Replacement Pump

[PKDallas]

My current pump screams at me every time it turns on. It's gotten so bad my neighbor actually came over to check and make sure everything was okay. The pump label has worn off completely, but in the right light I think I was able to decipher the markings. It is a Hayward Northstar Pump, I believe model SP4000ZL1, and the motor I believe is the SP1610-Z-1-MNS, if that sounds correct.

My pool has six returns in the main pool, 6 or 7 jets in the raised hot tub, a spillover waterfall, two skimmers, and the main drain with two drains connected at the bottom of the pool.

I don't believe I need a two speed or variable speed motor, as my electricity is so cheap it isn't worth the extra cost (8.3/kwh). I tried to buy the same pump I already had, but was told the Northstar was old and had troubles and I wouldn't be able to find one. I was pointed towards the Hayward Tristar (SP3215EE). I believe this one has a 1.5 HP and 1.6 SF for THP of 2.4. I believe my old pump was a 1.5 HP, 1.25 SF for a THP of 1.875. Would this be an acceptable replacement pump? Any issues I should be aware of with the Tristar?

I would like to attempt to replace the pump myself, which will take some plumbing. I'm confident I can cut/glue the PVC as I've done this before, but I have zero experience with electrical work. I'm assuming this will need to be hard wired to the timer, which appears to be how the old pump is hooked up. Is it as simple as connecting the ground, then hooking up the two wires?

Thanks for any help.

 

[BoDarville]

Hi PKDallas,

I'll address two parts of your post.

I don't believe I need a two speed or variable speed motor, as my electricity is so cheap it isn't worth the extra cost (8.3/kwh)

Although 8.3 cents / kWh is a good rate, I would at least look into the cost difference between a single-speed pump and a 2-speed of equivalent HP. Many people assume if the pump speed is reduced by 50% that it will reduce the power consumption by 50%. In actuality, reducing the pump speed by 50% will reduce the power consumption by 87.5% (http://www.grundfos.com/service-support/encyclopedia-search/laws-of-affinity.html). True, at 1/2 speed you will have to run the pump about twice as long to get an equivalent water turnover compared to running it at full speed. Factoring in the increased run-time, you are looking at a net energy savings of around 65-75% for an equivalent water turnover vs. a single-speed pump. Since a pump should last around 8-10 years, a 2-speed pump will be a hedge against rising energy costs in the future. Variable-speed pumps can offer even more energy savings, but I would agree that those are probably not worth the extra cost and complexity given your current electric rates.

I would like to attempt to replace the pump myself, which will take some plumbing. I'm confident I can cut/glue the PVC as I've done this before, but I have zero experience with electrical work.

If you have zero experience with electrical, it is best to hire a professional or at least work with a friend or relative who has electrical experience. In addition to wiring the pump to the electrical source, you will want to make sure that the safety to the heater is properly wired so that if pump stops while the heater is on that it will shut off the heater. I know someone who installed a new pump on their own and was unaware of the need for the heater safety connection. One day they were running the pump & heater to heat their spa. After shutting off the pump, the heater kept running and it exploded later that night due to the superheated water trapped inside the heater.

 

[JasonLion]

A two speed pump is almost invariably a good investment, even though real world savings are usually closer to 50%. Your pool is also fairly small, so you could do well with a pump slightly smaller than the one you have now.

The electrical work to hook up a pump isn't really difficult, but there are some major safety issues to be aware of. If you don't have any experience with electrical work, it is best left to a professional. Or, if you are really dedicated to doing it your self it would be best to do some extensive reading in advance so you know which things need to be watched out for to keep you safe.

 

[bobodaclown]

You don't have to replace the whole pump, you can just replace the motor. Save yourself some money and time.
The pump consist of 2 sections the wet section, pump/impeller and the motor.
Here's a link to the manual: http://www.hayward-pool.com/pdf/manuals/NorthStar.pdf

This motor may meet you needs: https://www.americanbestpoolsupply.com/ ... 129181.htm

If you decide to get a motor only make sure you replace the seal.

 

[mas985]

Many people assume if the pump speed is reduced by 50% that it will reduce the power consumption by 50%. In actuality, reducing the pump speed by 50% will reduce the power consumption by 87.5% (http://www.grundfos.com/service-support/encyclopedia-search/laws-of-affinity.html).

That's true only if the motor efficiency doesn't change. Unfortunately, in a two speed motor, efficiency drops by about 50% when running at low speed so power consumed by a two speed pump on low speed is about 75% of the high speed power (1/4 vs 1/8). Affinity laws do not take into account changes in efficiency.

 

[BoDarville]

PKDallas:

Out of curiosity, I did a couple of internet price searches on similarly rated single-speed and 2-speed pumps. I agree that your current 1.5 HP pump is a bit much given the size of your pool. Therefore, the two pumps I looked at are the Pentair WF-4 (single-speed) and the Pentair WFDS-4 (2-speed). Both pumps can be wired to 230V and both are rated at 1 HP with a Service Factor HP (SFHP) of 1.65, so as to keep this comparison as close to "apples to apples" as possible. What I'm finding is that the cost differential between the lower priced single-speed and the 2-speed is around $80-$100, depending on who you buy from. Even at your current electric rates and using a 50% power savings estimate instead of the more optimistic affinity numbers, you should recoup the extra cost of the 2-speed pump within a year given an equivalent water turnover of around 1.

I would hate to see you spend good money on a brand-new single-speed pump and then be stuck with the ongoing higher operating costs for the next 8-10 years when you could have spent just a bit more up-front on a 2-speed and enjoy the ongoing energy cost savings that will pay back the cost differential many times over the life of the unit.