Variable Speed Replacement for Hayward 3/4 HP Superpump

Tjaltz

Member
Oct 7, 2018
9
SC
I have an 26,000 gal 18x36 in-ground vinyl liner pool with a Pentair FNS PLS 60 DE filter, SWG and Hayward SP2605X7 3/4 HP Pump wired for 220 volts running on a timer. My system is running 1 1/2 pipe with 115’ of suction lines and 45’ of discharge lines, plus 8 90 degree elbows and 2 45’s. The 3/4 hp pump has done a great job, but is older and uses a lot of electricity. I would like to replace it with a variable speed 220 unit , and the Hayward Super Pump VS Variable Speed Pump 230V - W3SP2603VSP has been suggested as a replacement. Since my current 3/4 hp pump does a good job, I was concerned that the W3SP2603VSP with 1 1/2 hp may be oversized with too much pressure or flow. Has anyone replaced a SP2605X7 3/4 HP with a W3SP2603VSP 1 1/2 HP? Thanks for any input, I appreciate it.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
19,756
Northern NJ
A VS pump is a variable HP pump. There is no such thing as an oversized VS pump. You just run it as slow as necessary for the HP you need.

Also a larger HP VS pump is more efficient at a slow speed then a smaller VS pump. So a 3 HP VS pump running at 1/2 HP will use less electricity then a 1 HP VS pump running at 1/2 HP.

The W3SP2603VSP should work fine for you.
 
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Tjaltz

Member
Oct 7, 2018
9
SC
Thanks. If I need to run a Variable Speed Pump at 80 percent of max speed in order to get the proper flow, is it worthwhile? Are VSP pumps that run at 100 percent any more efficient that a single speed pump? I am looking to replace a Hayward Super Pump SP2605X7 on a 26K gallon in ground. Using gauges, I determined my TDH to be 40 (7" of suction and 14 psi at the pump). I have 1.5 pipe. My existing SP2605X7 gives me about 40 GPM at 40 TDH. The VSP i'm looking at is the Hayward SP2603VSP which needs to run at 3,000 RPM (chart below) to produce about the same flow for turnover. Is reducing the speed by 400 RPM going to offer any real savings? I'm struggling to determine if it's worth it. Thanks for any input you can offer.
 

JamesW

TFP Expert
Mar 2, 2011
20,755
Is there any reason you need more than 25 gpm?

There's no "turnover" requirement.

How many skimmers do you have?
 

Tjaltz

Member
Oct 7, 2018
9
SC
I have two skimmers and one main drain. I may be wrong, I just thought it was recommended that you turnover the pool once a day for proper filtration. I am running my single speed pump about 12 hours a day during the season. At about 40 GPM that should pump 26-28K gallons in the 12 hours it runs. If it isn’t necessary to pump that much, I can run the pump less, or a VSP slower, but it looks like the Hayward Variable speed (SP2603VSP) can only handle 40TDH at full speed or 3000 rpm. Am I wrong? Will the SP2603VSP be able to suction from the skimmers/drain at 2400 or 1725? I would prefer to run the pump longer and slower to reduce electric usage. I just thought at the slower speeds the SP2603VSP couldn’t handle the 40 TDH. Thanks again. I really appreciate any help to decide.
 

JamesW

TFP Expert
Mar 2, 2011
20,755
The TDH is not a single number. It changes depending on the flow rate.

A variable speed pump at 1725 rpm should work fine.

I would leave the main drain closed or mostly closed and adjust the pump speed until you have good skimmer action in both skimmers. That's all you need as long as the SWG functions properly.

Periodically, open the main drain to flush the line.
 

Tjaltz

Member
Oct 7, 2018
9
SC
Thank you. I understand that I can significantly reduce my run time, and I will adjust it. I’m still unsure if the SP2603VSP can operate at the lower three speeds with a TDH of 40. According to the performance chart, it appears that the slowest 3 speeds won’t work with a TDH above about 32. Is that correct?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
19,756
Northern NJ
Thank you. I understand that I can significantly reduce my run time, and I will adjust it. I’m still unsure if the SP2603VSP can operate at the lower three speeds with a TDH of 40. According to the performance chart, it appears that the slowest 3 speeds won’t work with a TDH above about 32. Is that correct?
I think @JamesW is saying you are not going to have a TDH of 40 when running the pump at lower RPMS and flow rates. So it will work fine.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,733
Pleasanton, CA
Thank you. I understand that I can significantly reduce my run time, and I will adjust it. I’m still unsure if the SP2603VSP can operate at the lower three speeds with a TDH of 40. According to the performance chart, it appears that the slowest 3 speeds won’t work with a TDH above about 32. Is that correct?
TDH changes with flow rate and RPM. So at 1/2 the RPM, flow rate goes down by 1/2 and head goes down by 1/4.

For example, if the full speed operating point is 40 GPM @ 40' of head, then half speed will have an operating point of 20 GPM @ 10' of head. You don't need a head curve to determine that. You can just use the pump affinity equations.
 
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