New Pump / Pool Cleaner - Variable Speed or 2 Speed

[socalowner]

Hello Everyone,

I just purchased a home with a large pool. Existing equipment is in my signature. I have read through many posts but appears that best thing to do is create my own and get some personalized feedback.

1. Replace my existing Pentair Whisperflo 1.5HP pump with a Pentair VS or 2speed pump. Currently, I'm running 8 hours pump time but that's based upon previous pool guy and Leslie's recommendation. I would assume pump time needs to increase with higher summer use. I'm sticking with Pentair brand. In addition, the jacuzzi has a Pentair Whisperflo pump too so I'll have a backup Jaccuzi pump when I replace my pool pump. I've been told that I will need the Pentair Intellicomm adapter to interface with my AquaLink RS and can obtain 4 speeds with that upgrade for the VS.

2. I'm firing the pool guy and he's taking the Hayward XL pool cleaner that is his. I would like to purchase an electric robot to run my new pump at it's lowest output but still allow the chlorine generator to work. Heater will only be used for spa, so I'm not worried about.

Questions:

1. What is the lowest setting I can run my "new" pump to allow the chlorinator to generate and maintain maximum energy efficiency?
2. Is the Pentair VS 3HP more power than I'll need? If so, what HP 2 speed pump would you recommend 1,1.5?
3. Will the low speed on a 2 speed pump allow the chlorinator to generate?
4. Will I really ever need 4-8 speeds to operate my pool more efficiently than my current setup or will a 2 speed create the same type of energy savings.
5. Will I need an control system upgrade adapter if I choose a 2 speed pump?
6. If I add solar in the future, how much more power will I need to pump the water up to the solar and how long will I have to run at higher speeds to accomplish that?
7. I'm looking for a robot to clean my pool that includes stairs that run the width of one side (30+ feet). My pool is basically a 42'x22' rectangle with another 14'x14'x14' triangle on one end. Seems like the Dolphin Supreme M4 has the best ratings. How many days a week should I run the robot and for how long? Do they make robots that just stay in the pool versus removing every time?

Any insight or recommendations would be amazing. Thank you

 

[Bama Rambler]

Welcome to TFP.

1. That's going to be a trial and error type thing. Just run it fast enough to keep it from tripping out on low flow.

2. Maybe, I'd first ask a few questions.
a. What is your electric rate?
b. What size and length is your plumbing?

3. Most likely it would, but there's a bit of uncertainty because we don't know the plumbing layout.

4. Most likely two speeds will be all you really need unless you have water features that would benefit from more specific flows.

5. No. That system should run a 2-speed pump if you have a spare relay.

6. There's where a VS pump would be a good idea. You can fine tune the flow through the panels with a VS pump.

7. I have no experience with pool cleaning robots. (now if you're looking of fighting robots, we can talk)

 

[jblizzle]

Welcome to TFP!!!

The easiest way to save money on power is to not run your pump. 8 hours is likely more than enough any time of year.

To you questions:

1. Hard to say, it would likely work with just about any 2-speed on low, and with a VS you could likely go a little lower in rpm

2. Certainly more power than you need. Is this pump only for filtration? If so, even the 1.5HP is overkill. I would suggest a 1HP 2-speed motor & impeller replacement only ... no need to replace the pump. Although with a VS you can dial the speed down more, but it will cost $900 instead of ~$300-400 for just a motor and impeller.

3. Any Whsipserflo 2-speed should have high enough flow rate to run the SWG on low.

4. If the pump is only for filtration, then you really only need 2 speeds, a low speed for filtering and a higher speed for vacuuming/backwashing. The VS will operate at a lower speed and thus use less power, but costs a lot more up front.

5. I don't know. Typically you just need 2 relays in a controller to control the 2 speeds.

6. Solar heating is most efficient at higher flow rates. With a 2-speed you will need to run on high (the 1HP would be plenty). With a VS you could trade a lower speed to save money, but will get less heating. If you want to add heat, you have to run the pump when the sun is out ... the longer you run, the more heat you get.

7. Personal preference. I run my robot every few weeks, but I guess I accept some dirt in the pool (the pebble hides it). I don't think any are good at stairs. You just have to brush off the stairs yourself. They all claim to need to be removed from the pool, but I think some people leave them in all the time.

 

[socalowner]

I'll have to check on the size and length of plumbing. At first glance, looks like 2" with 40'-50' from pump to skimmer/main drain. The pool was built in late 70's and I have copper lines. I've been told that the lines will eventually need to be replaced/repaired due to salt system corrosion.

Only had the home 12 days but averaging 2.5-2.75 kWh's a day just for pump. Currently, averaging $0.18 a kWh but I will not know tiers and cost until end of billing cycle.

Never realized I could replace the motor but now that makes sense giving all the housings look very similar. Anyone know the energy consumption for the low speed on Pentair 2 speed motor compared to my current single speed 1.5HP Pentair?

 

[jblizzle]

A 2-speed motor on low moves 1/2 the amount of water for 1/4 the amount of power. So if you got a 1.5HP 2-speed motor, and ran it twice as long as now to move the same amount of water (which is likely overkill), you would lower the power consumption by 50%. Go to a 1HP 2-speed and you will save even more. And certainly you can shorten the run time.

Your power is on the verge of where we say a VS makes sense ... but I think that is only if you need to completely replace the pump. Needing only a motor will certainly be the cheapest option up front.

BUT ... if you get a rebate on the VS pump, then that makes it a little easier to swallow the extra upfront cost.

 

[linen]

Welcome to tfp, socalowner

Post a model number for you pump and we can suggest a 2-speed motor. If you can't find the model number, post a picture of whatever labels are on the pump and motor.

 

[jblizzle]

I just wanted to add one more question. Is your current pump wired for 115V or 230V? Single speeds often can be either, but most 2-speed motors are only 230V (except for a couple of the 3/4HP that seem difficult to find).

 

[socalowner]

Awesome, thanks guys, I'll have to check on the 115V or 230V:

WhisperFlo
Model #WFE-6

 

[jblizzle]

Here is a really good price (I think) for a direct 1.5HP 2-speed replacement. You could also just put a smaller impeller on it as well.
http://www.sunplay.com/Pentair-Motor-07 ... 71320s.htm

Although I did not look around too much.

If you replace the motor, you will also need a new shaft seal (or get a full go-kit for all the seals).

 

[linen]

I think that pump appears to be 230V only and it is a 1.5 hp full rated motor. In addition to the link jbliz posted, another good 2-speed replacement would the a.o. smith B2983, they also make the B2983T with a timer attached if you need it for a little more. I am not certain about this, but the B2983 may be a little more efficient on low than the one jbliz posted.

Is your current pump on a timer, and if yes, which one?

If you replace just the motor, you will also need a seal kit such as: http://www.amazon.com/Pentair-Go-Kit-32-9-WhisperFlo/dp/B001F5S1YQ/ref=pd_bxgy_lg_text_y

 

[socalowner]

I looked and have a 2.0inch copper intake line and 2.0inch copper return line read the maximum flow for suction/return with that line size is 75GPM regardless of what flow my pump can generate. So my current 1.5HP may be creating too much friction and slowing down the flow of water?

The clean filter pressure is 16, so 16x2.31=36.96. I need to meaure vacuum pressure at the pump and add to filter pressure to arive at resistance to flow.

Once i know the "feet of head" I can look at the Pentair Whisperflo Performance Curve to determine the most efficient pump.

http://www.pentairpool.com/images/produ ... ve_new.gif

I haven't measured yet, but if my vacuum pressure is 10-15 then I'm looking "feet of head" of 45-50 which actually shows a energy efficient single speed pump is necessary for most efficient GPM.

At 45 feet of head a 1/2 HP generates 60GPM at 4.4amps
At 50 feet of head a 3/4 HP generates 70GPM at 5.6amps

My current 1.5HP pump at 50 feet of head is generating 110GPM at 8.8amps but max flow is 75 anyways. So essentially, I could swith to a 1/2HP or 3/4HP single speed pump with the same assumed run time and reduce the energy consumption by 40-50%?

 

[duraleigh]

read the maximum flow for suction/return with that line size is 75GPM

That is am "optimum" guideline that is commonly misunderstood. Given enough HP, you can push much more than that through the pipe.

 

[linen]

My current 1.5HP pump at 50 feet of head is generating 110GPM at 8.8amps but max flow is 75 anyways. So essentially, I could swith to a 1/2HP or 3/4HP single speed pump with the same assumed run time and reduce the energy consumption by 40-50%?

You will move less water with a lower hp pump, so that will mitigate some of the savings. Additionally, as you suspect, your current pump is likely not pushing 110 gpm through your system, so that saves a little power with your current pump since lower flow rate means lower power (kind of counter intuitive). With that said, a lower hp pump would save a little more electricity when compared to your current pump, but you will be achieving that if you go with your current pump and a 2-speed motor.

 

[socalowner]

I believe the old owner/pool guy installed the pump based upon their calculation of 52,000 gallon pool with 1 turnover a day. Running my single speed 1.5HP Whisperflo pump for 8 hours with 40-50 "feet of head", my pump can generate 110 GPM (although my line size will restrict that some).

My current pump is using 9.60amps per hour which translates to 2.2kWh, 17.6 kWh's per day, 528 kWh's per 30 day month, 6424 kWh's per year. I confirmed by shutting off all power except for pump and looking at hourly energy usage on SDGE website. My pool energy consumption is basically all at Tier 4 with SDGE at $0.36. Therefore, I'm looking at an anual cost of $2312 if rates stay the same, which they won't becasuse they increase in the summer.

Pentair Performance curve shows at 50 feet of head:

Single Speed 1.5HP Whisperflo @ 110 GPM - 17.6 kWh's a day (9.60 amps per hour @ 8 hours, for 1 turnover)
Single Speed 3/4HP Whisperflo @ 70 GPM - 17.25 kWh's a day (6.0 amps per hour @ 12.5 hours, for 1 turnover)
Two Speed 1HP Whisperflo @ 50 GPM (low speed) - 11.96 kWh's (3.0 amps per hour @ 17.33 hours, for 1 turnover)
Two Speed 1.5HP Whisperflo @ 55 GPM (low speed) - 12.67 kWh's (3.5 amps per hour @ 15.75 hours, for 1 turnover)

Two Questions:

1. I'm I reading the Pentair perforamance curve correctly for max GPM on low speed?
2. If not, what GPM could a 1HP or 1.5HP Whisperflow generate on low speed?

 

[jblizzle]

The GPM does not matter. And the 1 turnover requirement is not a good rule of thumb. Read this: pool-school/pump_run_time

Part of the problem is that the head loss is a function of the pump speed. So while you may have 50 feet of head on high speed, when you switch to low the head loss is much less. And calculating the head loss of your system is not trivial ... and really serves no purpose.

All that really mattes is know that low speed moves ~1/2 the amount of water as high speed for ~1/4 the electricity. So, if you run on low for twice as long as you used to on high (or single speed), then you will have moved the same amount of water, but saved 50% of the electrical cost.

 

[linen]

I agree with jbliz, don't worry about gpm. More than likely you do not need 1 turnover a day to remain clear. Are you certain on your volume? 52000 is very large.

 

[socalowner]

Yes, if anything 52,000 is being conservative. 11 feet deep at one end.

Thank you, i previously read the provided link and was only using 1 turnover to keep assumptions constant because my pool is maintaining at current 8 hour run time. I still need to modify run time to find minimum amount necessary.

That being said, my rough calculation and expert feedback shows the 1HP two speed pump should provide most savings and be sufficient for my pool needs.

 

[socalowner]

I installed a new 1HP Pentair Whisperflo two speed motor and its working well. On low speed, chlorintor is generating and The PoolCleaner is functioning.

However, the filter pressure gauge is reading 2, well starts at 2 so could be 0. Water sprays out of the filter pressure relief valve when pump is on.

Is it normal to have psi that low? The gauge does work.

 

[BoDarville]

Thank you, i previously read the provided link and was only using 1 turnover to keep assumptions constant because my pool is maintaining at current 8 hour run time. I still need to modify run time to find minimum amount necessary.

The 1 turnover per day was an old guideline. However, that has turned out to be a very poor indicator of actual required pump run time. I would recommend reading this article to help you fine-tune your pump run time: Determine Pump Run Time.

I used the process described in that article to see if I could reduce my pump run time from my typical 3-4 hours/day during swim season. This past summer, I ran my pump about 40-60 minutes a day on average and had crystal clear water. Keeping the pool properly chlorinated is an important step in keeping the water clear and I'm diligent about doing that.