Variable speed vs single speed pump

[datadr93]

Installing our first pool. So many opinions and no 2 are the same... Especially when comparing owners to what pool company says.

We got a 16x35 fiberglass. Opted for SWG vs chlorine. Approx 11.4k gallons. They provided us a Jandry FloPro 1hp pump. Told us with size of our pool we'd want to run continuously and let the SWG determine salt dispersion.

Other owners (and forums) give inclination we should be using a variable speed pump so can run maintenance modes and not need to run continuously.

Need help if we should have them replace the pump with variable speed.

 

[HermanTX]

The pool builder is most likely recommending the 1hp single speed pump because they have it in inventory and the rules say anything over 1hp has to be a VS pump for filtration use.
In general, you would get more energy savings by running a 1.5hp or higher VS pump at a low speed for a longer length of time. Since you have a SWCG then the preferred pump for that is a variable speed because you can select the lowest pump speed that activates the SWCG and then decide how long you want to run the pump at what % output of the SWCG.

 

[mknauss]

With a heat pump I would suggest the best option is a full size VS pump. The restriction of the heat pump significantly reduces flow. Or be sure to get a bypass for the heat pump installed.

 

[HermanTX]

Here is a curve of a typical VS pump. You will note that the lower the speed the less energy used. Also that it is not linear so the lower speeds really do save money.

 

[datadr93]

Thanks everyone. I'll discuss when they're onsite today.

 

[Jimrahbe]

93,

It sounds like you think running 24/7 is a bad idea, when the opposite is true.. Running 24/7 is not required, but many people do it, as it has several advantages when you have a SWCG.

When running 24/7 at a low RPM, the system will be making a little chlorine all the time. The skimmers will be working all the time, and I think most people like the look of their pool when there is a little motion to the water.

Large 3 HP VS pumps are very economical to run at low RPMs. I have an old VS pump, and it costs me less than $20 a month. Newer VS pumps are much more energy efficient and cost even less to run.

Large VS pumps can move more water at lower RPMs, so they are very quiet. In my case, I almost have to touch my pump to make sure it is still running.

Thanks,

Jim R.

 

[jgofnj]

93,

It sounds like you think running 24/7 is a bad idea, when the opposite is true.. Running 24/7 is not required, but many people do it, as it has several advantages when you have a SWCG.

When running 24/7 at a low RPM, the system will be making a little chlorine all the time. The skimmers will be working all the time, and I think most people like the look of their pool when there is a little motion to the water.

Large 3 HP VS pumps are very economical to run at low RPMs. I have an old VS pump, and it costs me less than $20 a month. Newer VS pumps are much more energy efficient and cost even less to run.

Large VS pumps can move more water at lower RPMs, so they are very quiet. In my case, I almost have to touch my pump to make sure it is still running.

Thanks,

Jim R.

For a large VS pump (3HP) do you need a 2 inch pipe to take advantage of the benefits? Will you get the same benefits with 1.5 inch pipes ?

 

[Jimrahbe]

For a large VS pump (3HP) do you need a 2 inch pipe to take advantage of the benefits? Will you get the same benefits with 1.5 inch pipes ?

j,

Yep.. At low RPMs the pipe size, or the filter size, or your shoes size, does not really matter much...

I have two rent house pools, with 3 HP IntelliFlo pumps, that both have 1.5" plumbing.. They have been running 24/7, mostly at 1200 RPM, for well over 10 years.. I love them..

Thanks,

Jim R.

 

[datadr93]

Issue is they want to provide us with a 1hp single speed pump. I think we're opting for the 1.65hp VS... so we can run 18 hours low/maint RPM and 6 hours at higher RPM. Run longer at times we're having friends/family over. But I don't think 24 hours at 3450 RPM is needed... excessive in fact... and either have on or off which we prefer having some circulation at all times.

Salesperson's exact words were with our size pool (11.4k gallons) we'll want to run it constantly at 3450 RPM. I'm reading and researching that's not entirely true and I feel like a ploy to get rid of stock.

 

[tommelton]

That is roughly the size of my pool, you can check my pool information below in my signature. I run the pump from 7am-noon on low (30% - 1035rpm), noon-6pm on medium (50% - 1725rpm) and 6-8pm on low (30% - 1035rpm). Don't need to run it that long, but I do because the wife likes to see a little movement in the pool.

Typically the only time I run it on high (100% - 3450rpm) is when we run the slide.

 

[HermanTX]

Salesperson's exact words were with our size pool (11.4k gallons) we'll want to run it constantly at 3450 RPM. I'm reading and researching that's not entirely true and I feel like a ploy to get rid of stock.

That is old school thinking because all pumps used be single speed.
My prime speed is not even 3450rpm. I lowered it because my pump is basically level with the pool water level.
Furthermore a pump is run for specific purposes
Make chlorine with a SWCG
Skim the Pool surface
Mix chemicals
Run a pressure side, suction side or in floor cleaner
Heat the pool or spa

You will want to make a little chlorine throughout the day. So this is a longer pump run time but you turn down the % of output from the SWCG. This gives you more flexibility as the summer heats up and you have to increase the % output of SWCG to produce more FC.

I have a slightly larger volume pool and run 80% of time at 1550psi and remaining 20% at 2350rpm. I use a robot cleaner now so need to ramp up speed for the pressure side cleaner that I retired recently.

 

[Newdude]

Pictures say 1000 words, so here's 2000 worth.






With a large pump, my SWG activates at 700 RPMs. Which speed would you rather need for 24 hour run time ? A 1.6 HP will need more RPMs for the same flow, using more energy.

A 2 speed may not have the flow on low speed to activate the SWG, depending on the rest of your system.

 

[datadr93]

Dealer 'found' a 1.6hp variable speed in stock... fully programmable and an extra $500 for what was going to charge for the 1-speed pump. His next line was 'they must have incorrect specs from the manufacturer and will have the new specs distributed to store staff today.'

I've dealt enough with sales folks in my day job and know a 'gotcha' cover when I hear one. Regardless, the end result is a more economical solution that we have more control.

 

[datadr93]

Pictures say 1000 words, so here's 2000 worth.

View attachment 582300

View attachment 582301


With a large pump, my SWG activates at 700 RPMs. Which speed would you rather need for 24 hour run time ? A 1.6 HP will need more RPMs for the same flow, using more energy.

A 2 speed may not have the flow on low speed to activate the SWG, depending on the rest of your system.

Since we're still learning all this info, could you please expand? I see the higher RPM uses more watts (thus more energy)... so not 100% what you're conveying.

Please excuse my ignorance.

 

[Newdude]

Please excuse my ignorance.

Please ask anytime.

The single speed pump only has max speed and will be an energy hog. It's a non starter.

A smaller VS pump will need to run at a higher speed to have the same flow as a larger VS pump, using more energy (but not tons). So skimming and SWG production will cost more needing to run the smaller VS pump a little higher to satisfy both.

My vote is for a 3 HP pump (or 2.7 brand depending).

 

[datadr93]

Please ask anytime.

The single speed pump only has max speed and will be an energy hog. It's a non starter.

A smaller VS pump will need to run at a higher speed to have the same flow as a larger VS pump, using more energy (but not tons). So skimming and SWG production will cost more needing to run the smaller VS pump a little higher to satisfy both.

My vote is for a 3 HP pump (or 2.7 brand depending).

Thank you for the clarification... makes more sense.

What we ended up opting is for a Jandy 1.65hp VS for our 11.4k gallon pool. Plan to run full speed during night along with heat pump (at 2250 RPM... plus run Wall-E (what we named our Dolphin). Then during the day, we'll lay solar cover and run lowest RPM (I believe it's 1400 RPM). This should give us close to 3 turnovers in 24 hour period. Reviewing the Jandy cost estimator... we would be about $35 more per year using the 1.65 vs the 2.7. Obviously we'll watch the SWG levels and adjust accordingly. This is all in theory since we don't even have concrete laid yet and running off chlorinator until the concrete around pool is completed (hopefully next week for the 3 foot area around pool).

Pool has unobstructed view of the southern sky so it gets almost 10 hours of pure sunlight during the day... we may not even need to run the heat pump most of the time. But we'll be paying close attention to evaporation and the various chemical levels. I'm sure we still have much to learn... so any advice to seasoned veterans will always be appreciated.

 

[HermanTX]

Dealer 'found' a 1.6hp variable speed in stock.

Great news. This will be better than the single speed.

This should give us close to 3 turnovers in 24 hour period.

Refer to post #11. run the pump for specific needs and not just to have a turnover amount.
The SWCG will most likely determine the longest length of time the pump will need to run but that will be at a minimum rpm to activate the flow switch which turns on the SWCG.
Please use the PoolMath app to help with that.

 

[datadr93]

Great news. This will be better than the single speed.

Refer to post #11. run the pump for specific needs and not just to have a turnover amount.
The SWCG will most likely determine the longest length of time the pump will need to run but that will be at a minimum rpm to activate the flow switch which turns on the SWCG.
Please use the PoolMath app to help with that.

Thank you. Downloaded app and will review later this evening.

My numbers I posted are 'in theory' and not in application. I haven't cracked the manual on the SWCG yet (Pentair iChlor15) to review the minimum RPM but if run at 1400 RPM... it should run at least 30 GPM... and (from what I found online)... the Pentair requires 20-25 GPM minimum to activate. Which if that's true, could I run at the lowest setting 24 hours? And use the higher setting after heavy rain, social gathering, etc?

If anyone knows any differently, please don't hesitate to correct my information.

 

[Jimrahbe]

Data,

All pools and plumbing are different.. You should experiment and find out what speed actually closes your cell's flow switch and then add about 100 RPM... Use that as the slowest speed you ever want to run.. It makes no sense to run your pump if you are not making chlorine.

Thanks,

Jim R.

 

[datadr93]

Data,

All pools and plumbing are different.. You should experiment and find out what speed actually closes your cell's flow switch and then add about 100 RPM... Use that as the slowest speed you ever want to run.. It makes no sense to run your pump if you are not making chlorine.

Thanks,

Jim R.

Thank you. Making note once all connected.

Greatly appreciated.