Change to VS Pump or not?

[richmgreen]

My pool has about 26,700 gallons. I have a flow meter inline that indicates the system is running at 48 gal/min. To turn the water just once requires me to run 9.3 hours. I usually run it about 14 hours a day. I also have a 1.5HP hayward Super Pump and all 1.5" pipping. Looking at upgrading to a VS Pump to save on energy. Just not seeing how I will save on electricity running at lower speed on the vs pump for twice as long to turn the water over even once? I have a salt generator and heat pump as well. Both require approx 20 gpm flow.,

Can someone help explain how a VS pump will save me money under those conditions?

I'd certainly like to save money if I can.

Thanks
Rich

 

[JamesW]

There is no reason that you need to get any specific number of "Turnovers".

You can run at 20 gpm for very low cost.

 

[JamesW]

Your current power usage is probably about 1,500 watts.

At 14 hours, that's 21 KWH per day or about $4.41 per day at $0.21 per kWH or about $132.30 per month.

With a VS pump, your power usage should be about 200 watts.

If you run at 200 watts for 24 hours, that's 4.8 kWH or 23% of your previous energy usage.

4.8 kWH per day is about $1.00 per day (@ 0.21 per kWH) or about $30.00 per month.

That's a savings of $102.30 per month (@ 0.21 per kwh).

 

[JamesW]

In this example, 40 GPM costs about 550 watts.

However, that's assuming a poorly designed system.

The amount of power a pump requires for each flow rate depends on the system design.

Well designed systems use much less power for the same flow in GPM compared to a poorly designed systems.

Going to about 20 to 30 GPM will cost about 200 to 300 watts.

 

[richmgreen]

In this example, 40 GPM costs about 550 watts.

Going to about 20 to 30 GPM will cost about 200 to 300 watts.

View attachment 468519

So, just run at the lowest gpm that keeps the skimmer working and produces enough chlorine through the Slat Gen? Forget the idea of clean water through turnover? I have a 1.5hp pump. Should I go with VS pump producing 1.65hp? I know the Pentair Super is a direct replacement for the Hayward Super pump I have now.

Thanks
Rich

 

[JamesW]

So, just run at the lowest gpm that keeps the skimmer working and produces enough chlorine through the Slat Gen? Forget the idea of clean water through turnover?

Yes.

I have a 1.5hp pump. Should I go with VS pump producing 1.65hp?

That will work.

You can also get an Intelliflo VSF and you can limit the speed as needed.

A bigger VS pump is quieter at the same flow rate because it runs slower.

If noise is a concern, then bigger might be better.

 

[pjt]

The huge benefit of a VSP is their efficiency at low RPMs. Run your pump at the minimum speed that still meets your requirements (SWG flow, skimming, etc.). I operate my pump at 1,000 rpm 24/7, which uses around 75 watts. That equates to $6/month in electricity. I like the constant chlorination, skimming, circulation, and filtering. You might need a slightly higher rpm when operating your heat pump.

 

[richmgreen]

Hi pjt. Isn't the HP of the IntelliFlo 011028 very large for the size pool? I have a 1.5HP Hayward now. All my plumbing is 1.5". I think all of the IntelliFlo pumps are large HP and 2" piping. Can you set whatever RPM you want on the pump, or are there a certain number of preprogrammed RPM settings?

Thanks
Rich

 

[Newdude]

You can dial it down as low as you need. A larger pump moves the same water with less energy / rpms saving you in the long run.

The only downside is it takes a long time to get a ROI so premature pump failure may ruin the maths in your favor.

 

[setsailsoon]

Hi pjt. Isn't the HP of the IntelliFlo 011028 very large for the size pool? I have a 1.5HP Hayward now. All my plumbing is 1.5". I think all of the IntelliFlo pumps are large HP and 2" piping. Can you set whatever RPM you want on the pump, or are there a certain number of preprogrammed RPM settings?

Thanks
Rich

You can always turn down the speed control but you have a pretty large pool. There may be times when it's nice to have the higher flow rate if needed. Rest of the time you can run very low speeds and get all those savings that James explained in his usual complete math and science response. Or you could go the super cheap route of just replacing the motor with a variable speed version. I did this on the previous pool but always had an inferiority complex about that decision. All the experts on here have a BIG Pentair metal housing massive pump... I was stuck running my whimpy 1.5 hp plastic Jandy pump. How is the pool controlled?

I hope this helps.

Chris

 

[JamesW]

Can you set whatever RPM you want on the pump, or are there a certain number of preprogrammed RPM settings?

You can set a top maximum speed and you can set any speeds you want.

For days without the heat pump, you can probably do about 15 to 20 gpm.

On days where you use the heat pump, just do about 25 to 30 gpm.

The IntelliFlo VSF gives you a flow reading, which is nice for dialing it in.

It also shows you the power, so you know how much power it is actually using at each speed and flow.

 

[richmgreen]

I appreciate all the information. My decision is between the Pentair SuperFlow VSP, which is a direct replacement for my Hayward Super Pump or go with the Pentair IntelliFlo3 VSF 3.0HP. There are many articles that warn about going with a pump too large for your system can cause issues. The intelliflo3 has all 2" connections. So I'd have to use 2" to 1.5" reducers. Just don't know if going that large will cause issues. The intelliflo3 provides a lot more control and claims 90% energy savings vs 80% for other models.

So, want to definitely change to VSP, just not sure which.

Any experience out there with the IntelliFlo3 VSF 3.0HP ?

Thanks
Rich

 

[JoyfulNoise]

The HP rating is mostly meaningless with a VSP. Think of it as a variable HORSE POWER pump. When running at lower RPM’s your HP is lower. So in reality, the max HP doesn’t matter because you’re never running it that high. I have a 10 year old Pentair IntelliFlo and there’s a max speed limit setting that I put at 3000RPM. So when the pump turns on and goes into PRIMING mode, it never goes faster than 3000rpm. I don’t think I have ever run my pump at the max speed of 3450rpm. And like others it runs all day at 1500rpm which is about 230W or so.

 

[BMerrill]

Pipe flow rate efficiency is best achieved if the velocity is kept below 6 feet a second.
For a 1-1/2" PVC SCH 40 pipe this equates to a flow rate of 35 gallons a minute = 2100 gallons an hour.
Once this flow rate is exceeded, the efficiency, because of friction in the pipe in a pressure system, starts to greatly dimension.

As an example from actual measurements of my system.
For 2" pipe the 6 ft/s velocity = 55 GPM, pump @ 1600 rpms, uses 275 watts/hour.
Increase to 75 GPM, 2000 rpms, 500 watts.
Increase to 100 GPM, 3000 rpms, 1595 watts.

 

[pjt]

Any experience out there with the IntelliFlo3 VSF 3.0HP ?

That's an excellent pump. Do you have automation?

 

[ajw22]

There are many articles that warn about going with a pump too large for your system can cause issues.

None of them here.

Go back and ask those people who wrote the articles about what the issues are. Or ask them to come here and defend their opinions.

Either pump will serve you fine. You will not see the difference between 90% energy savings or 80% energy savings.

I prefer Pentair but you need to match your VS pump with the automation you have or may get in the future. And I would only get the IntelliFlo3 with its optional control panel.

 

[JamesW]

There are many articles that warn about going with a pump too large for your system can cause issues.

That's true for a single speed pump.

For a variable speed pump that can be a problem if someone does not know what they are doing.

You can set the top speed and that means that the pump is never "Too big".

 

[setsailsoon]

Rich,

You've landed on two great choices. My new pool design is similar size to yours. If I can afford it I'll go with Pentair and it will be 3 hp minimum no matter what for this pool. Here's why:

• There are times I need a lot of flow. Wife will want this when we are on the patio and she wants to see the infinity flow over towards the lake.
• My previous pool was 12,800 gal. The Century Green 1.65 met my needs but almost no spare capacity at times. With this pool 2x the previous I wouldn't consider a small pump. @JamesW did some of his calculation magic to show I need a LOT of flow for my long infinity edge.
• We will install solar heating and need the velocity to maximize heat transfer when the bypass valve closes. There are several other things you may do in the future that could require high flow.
• They are really well made. Most of the cheaper pumps are synthetic material that can warp or crack easier.
• Many (most) of our experts prefer that Pentair.

I hope this is helpful and good luck with your project. Please do keep us informed.

Chris