HELP! with correctly sizing pool pump.

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C

CP95

0
Mar 7, 2014
5
Charlotte
Need to replace a failed 1HP Northstar pump again (went through 3 in 13 seasons) and considering going to a 2 speed or VS pump this time. When looking at flow rates, pipe restrictions, etc. - having a hard time figuring out exactly what my plumbing will allow so I can determine best pump size to go with.

Here's my current setup:

Pool size is 20' x 40' and approx. 35,000

Inlet:
1 1/2" from Skimmer
1 1/2" from floor drain

* Both join at valve that outputs 2" PVC about 16" before pump inlet.

Pump:
2" PVC IN
1 1/2" PVC OUT

Sand Filter - Rated at 60 GPM:
1 1/2" IN
1 1/2" OUT to VALVE 1 (All lines remain 1 1/2" from here on out)

VALVE 1
> Universal Wall Fitting
> Valve 2

VALVE 2
> Wall Jets
> Valve 3

VALVE 3
> Stair Jets
> Swim-out Jet

Any idea what HP pump I should actually have - or if I should upgrade to 2 speed or VS (electric rates are $0.115)? Are there any choke points I can relieve, or am I limited by all the 1 1/2" pipe used by the original builder? Also any thoughts as to why I'm burning out pumps fairly regularly?

I typically run 24 hrs a day for 6 months and frequently shut down flow from either the floor drain or the skimmer depending on tasks being performed (shut down skimmer to circulate chemicals - shut down floor drains when there's an abundance of leaves or when pool cleaning with skimmer suction powered vacuum).

Any feedback would be appreciated.
 
Welcome to TFP!

Assuming you don't have a spa or any water features you haven't mentioned: With electricity around $0.11/kWh, it is unlikely a VS pump will every payback the initial investment. Your best bet is a two speed pump, run on low nearly all of the time, but with high speed still available should you need it. A 1 HP two speed should be fine. A little smaller than that would be better, but it is difficult to find two speed pumps smaller than that.

By the by, there is no point in running the pump 24 hours a day. Most pools are fine with 4 hours a day, and even if yours needs more than that, it won't be anywhere near needing 24 hours a day.

Your main limitation is the sand filter, which could be damaged by a significantly larger pump. Since there is no reason to get a larger pump, that isn't really an issue here.

The main cause for pumps burning out quickly is getting wet. If there is anything that might get the pump wet, leak, sprinklers, directly out in the rain, protecting the pump from that should improve things significantly. Constant sunlight can also be an issue, especially in desert climates, but that is less common.
 
bobodaclown said:
Your electric cost are pretty inexpensive, go with a 2-speed. Why not just replace the motor instead of the whole pump? I'd get a 1HP 2-speed motor with a high/low switch, a new seal and call it a day. 90 percent of the time run it on low. No need to run 24 hours a day.

Check out pool school: http://www.troublefreepool.com/content/165-getting-started
Specifically: http://www.troublefreepool.com/content/152-determine-pump-run-time
Click to expand...

Thanks for the links.

Is there a particular model 2 speed 1 HP motor that is a direct swap for the Northstar's OEM motor?
 
JasonLion said:
Welcome to TFP!

Assuming you don't have a spa or any water features you haven't mentioned: With electricity around $0.11/kWh, it is unlikely a VS pump will every payback the initial investment. Your best bet is a two speed pump, run on low nearly all of the time, but with high speed still available should you need it. A 1 HP two speed should be fine. A little smaller than that would be better, but it is difficult to find two speed pumps smaller than that.

By the by, there is no point in running the pump 24 hours a day. Most pools are fine with 4 hours a day, and even if yours needs more than that, it won't be anywhere near needing 24 hours a day.

Your main limitation is the sand filter, which could be damaged by a significantly larger pump. Since there is no reason to get a larger pump, that isn't really an issue here.

The main cause for pumps burning out quickly is getting wet. If there is anything that might get the pump wet, leak, sprinklers, directly out in the rain, protecting the pump from that should improve things significantly. Constant sunlight can also be an issue, especially in desert climates, but that is less common.
Click to expand...

It's stupid, but the main reason it was run 24 hrs/day is because the terminal cover of my Intermatic timer is missing so you have to be real careful when shutting off the pump to backwash, etc. I told the wife to use the breaker instead so she wouldn't risk touching a hot terminal screw. The result of shutting off the power to the Intermatic timer is that the clock reverses its spin each time - and that made scheduling impossible.

I assume I don't need a timer with the capability to select motor speed as part of the timing function if I'm only going to go to high speed when vacuuming, etc. I can just manually change the speed in those instances? Is replacing my timer with the T106 series timer the best/simplest to incorporate a 2 speed motor?
 
CP95 said:
It's stupid, but the main reason it was run 24 hrs/day is because the terminal cover of my Intermatic timer is missing so you have to be real careful when shutting off the pump to backwash, etc. I told the wife to use the breaker instead so she wouldn't risk touching a hot terminal screw. The result of shutting off the power to the Intermatic timer is that the clock reverses its spin each time - and that made scheduling impossible.

I assume I don't need a timer with the capability to select motor speed as part of the timing function if I'm only going to go to high speed when vacuuming, etc. I can just manually change the speed in those instances? Is replacing my timer with the T106 series timer the best/simplest to incorporate a 2 speed motor?
Click to expand...
Why would your Intermatic timer reverse its spin when powered off? If that is the case then I would guess that you need a new clock mechanism.
 
Most people are fine with a normal timer and a manual switch to change speeds. The only times you normally needs high speed are for things like backwashing the filter or vacuuming the pool, both of which you will be around to switch the speed switch manually. The only common exception is a suction side pool cleaner, but you haven't mentioned having one of those.

It is fairly easy to repair the timer. With two separate problems it might be best to replace the whole mechanism, which should be around $50. That will pay for it's self fairly quickly in saved electricity costs.
 
I do have a suction side pool cleaner (Polaris 340??), but I'm considering a pressure side unit so I can clean at lower speeds. The 340 requires almost the entire pump capacity to perform well.

Any recommendations on a motor model that is easily swapped with the Northstar pump?

Also - would you recommend changing any of the pad plumbing from the way it is now?
 
CP95 said:
It's stupid, but the main reason it was run 24 hrs/day is because the terminal cover of my Intermatic timer is missing so you have to be real careful when shutting off the pump to backwash, etc. I told the wife to use the breaker instead so she wouldn't risk touching a hot terminal screw. The result of shutting off the power to the Intermatic timer is that the clock reverses its spin each time - and that made scheduling impossible.

I assume I don't need a timer with the capability to select motor speed as part of the timing function if I'm only going to go to high speed when vacuuming, etc. I can just manually change the speed in those instances? Is replacing my timer with the T106 series timer the best/simplest to incorporate a 2 speed motor?
Click to expand...

Now we know why you are going through pumps prematurely!!! LOL. 24/7 run time, WOW!!!!
 
 

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bobodaclown said:
Not sure if you have the which model you have: SP4010 1 HP FR this motor SPX1610Z1BNS or the SP4007X10 1 HP MR or this motor SPX1607Z1MNS.

http://www.1stoppoolsupply.com/stan...-motor-65-diameter-frame-uprated-p-21079.html
http://www.yourpoolhq.com/pump-motor-2-speed-1-5-hp-c-face-energy-efficient-sts1152r.html
http://www.ebay.com/itm/Hayward-1-5...ement-Northstar-HAYSPX1610Z2MNS-/250991696741
http://www.amazon.com/Hayward-SPX1610Z2MNS-Speed-Replacement-Northstar/dp/B005INBKOO
http://www.poolplaza.com/merchant.mv?Screen=PROD&Product_Code=AOS-B975-4000&Category_Code=
http://store.kgpowersystems.com/a.o.-smith-b975-century-c-face-pool-and-spa-pump-motor-1-.12-hp.aspx

I'm not positive but I think you need a B975 motor.

Hope the links help. I realize some are for 1.5 HP.
Click to expand...

It's a SP4010 NS, and it looks like you're right - a B975 motor. It's on order now.

Thanks much, you guys saved me a bundle.

Now one last question - is the motor seal (or seals) that should be replaced at the same time a universal part or is it specific to the motor? Could I trouble you for a part # or link?
 
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