Pump upgrade (Houston): 2-spd versus VS recommendations

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P

PandT

0
Sep 22, 2013
11
Pearland,TX
Noob needs help. Pool built 1999. Bought house 2009. Main pump is dying a noisy death and must be replaced. Love what we've found on TFP and plan to go BBB to save $ and effort. Also interested in going SWCG. Pool is in full sun, equipment gets afternoon sun (pump temp ratings are 50C and 40C which give little thermal margin). Automation would be nice, but we get plenty of lightning plus random neighborhood power outages. We are interested in recommendations about 2-speed versus VS pumps for our setup - what would drive going to one or the other? We love technology - just not for the sake of the latest "ooh shiny" - it's gotta do its job and last.
Thanks, Patrick & Teresa
 
Welcome to TFP.

Since you're in Houston, your power is going to be pretty cheap. Given that, a 2-speed would be a better choice than a variable speed. Also, since you say the existing pump is noisy, you may be better off just replacing just the motor with a 2-speed model. I assume that you need to 2 hp because of the spa requirements. Otherwise that pump is way too big for that size pool.
 
Also you don't have to replace the whole pump, you can just replace the electric motor section. If you go with a smaller sized 2 speed motor you may have to change out the impeller. It still may be cheaper than changing out the whole pump.
 
Thanks much for the feedback. The main pump has been nickel-and-dime repaired by First American home warranty for the last 4 years. We thought it needed to be replaced to begin with. They have since fixed leaks multiple times, replaced the impeller last year, and now it sounds like a low rider dragging its back end (and leaking again). We'd rather just replace it now and know we don't have some other issue that's gonna bite us on it.

2-speed is where we were leaning. Now I just wonder about sizing it. From what I've seen on TFP it looked like 3/4, maybe even 1/2, would be enough. Would that work? Would we have to replumb the spa into the pump running the waterfall?

Thanks again,
Patrick
 
Appreciate the help. Here are the particulars:

Main pump: AO Smith B855. 3450 rpm, 2.0 HP, 230v 1 phase, SF 1.10, 50C ambient

2nd pump: AO Smith p/n 35-5339 (model illegible). 3450rpm, 230/115v @ 7.1/14.2A, 40C ambient

Spa blower: Polaris model 1-470-02. 1.5 peak HP, 240v 1 phase 3.8A

DE filter: Pentair FNS Plus 60. 60 sq ft, 150 GPM, max wk press 120psi, 6.0lbs DE

Manifold: Pentair valve assy model SM2-PP2, valve model SM-20-2, max pressure drop 6.0psi @ 95GPM, rated flow 125GPM

Spa: 6' DIA, 20" deep at seats, 3' deep at feet (4' DIA), 6 jets ~0.5", 1 jet ~1"

2" PVC plumbing (at least the part above ground). Inlet heads are in my signature. 4 Compool 180-90-180 valves, 1 Jandy Everlube body valve (to cleaner jet).

Do you need any other specs?

Thanks,
Patrick

(Edit) P.S. main pump will not prime as of yesterday
 
Are the spa jets actually 1/2" or is that just the exit port (i.e. eyeball) that you are measuring? Most jets are 3/8" or 7/16" diameter and are located deep inside of the spa exit port (i.e. you can't see them from the outside).

If the main pump runs the spa jets, then you probably don't want to downsize.
 
mas985 said:
Are the spa jets actually 1/2" or is that just the exit port (i.e. eyeball) that you are measuring? Most jets are 3/8" or 7/16" diameter and are located deep inside of the spa exit port (i.e. you can't see them from the outside).

If the main pump runs the spa jets, then you probably don't want to downsize.
Click to expand...

Yes, those rough dimensions were at the eyeball. With a 2-speed, how would we size it for using high speed to run the spa (which is not often)?

Thanks for your help!
 
Mark,

Thanks much for the sizing info. One more question before we pull the trigger: I found another post where you mention motor life is less than half 80,000 hours. Running more hours at less power will help - but how does the MTBF vary as a function of time and low vs high speed?

Thanks,
Patrick
 

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I have no data on that but there are only a couple of components that usually go bad and they have little correlation to the number of hours of run time. Also, the motor MTBF quoted is a mean but the failure rate has a very large standard deviation and it is because of maintenance issues:

1 - The bearings will usually fail because the seal failed and water leaked into the bearings rusting them. This is why it is very important to check for pump leaks and fix them as soon as they are detected. If the seals are kept in good condition and never leak, then the bearings should last a very long time. We see a lot of this one on the forum because the leaks are not caught fast enough.

2 - Capacitors can fail and I can only surmise that it is because of either poor quality or voltage spikes. Otherwise, the capacitors should not really "wear out". Heat can affect them as well so #1 can cause an issue with the capacitor as well.

3 - Centrifugal switch (only some motors) can fail because it is a mechanical device and the contacts get dirty and sometimes the springs break. So this one has some dependency on run time but probably more related to on/off cycles.

The winding's generally will not usually fail unless the motor is overloaded (#1) but the thermal limiters should shut down the motor before that happens. Other than that, the motor should really last for ever.
 
Thanks for the insight.

Apart from seeing water on the pump housing / pad, how are leaks detected that could get to the bearings? In our case, the Pool Guy refused to fix the latest pump leak till we got a pool leak fixed - and as soon as we did, it started screaming like a banshee ... Probably the bearings. And then he told home warranty company the pump was bad because we let it run dry ( our water bill for refills says otherwise).

Thanks,
Patrick
 
The only way to tell if a pump is leaking is to look for water around the base. Once a week it is a good idea to inspect the pump while running and make sure everything is dry.
 
Mark,

I checked out the motor you linked above, and wonder about just replacing it versus the whole pump for two reasons:
(1) pump housing has had leaks, some worse than others, the whole 4 years we've lived in this house. Replacing it may be necessary you think?
(2) will the 2 HP impeller overload or accelerate wear out of a motor uprated to 2 HP?

(Edit) two possibles I see are both $655 at INYO:
Hayward Super 2 EE - SP3015X202AZ, 1.5 HP, SF 1.35, 230v @ 9.7A
Pentair Whisperflow - WFDS-28, 2.0 HP, SF 1.10, 230v @ 10.0/3.5A

Thanks,
Patrick
 
If the housing is leaking, then yes a new pump might be your best bet.

A 2 HP up rated pump is identical to a 1.5 HP full rated pump in the same pump line so there is no difference at all.

I would probably lean more to the Whisperflo than the Super II.

What was the brand/model# for your old pump just to make sure?
 
That is a Sta-Rite pump and looks to be either the Dura-Glas or Max-E-Glas but the basket doesn't match.

Anyway, the WFDS-6 or WFDS-28 should work fine.
 
mas985 said:
That is a Sta-Rite pump and looks to be either the Dura-Glas or Max-E-Glas but the basket doesn't match.

Anyway, the WFDS-6 or WFDS-28 should work fine.
Click to expand...

Mark,

Great, thanks. One last pump choice question: **If** we got good lightning protection, it sounds like ROI is the reason to go VS or 2-speed. Our unregulated power runs about 0.14/kWHr. Running WFDS-6 / -28 ($655) on Low (3.5A) will get 3 full turns of pool volume in 14 hrs. Intelliflo VS ($929) on speed 2 (1.9A) has comparable GPM, and would take ~35 months for ROI (ignoring any contribution from other than lower speed use). Is that the right Intelliflo model to consider? What are your thoughts?

Thanks,
Patrick
 
Mark,

Well, we decided to go with the Whisperflo 2-speed. Then we tried to buy one. Could not find any Pentair dealers (from their website list) in the Houston area that stock ANY 2-speed pumps. The carry them only as special order (2 weeks). Internet ordering could get it that quick, but the delivery fast enough (pump already dead) was so $$ that wife agreed money was better spent on full retail cost of Intelliflo VS.

So, one set of Intelliflo dynamic head calculations later and I have one remaining puzzle. Pentair manual says NEVER EVER EVER exceed 0.635 meters of vacuum. How can I derive my system vacuum? (Recall pump is dead)

Thanks,
Patrick

P.S. Main pump head calculated out at 14' @ 20 GPM, ramping to 42' @ 160 GPM. Based on keeping head loss in known range (with valve system rated 6.0 psi drop @ 95 GPM), am setting Max Speed to 2500 RPM. Based on turning pool volume 3x in 24 hours, making a min rate of 28 GPM for 14000 gal pool, the min rate is slightly below 750 RPM so am setting to 600 RPM; however, I will begin with a low end of 1200 RPM and work my way down to find the true minimum RPM for normal operation.
 

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