the pump's head curve. For example, for the JEP 1.5 VS pump at various plumbing curves, you can get an idea of how loading changes.

BEP - 3450 RPM, 115 GPM, 2158 Watts, 3.2 EF, 1.62 HHP, 2.89 EHP, 56% Total Efficiency
Curve C - 3450 RPM, 90 GPM, 2016 Watts, 2.7 EF, 1.52 HHP, 2.70 EHP, 56% Total Efficiency
Curve A - 3450 RPM, 67 GPM, 1729 Watts, 2.3 EF, 1.25 HHP, 2.31 EHP, 54% Total Efficiency
Curve B - 3450 RPM, 40 GPM, 1395 Watts, 1.7 EF, 0.81 HHP, 1.87 EHP, 43% Total Efficiency

Unfortunately, BHP (motor loading) is unknown because we do not have the motor efficiency or pumping efficiency vs the head curve. We only know that the maximum motor efficiency at full load is 87% which should be close to the BEP. You could assume that the motor efficiency stays fairly constant over that range and then estimate BHP based on that. BHP ~ EHP * 0.87. But there would be some error involved with that method.
 
I'm going to borrow a clamp on ammeter and see what it says when I rpm up to 750 watts indicated - curious if the readout compensates for the variables.
My old pentair pulled pretty close to 750 watts..on a fluke multmeter

UD
 
How do we answer the posters question?

Is the answer really that he should even try to use a HP watt number? x whatever he pays per KW hour?

If 1Hp isn't really 746 watts because of various efficiency factors and you cant use that to determine run costs...

What is the answer?

Should the poster go through a mathematical formula when trying to figure out how much a 1 HP or a 3/4 HP pump will cost to run ?

I also wonder what formula is "close enough" given there is so much one never knows about a given pools flow and pump loaded etc to use?



Uncle Dave
 
mas985 said:
So for the pump's mentioned and assuming typical 2" plumbing, here are a few operating points for each pump.

JEP 1.5 @ 3450 RPM - 90 GPM @ 1966 Watts
JEP 1.5 @ 1725 RPM - 45 GPM @ 332 Watts

VS-FHP2.0 @ 3450 RPM - 89 GPM @ 2103 Watts
VS-FHP2.0 @ 1725 RPM - 44 GPM @ 333 Watts
Click to expand...
I thought I already answered the question. There is very little difference between the two pumps. I would go by price and features.

But you should never attempt to calculate watts from HP. That almost never works. There are measured data in the CEC/APSP database that are much more reliable and that I use in the pump cost comparison spreadsheet (see signature).

The bottom line is that the brand/size of VS pump really doesn't make a huge difference in run time costs. What really drives run time costs is the flow rate. Low flow rates are efficient, high flow rates are not. There is a slight edge for VS pumps over 2 speed pumps but there again, not by much.
 
dubele said:
I just called my power company. They charge me about 12.5 cents per kwh. As far as what pump, all I know is they deal with Jandy. I will try and find out what the model is. What do I need to determine cost once I know the model number?....do the pumps list watts or amps?
.
Click to expand...


This was the question I was trying to answer.

If he just goes and buys a 1HP pump vs. a 2 or VS pump - what number would he use ?


UD
 
I Know Nothing said:
Thanks for the Motor Nameplate definitions! And thank you, Davegvg, for promoting it. lol
Click to expand...


Pump is in my sig line.

Not promoting anything but the reading.

I actually dont like this pump as much as my pentair.

I posted a link to a video earlier where I talked about it being annoyingly large.

- added later- I also thinks its the loudest of the VS pumps - the only reason I didn't use a Pentair VS is because of my control system.
I also don't particularly like the AO Smith brand.

Im just trying to figure out how to reconcile the data I collect in the field with the data posted- and

I also think Mark is likely the smartest guy about all this stuff, a great resource to the forum, and Ive really learned a lot from him just in the solar forums.

UD
 
Davegvg said:
At 3450 RPM my remote told me I was consuming 1628 watts.
Click to expand...
But that is pretty low power for a JEP 2.0 which means you must have pretty high head loss. What was the filter pressure at that setting? What is the size of your plumbing?

Also the JEP 2.0 is not more efficient than the FHP 2.0, they are about the same. The difference in power is due to the difference in plumbing. Your plumbing must be high head loss.

When comparing pumps and operating point, you really need to compare energy factors (EF=GPM*60/watts). It is likely that although your pump is drawing less power, it is also producing much less flow rate so the energy factor is lower.
 

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mas985 said:
Davegvg said:
At 3450 RPM my remote told me I was consuming 1628 watts.
Click to expand...
But that is pretty low power for a JEP 2.0 which means you must have pretty high head loss. What was the filter pressure at that setting? What is the size of your plumbing?

Also the JEP 2.0 is not more efficient than the FHP 2.0, they are about the same. The difference in power is due to the difference in plumbing. Your plumbing must be high head loss.

When comparing pumps and operating point, you really need to compare energy factors (EF=GPM*60/watts). It is likely that although your pump is drawing less power, it is also producing much less flow rate so the energy factor is lower.
Click to expand...


Pressure was 22LB
Plumbing 2" all through Except skimmer cuff in the return that chokes it down a bit.
(I could pull that and test again)
Service factor in this pump 1.35

I run the pool at 100 Watts 2`150 RPM and 3lb of pressure 19x7 and 1000 watts when solar tap is open.

Like I said Im not remotely enamored with this pump.

UD
 
There must be something severely restricting the plumbing on the suction side of the pump in order for the power to be that low. Or it could be a partially clogged impeller.

Here is a comparison of all three pumps on three different plumbing curves. Your power indicates that your plumbing is close to Curve-B which is highly restrictive plumbing.

Plumbing Curve-C

JEP 1.5 @ 3450 RPM - 90 GPM @ 1966 Watts EF=2.74
JEP 1.5 @ 1725 RPM - 45 GPM @ 332 Watts EF=8.05

JEP 2.0 @ 3450 RPM - 93 GPM @ 2191 Watts EF=2.54
JEP 2.0 @ 1725 RPM - 46 GPM @ 338 Watts EF=8.21

VS-FHP2.0 @ 3450 RPM - 89 GPM @ 2103 Watts EF=2.54
VS-FHP2.0 @ 1725 RPM - 44 GPM @ 333 Watts EF=7.95
Click to expand...

Plumbing Curve-A

JEP 1.5 @ 3450 RPM - 67 GPM @ 1729 Watts EF=2.31
JEP 1.5 @ 1725 RPM - 33 GPM @ 204 Watts EF=6.55

JEP 2.0 @ 3450 RPM - 69 GPM @ 1933 Watts EF=2.13
JEP 2.0 @ 1725 RPM - 34 GPM @ 331 Watts EF=6.62

VS-FHP2.0 @ 3450 RPM - 66 GPM @ 1907 Watts EF=2.09
VS-FHP2.0 @ 1725 RPM - 33 GPM @ 313 Watts EF=6.34
Click to expand...

Plumbing Curve-B (very restrictive plumbing)

JEP 1.5 @ 3450 RPM - 40 GPM @ 1395 Watts EF=1.71
JEP 1.5 @ 1725 RPM - 20 GPM @ 263 Watts EF=4.54

JEP 2.0 @ 3450 RPM - 41 GPM @ 1556 Watts EF=1.58
JEP 2.0 @ 1725 RPM - 20 GPM @ 267 Watts EF=4.57

VS-FHP2.0 @ 3450 RPM - 40 GPM @ 1638 Watts EF=1.47
VS-FHP2.0 @ 1725 RPM - 20 GPM @ 282 Watts EF=4.26
Click to expand...
 
When I plugged the bottom cleaner in I got 1860 watts or very close to "A".

How can introducing a restriction equate to an improvement in performance?

It would seem that the lower the wattage at the higher RPM would mean greater efficiency in the system than less.



UD
 
Generally speaking, the lower the flow rate, the longer the pump needs to run in order to keep the pool clean so run time is different for the two plumbing curves and needs to be taken into account when assessing energy efficiency. So the CEC developed a methodology for comparing pumps by using energy factors (Gallons/watt-hr) and not just by using watts. In other words, how much flow rate is produced for a given wattage.

So for example, your pump on Curve-B has an energy factor of 1.58 @ 3450 RPM while on Curve-A it has an energy factor of 2.13 so the pump on Curve-A is more efficient even though the pump draws more power because it is also produces a lot more flow rate (69 GPM vs 41 GPM). So while a pump on Curve-B uses less watts, it takes much longer (59%) to turnover the pool and so it will end up using more watt-hrs per turnover than Curve-A.

However, if your run the pump for the same amount of time on each plumbing, then the pump on Curve-B will consume less power but it won't filter as much water either so there is a downside to doing that.
 
mas985 said:
Generally speaking, the lower the flow rate, the longer the pump needs to run in order to keep the pool clean so run time is different for the two plumbing curves and needs to be taken into account when assessing energy efficiency. So the CEC developed a methodology for comparing pumps by using energy factors (Gallons/watt-hr) and not just by using watts. In other words, how much flow rate is produced for a given wattage.

So for example, your pump on Curve-B has an energy factor of 1.58 @ 3450 RPM while on Curve-A it has an energy factor of 2.13 so the pump on Curve-A is more efficient even though the pump draws more power because it is also produces a lot more flow rate (69 GPM vs 41 GPM). So while a pump on Curve-B uses less watts, it takes much longer (59%) to turnover the pool and so it will end up using more watt-hrs per turnover than Curve-A.

However, if your run the pump for the same amount of time on each plumbing, then the pump on Curve-B will consume less power but it won't filter as much water either so there is a downside to doing that.
Click to expand...


I have a blue and White flowmeter- the part that floats up and down you use to read GPM has vanished- gone.

I need to figure out what the flow is. (one more reasons why the VF is super cool)

UD
 
I had the pentair intelliflo vs motor installed. I have a negative edge on my pool. The pump had four preset speeds. Any speed lower than three was not powerful enough to push water over the edge. The spillway was nearly dry. I was told to run on speed two during the winter. I did a test on speed two the spillway was completely dry. So the net effect was I would not be able to use any of the cost saving lower speeds. Since it was twice the cost of the single speed I had them change it out. My electricity rate is 10.9 per kwh
 
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