User avatar
LTLFTcomposite
Posts: 4338
Joined: Fri Apr 23, 2010 6:06 pm
Delivery Date: 10 Dec 2011
Leaf Number: 5926
Location: Boca Raton FL

Other energy savers: Variable speed pool pumps

Sat Jun 30, 2012 3:23 pm

I've been eying the Hayward eco star pool pump as a way to save on electric. It was mentioned elsewhere here the payback on these is pretty quick. They cost a bundle, $1100+, so I'm trying to see how it pencils out...

I put an ammeter on my existing conventional 3/4 hp pump and found it's drawing 5.4 amps, so:

5.4A x 240A = 1296W x 6 hrs/day x 30 days/month = 233.28 kWh/mo @ $0.11/kWh = $25.66 / month

That would be four years payback assuming the new pump uses zero. It isn't clear from the literature how much these new pumps actually draw. There is some suggestion it is in the 200-300 watt range, which would put the payback around five years.

Does anyone have one of these and can comment on what their actual current draw is? Also, do you run them more hours/day on slow speed? I'm also wondering what makes them more efficient. Sure people say they use less electricity because they are running slower, but presumably they are pumping less water in the process, so couldn't I accomplish the same thing by reducing the number of hours my existing pump runs?

Thanks in advance for any insights.
LTL
White 2012 SV delivered 10 Dec 2011 returned 25 Nov 2014 replaced with stopgap ICE Sentra
[35 months] [35K miles] [9 Bars]
2013 Volt replaced after 36 months/30k miles with ICE Rogue

smkettner
Posts: 7006
Joined: Mon Aug 09, 2010 10:13 pm
Delivery Date: 26 Feb 2014
Location: Orange County, CA

Re: Other energy savers: Variable speed pool pumps

Sat Jun 30, 2012 8:44 pm

I agree with run the existing for less hours. Otherwise why not just get a 1/2 hp motor instead of some complex variable speed.

I don't have a pool but at the office the VSD airconditioning did not really live up to the hype.
1 bar lost at 21,451 miles, 16 months.
2 bar lost at 35,339 miles, 25 months.
LEAF traded at 45,400 miles for a RAV4-EV

User avatar
Nekota
Posts: 616
Joined: Sat Dec 11, 2010 11:16 pm
Delivery Date: 12 May 2011
Leaf Number: 2182
Location: Sunnyvale, CA

Re: Other energy savers: Variable speed pool pumps

Sat Jun 30, 2012 9:41 pm

The efficiency gains are likely overstated and I don't think your 3/4 HP motor is pulling 1200 watts either. Induction motors have a significant power factor so what you measured was VA. 3/4 of a HP is around 550 watts and even with an efficiency of 0.8 that would result in 690 Watts of real power. I keep watching for a DC motor that plugs into a string of PV panels and runs when the sun shines but no one is making one yet. Another helpful way to reduce the time the pool needs to run is to use a robotic pool sweep that doesn't depend on the main filter. The drawback is the system is no longer automatic, the sweep doesn't like to stay in the water all the time and pool covers get in the way of deploying the sweep and removing it at the end of a clean cycle. The advantage is the robotic sweep is using about 100 watts to clean the pool.

What makes the system more efficient is moving the water more slowly puts more energy into moving the water rather than heating the water. It's similar to driving a LEAF at slower speed to reduce the amount of energy lost to wind friction.
Res 20Apr2010 / Ordered 27Sep2010 / Delivered 12May2011

PV System

User avatar
TomT
Posts: 10565
Joined: Sun Aug 08, 2010 12:09 pm
Delivery Date: 01 Mar 2011
Leaf Number: 000360
Location: Foothills of Granada Hills, CA
Contact: Website

Re: Other energy savers: Variable speed pool pumps

Sat Jun 30, 2012 11:39 pm

I replaced my pool pump with the Pentair Intelliflo about three years ago when LADWP was giving a $1,000 rebate. It did in fact drop my overall energy use by the pool by more than 2/3.
59,991 miles/12 bars/289 Gids/68.54 AHr/101% SOH/101.64% Hx 7May15 w/ new Lizard (barely made the warranty).
71,770 miles/12 bars/256 Gids/59.04 AHr/88% SOH/87.92% Hx 3Mar16 at lease return.

Now driving a 2016 Volt Premier. Model 3 reserved.

User avatar
keydiver
Posts: 1051
Joined: Mon Sep 05, 2011 1:04 pm
Delivery Date: 08 Dec 2011
Leaf Number: 16484
Location: Hobe Sound, Florida
Contact: Website

Re: Other energy savers: Variable speed pool pumps

Sun Jul 01, 2012 6:06 am

I changed the motor on my pump from a 1 1/2 HP to a 2-speed, so now it runs at 1/3 HP most of the time. I also reduced the hours to 4-5 hours/day, seasonally adjusted. Those 2 things together put a big dent in my FPL bill. There are websites that specialize in pool motor swaps, which really isn't as difficult as it sounds because almost all of the motors are made by A.O.Smith, so many are interchangeable.
2012 Glacier Pearl SL - Delivered December 8, 2011
10kW Solar PV for recharging!
2006 Prius with Hymotion 5kWh PHEV upgrade
Tesla 70D | Titanium Metallic | Matte Obeche Wood Décor| All Glass Panoramic Roof
Tesla Model 3 Pre-Ordered!

User avatar
LTLFTcomposite
Posts: 4338
Joined: Fri Apr 23, 2010 6:06 pm
Delivery Date: 10 Dec 2011
Leaf Number: 5926
Location: Boca Raton FL

Re: Other energy savers: Variable speed pool pumps

Sun Jul 01, 2012 11:09 am

Nekota wrote:The efficiency gains are likely overstated and I don't think your 3/4 HP motor is pulling 1200 watts either. Induction motors have a significant power factor so what you measured was VA. 3/4 of a HP is around 550 watts and even with an efficiency of 0.8 that would result in 690 Watts of real power.

I put one of those clamp meters (digital) around one of the wires and it read 5.4 amps. Is that not an accurate way to tell how much juice it's pulling?

If it really is only 690 watts my upside is even more limited.

Nekota wrote:What makes the system more efficient is moving the water more slowly puts more energy into moving the water rather than heating the water. It's similar to driving a LEAF at slower speed to reduce the amount of energy lost to wind friction.

So you pump the water slower over a longer period of time?

Thanks to all for their feedback.
LTL
White 2012 SV delivered 10 Dec 2011 returned 25 Nov 2014 replaced with stopgap ICE Sentra
[35 months] [35K miles] [9 Bars]
2013 Volt replaced after 36 months/30k miles with ICE Rogue

User avatar
TomT
Posts: 10565
Joined: Sun Aug 08, 2010 12:09 pm
Delivery Date: 01 Mar 2011
Leaf Number: 000360
Location: Foothills of Granada Hills, CA
Contact: Website

Re: Other energy savers: Variable speed pool pumps

Sun Jul 01, 2012 11:21 am

Pool pump motors are usually 240 volt so it would be about 1,300 watts...

LTLFTcomposite wrote:I put one of those clamp meters (digital) around one of the wires and it read 5.4 amps. Is that not an accurate way to tell how much juice it's pulling?
59,991 miles/12 bars/289 Gids/68.54 AHr/101% SOH/101.64% Hx 7May15 w/ new Lizard (barely made the warranty).
71,770 miles/12 bars/256 Gids/59.04 AHr/88% SOH/87.92% Hx 3Mar16 at lease return.

Now driving a 2016 Volt Premier. Model 3 reserved.

User avatar
TomT
Posts: 10565
Joined: Sun Aug 08, 2010 12:09 pm
Delivery Date: 01 Mar 2011
Leaf Number: 000360
Location: Foothills of Granada Hills, CA
Contact: Website

Re: Other energy savers: Variable speed pool pumps

Sun Jul 01, 2012 11:23 am

Yes, due to lower pressure and volume, it takes less total energy to do so, even considering the longer running time. It is like driving the Leaf somewhere at 75 versus 30...

LTLFTcomposite wrote:So you pump the water slower over a longer period of time?
59,991 miles/12 bars/289 Gids/68.54 AHr/101% SOH/101.64% Hx 7May15 w/ new Lizard (barely made the warranty).
71,770 miles/12 bars/256 Gids/59.04 AHr/88% SOH/87.92% Hx 3Mar16 at lease return.

Now driving a 2016 Volt Premier. Model 3 reserved.

User avatar
Nekota
Posts: 616
Joined: Sat Dec 11, 2010 11:16 pm
Delivery Date: 12 May 2011
Leaf Number: 2182
Location: Sunnyvale, CA

Re: Other energy savers: Variable speed pool pumps

Sun Jul 01, 2012 11:31 am

LTLFTcomposite wrote:
Nekota wrote:The efficiency gains are likely overstated and I don't think your 3/4 HP motor is pulling 1200 watts either. Induction motors have a significant power factor so what you measured was VA. 3/4 of a HP is around 550 watts and even with an efficiency of 0.8 that would result in 690 Watts of real power.

I put one of those clamp meters (digital) around one of the wires and it read 5.4 amps. Is that not an accurate way to tell how much juice it's pulling?

If it really is only 690 watts my upside is even more limited.

Nekota wrote:What makes the system more efficient is moving the water more slowly puts more energy into moving the water rather than heating the water. It's similar to driving a LEAF at slower speed to reduce the amount of energy lost to wind friction.

So you pump the water slower over a longer period of time?

Thanks to all for their feedback.



The clamp on current meter is an accurate way to measure the current but not an accurate way to measure power since the current and voltage in an induction motor are not in phase or mismatched making the measurement not as simple as volts x amps. A killawatt meter is an accurate measurement device for power (watts), VA (volts x amps) and power factor but it works only with 120V.

The recommended practice for pool filtering is to turn over the water once per day. So if you are pumping more slowly then yes you have to run the pump longer with the effect of more of the energy goes into moving the water through the filter rather than losing the energy to friction in the pipes and filter.
Res 20Apr2010 / Ordered 27Sep2010 / Delivered 12May2011

PV System

User avatar
LTLFTcomposite
Posts: 4338
Joined: Fri Apr 23, 2010 6:06 pm
Delivery Date: 10 Dec 2011
Leaf Number: 5926
Location: Boca Raton FL

Re: Other energy savers: Variable speed pool pumps

Sun Jul 01, 2012 1:37 pm

Nekota wrote:The clamp on current meter is an accurate way to measure the current but not an accurate way to measure power since the current and voltage in an induction motor are not in phase or mismatched making the measurement not as simple as volts x amps. A killawatt meter is an accurate measurement device for power (watts), VA (volts x amps) and power factor but it works only with 120V.

The recommended practice for pool filtering is to turn over the water once per day. So if you are pumping more slowly then yes you have to run the pump longer with the effect of more of the energy goes into moving the water through the filter rather than losing the energy to friction in the pipes and filter.

I don't have a killawatt meter; I've been meaning to get one, but isn't that just for 120v stuff you can plug in? The pool pump of course is hardwired 240v.

If my low efficiency pump really is only pulling 690 watts as you suggested, it's costing me less than $14 a month vs $26 a month with the higher number. Either way if that's the upper bound to my savings it will be 5-9 years payback, seems I should be looking elsewhere for energy savings. I'll revisit it when my current pump craps out, maybe prices will have come down.
LTL
White 2012 SV delivered 10 Dec 2011 returned 25 Nov 2014 replaced with stopgap ICE Sentra
[35 months] [35K miles] [9 Bars]
2013 Volt replaced after 36 months/30k miles with ICE Rogue

Return to “Off-Topic”