Single, Two or Variable speed pump

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D

dubele

0
Jun 17, 2013
157
Southeast Pennsylvania
Hello all,

Almost getting ready to dig the pool. Sorry if I posted something similar to this before. I have around a 400 s.f. pool going in and it will have 2, maybe 3 sheer descents. They have me spec'd out with a Jandy 2 H.P. pump. I told the guy I thought that was way too big. He agreed and said it would be it you didn't have the sheer descents.

I asked if it would be better to go with a booster pump for the sheer descents and go down to 1 or 1 1/2 H.P.? He said no.

My main concern is mostly consuming too much electricity. My lesser concern, but still a concern is having to turn the pump on to run the falls.

I asked the guy, "If this was your pool, what would you do". He said, "I'd go with a 2 H.P. variable speed pump. You can adjust them and save electricity and the extra cost will be saved in two years."

Is this good advise?

Thanks,
Doug

P.S. - For what it's worth...I've dealt with many different pool builders and people and have developed, I think, "radar" for not being told the truth or for "slimey" sales pitches. Maybe it isn't accurate, but I felt this guy was truthful. On another topic, minerals, I told him I read over and over (and mostly from here) that I haven't read ONE good thing about minerals, but you guys are pushing it on me.....He said, "I would NOT go with minerals....I'd go with salt". So, he seemed honest...and, plus, he said this in front of the salesman and a VP for the company....and they kind of had a look of..."Would you shut up!!!"
 
I'm just now starting to research this stuff, so right off the bat I'm going to tell you to keep watching for an EXPERT to post up.

What I've seen is that if you install an automation system, you can program a VS or VF pump to run at low speed for circulation, bump it up for a couple of hours per day for your skimmer(s), then manually or automatically have it bump to whatever is needed when features are on.

There are ways to set up manual triggers, for example you want to use the descents while swimming, you hit a button and those valves come open and the pump cranks up. You can even set them to run for "X" hours so that you don't have to remember to turn them off at the end of your party.

Same goes for any backflushing or vacuuming you may need to do. You have the ability to set the flow or speed to fit your needs.

I'll even say you probably don't want those features on unless you are using your pool area. A lot of those features are bad about causing your pH to rise. So being able to keep them off will prevent that problem.

Again, please wait for an expert, but this is what I've been reading up to now. In fact, I'm going to follow this thread so I can learn along with you.
 
I put the following comparison in the Hydraulics 101 sticky. It basically shows life cycle cost for various pumps. It comes down to how much you pay for electricity, the cost of the pump and run time. You can also download your own version for customization here: hydraulics-101-have-you-lost-your-head-t915.html#p6544


PumpEnergyCosts10.jpg
 
I am glad you brought that up. I'm considering the savings of VF over 2 speed to be zero. I did not purchase a VF to save any more than a 2 speed. It might actually save some, but I did not want it to sway my decision.
 
Me? I got a sales pitch on the VS a long time ago. I decided on the VF on my own. It is probably overkill for what I have now - ok I KNOW it's overkill for what I have now - but since I have to replace my 22 year old pump, I decided to go overboard because we have plans for the future.
 
dubele said:
Thank you for the information. That's a lot of numbers and I am not sure how to apply to my situation. In your opinion, did I get a sales pitch or good advise?
Click to expand...
It depends.

What do you pay for electricity $/kwh ?

Which VS are you considering? Some cost much more than others.

The bottom line is a VS can be more cost effective and allow for more flexibility in setting flow rates so it can be a good option. For a new pool, where you are spending big bucks, it usually makes sense because the upgrade cost is small compared to the cost of the pool.
 
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?

EDIT====> I just called Zodiac. Jandy has two variable speed pumps, the E-Pump and the VS Flo Pro. Both of these are 2,400 watts. Is this at the highest level?? Crud...I guess I should have asked him what the watts are at the lowest?.....as I he said I would run this for 12 hours at the lowest setting.
 
Dubele,

I've had a variable speed pump for some time and the payback over a two speed depends on lots of factors.
These pumps magnets usually get you a baseline 20% increase over a standard pump- but the brochures talk about 90% savings.
You can rarely achieve this.

The single largest factor bumping the 90% numbers is that each pool has a minimum speed at which the pool actually function regardless of how slow the pump can run.

Each pools "ecosystem" is unique - The amount of 45 and 90 degree bends you have, the head pressure, the plumbing size, the length of the pipe runs, and filter pressure, heater min flow rate , SWG flow rate, effective skimming- all contribute to what the minimum speed is. Architecting a pool in such a way to minimize pressure and flow restrictions will pay off in the long run.

The test stand cases have 10 feet of pipe, no traps, no SWG, no heater,and usually no filter - not realistic.

If you put a SWG in its going to want to see something like 25-30 GPM or up or it wont activate so this become the minimum speed at which you can actually run your pump regardless of how slow its capable of turning.

Its these variables that decide whether a variable speed pump will payback quicker than a 2 speed (payback over any baseline increase)

IF you turn so little RPM you have no skimming action - and you have to crank it up to 1/2 HP to make everything work then you mights as well stick with a 2 speed pump and spending the money on a variable speed pump wont give you the ROI you are looking for or the ROI will be far less than what you would hope.

If you look at the purchase as a flexibility and performance upgrade you will be happier than if you simply view it as a "savings" purchase.

My thoughts and experience.

Thanks

Uncle Dave
 
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?

EDIT====> I just called Zodiac. Jandy has two variable speed pumps, the E-Pump and the VS Flo Pro. Both of these are 2,400 watts. Is this at the highest level?? Crud...I guess I should have asked him what the watts are at the lowest?.....as I he said I would run this for 12 hours at the lowest setting.
Click to expand...

Pumps usually are rated in HP but 1 HP =746 watts so you can figure it out pretty easy.

What they "say" and what you actually pay are like when you sign up for a cell phone contract where the 50 per month bill is actually 239 a month after all the BS they tack on.

In many areas the quoted rate is low then a billing scale is applied as you consume more.

IF you using the "stated" charge on the bill x KWH you get one number
When you divide the KWH hours into the total bill amount you get a vastly diff number.

I find mine goes from 12.5 to about 16 cents when I actually look at what I pay vs. what the company states it is.


Thanks!

UD
 

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Ok....Thanks everyone. This was helpful. It sounds like there is no clear "concrete" choice. I will go with a variable speed and hope for the best. Kinda regretting putting this pool in.....I hate not being able to make decisions that I am not 100% certain about. I suppose I will gain knowledge on my pool and know what to do once experienced. Please don't take those comments in an insulting way.....this whole process of putting the pool in has me exhausted.....and they haven't even starting to dig yet! Really, thanks for your input!
 
Davegvg said:
Pumps usually are rated in HP but 1 HP =746 watts so you can figure it out pretty easy.
Click to expand...
It isn't that simple.

First, the motor label HP isn't even the actual total HP rating of the motor. That is determined by the product of the label HP times the service factor.

Second, you need to take into account the motor efficiency which for the Jandy E-Pump is around 87%.

Third, you need to take into account the operating point of the pump. Higher head loss results in lower energy use (and flow rate).

Fourth, for a VS, you also need to take into account the speed of the motor.

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
 
Here's one nice thing about a VS pump. With my VS pump, at some speeds it causes a resonant vibration in the other pool equipment - in particular the heatpump. But by just tweaking the speed a few rpm up or down I can eliminate it and get very quiet operation. With a 2 speed pump, as long as those speeds don't cause that resonant vibration with other equipment, you'll be fine, but you'll never know this until you install it.
 
mas985 said:
Davegvg said:
Pumps usually are rated in HP but 1 HP =746 watts so you can figure it out pretty easy.
Click to expand...
It isn't that simple.

First, the motor label HP isn't even the actual total HP rating of the motor. That is determined by the product of the label HP times the service factor.

Second, you need to take into account the motor efficiency which for the Jandy E-Pump is around 87%.

Third, you need to take into account the operating point of the pump. Higher head loss results in lower energy use (and flow rate).

Fourth, for a VS, you also need to take into account the speed of the motor.

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...

Do we agree pool pumps arent measured in amps?

Usually it isnt that simple - but it can be.

Sometimes the label actually IS the total rating if there is no service factor applied.

If there is no service factor and the pump is 1HP it should not pull more than 746 watts.

Are you saying a 1HP pump with no service factor added changes its power consumption based on its efficiency?
How much wattage would a 1hp pump with no service factor and .87 % efficiency be computed? Are you saying this pump will consume 13% more wattage than a 1HP pump or are you just calling out that it will flow 13% less than a 1HP pump with 100% efficiency (if such a thing existing)

GPM will vary on each pools setup at any given RPM.

Pretty sure I talked about VS using variable wattage in my post above even if I didn't explicitly call it out.




UD
 
gatorbrit said:
Here's one nice thing about a VS pump. With my VS pump, at some speeds it causes a resonant vibration in the other pool equipment - in particular the heatpump. But by just tweaking the speed a few rpm up or down I can eliminate it and get very quiet operation. With a 2 speed pump, as long as those speeds don't cause that resonant vibration with other equipment, you'll be fine, but you'll never know this until you install it.
Click to expand...


Thats a super interesting point and that rises a question for another thread of how one would fix a harmonic in a fixed system?
(guess with pipe length change )

If you could vary the RPM quick enough you could play a song with a vs pump.


UD
 
Davegvg said:
If there is no service factor and the pump is 1HP it should not pull more than 746 watts.
Click to expand...
That would only be true if the motor is 100% efficient which it is not.

Davegvg said:
Are you saying a 1HP pump with no service factor added changes its power consumption based on its efficiency?
Click to expand...
Yes. Two different 1 THP motors with different efficiency will draw different power.

A motor label HP label times service factor (THP) is the maximum OUTPUT power of the motor (i.e. shaft power) which is not the same as the electrical input power of the motor. The ratio of THP divided by EHP (electrical HP) is the motor efficiency.

So THP <> EHP and if a 1 THP motor has a 87% efficiency AND it is fully loaded (most pool pumps are not fully loaded), then the motor will draw

1 HP * 746 watts/hp / 0.87 = 857.47 watts

But again, it is important to remember than motor labels are ratings which specify maximum operating points and not actual operating points.

Here is a good reference to motor label terms:

Motor Nameplate Definitions

Nameplate HP (NPHP) - This is the HP rating on the motor nameplate but is pretty much meaningless without the service factor.

Full Rated HP (FRHP) - Similar to nameplate HP and sometimes used when the pump is full rated.

Up Rated HP (URHP) - Similar to nameplate HP and sometimes used when the pump is max rated or up rated.

Nameplate KW = NPHP * 0.7457 - This is the KW rating and is similar to the nameplate HP and is generally used outside the US. Note that this is not the input power to the motor only the rating for the output power of the motor.

Service Factor - This is an overload rating for motors which states that the motor can be safely operated over the NPHP by the service factor for short periods of time. However, for pumps, this overload rating is typically used as the maximum load that a motor would need to deliver to the wet end. Because the load on a pump does not rapidly change over time, the service factor load is often used as the maximum design point for the pump.

Total HP (THP) or Service Factor HP (SFHP) = NPHP * Service Factor. This is the maximum load that can be safely driven by the motor and must always be greater than the maximum load from the impeller. A motor can be driven above the THP but will likely fail in a short period of time.

Electrical Horsepower (EHP) = Input Watts / 745.7 = Volts * Amps * Power Factor / 745.7 - Electrical power input delivered to the motor.

Brake Horsepower (BHP) = EHP * Motor Efficiency - Power delivered by the motor shaft to the impeller. This is not the same as THP or SFHP. BHP is a function of the load on the motor shaft and will change with Head, GPM and RPM.

Hydraulic HP (HHP) = BHP * Pumping Efficiency = Head (ft) * GPM / 3960 - Power delivered to the water. Sometimes called water HP (WHP) or pumping HP (PHP).

Motor Power Efficiency = BHP / EHP - I2R, magnetic and mechanical losses in the motor only.

Pumping Power Efficiency = HHP / BHP - Recirculation and internal friction losses in the wet end only.

Total Pump Power Efficiency = Motor Efficiency * Pumping Efficiency = HHP / EHP (note this is why total pump efficiency approaches 50%).

Energy Factor - Gallons/watt-hr = GPM * 60 / Watt-hr; A CEC definition used to measure a pump's true pumping efficiency.

Service Factor Amps - The amp draw when the motor is loaded to the service factor. Also, multiplying the SF amps by voltage should also give a good estimate as to the upper limit for power draw. However, sometimes the motor is over dimensioned for the pump so it will not always be an accurate measure of input power.

Full Load Amps - This can mean several things depending on the motor manufacture. It is either the amps at the NPHP or it can be the amps at the THP. I have seen it both ways so unfortunately, there is not a good standard for this one.
Click to expand...
 
Great chart hadnt heard of some of those terms- but I'm not surprised given your solar info.

1 HP * 746 watts/hp / 0.87 = 857.47 watts - if the pump is fully loaded.

What is the effect on this number with an 80% 90% loaded pump?

- are we just taking 10%-20% off the net wattage of the above formula or does the pump load compute another way?

Thanks!

UD
 

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