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Thread: need new pump-1.5"pipe,2"pump? -update: Whisperflo installed

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    busbeepbeep's Avatar
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    need new pump-1.5"pipe,2"pump? -update: Whisperflo installed

    We have a 16,000 gal pool about 20 yrs old. The pool has 1.5" plumbing. The original pump was a Pac Fab Challenger looking pump, I don't remember the exact model. I think it was 1 HP. It worked like a champ until Katrina flooded it out. Bought a Hayward maxflo (2810x15). Lasted less than two years...the motor is not fully functional (one of the starting contact switches broke...tried to glue, broke again.., I can hot wire start it, but really dangerous, tired of dealing with it and getting shocked... anybody know where to find schematics or spare parts for these motors?) No luck fixing it, so looking at new pumps.

    With the Maxflo running, the pressure on the filter (Tagelus 60 sand filter) reads about 18-20 PSI. I run a Polaris 360 pressure side sweep, no booster required.

    Looking at new pumps. I like the Pentair Whisperflo. The single speed, full rated, energy efficient models. Should I go with 3/4HP (WFE-3) or 1HP (WFE-4). From reading the pump curves, I can see both of these can pump much better than the old 1.5HP hayward.

    Would I run into trouble using a pump with 2" suction and discharge and using reducers to adapt to my 1.5" plumbing?

    I realize the pump will not run to its full potential, but will the curve just back off or do I risk damaging a motor like this?

    Since the pipe size difference will affect the head, how then to predict what my flow may be with a new motor/pump?


    Thanks in advance.
    17,000 gallon in-ground plaster (circa 1985) | Tagelus 60 Sand Filter | Whisperflo WFE-3 3/4 hp (1.25HP/1.67SF) | 1.5" plumbing, 17psi normal | TF-100 Test Kit | Liquidator

  2. Back To Top    #2
    Can't help you, but wanted to say welcome to TFP!

    (I used to live near NOLA, but moved north after Katrina)

    8200 gallon 20' x 48" round vinyl frame pool, manually chlorinated with 10% liquid, salt added to ~2000, 12" sand filter, 1600gph pump, TF100 test kit
    Handy Links: PoolMath, TF-100 Test Kit, Pool School, Chlorine/CYA Chart
    "Shock" is a process, not a product!

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    JasonLion's Avatar
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    You might want to think about getting your current pump fixed. What you describe should be repairable.

    There is nothing wrong with reducing 2" connectors on the pump to 1 1/2" pipe. The total dynamic head will be a little higher, but that should be fine.

    Predicting the flow rate is tricky. If you have the pump curve for your current pump you can compare that to the new one and get a sense of their relative flow rates.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    i have a pump with 2 inch outs and ins and 1.5 inch existing plumbing on a 27 year old pool..works fine
    • 15K IG gunite/plaster pool • Pentair: Whisperflo EE 1 HP • Nautilus FNS + 48 DE Filter • IntelliChlor IC40 •
    • Spectrum Amerlite SAm • Admiral S20 Skimmer - Circular Weir • Kreepy Krauly •

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    busbeepbeep's Avatar
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    Ok the Whisperflo 3/4HP or the 1HP? I can't decide. With the 2" pipe, looking at the curves, I'd say the 3/4HP is sufficient. How much increase in head do I anticipate? Is the 1HP overkill?

    Any better prices than found here?
    (They offer free shipping)

    Also, in some places I've seen the whisperflo listed with a 3 year warranty, in other places a 1 year warranty. Which is it?
    17,000 gallon in-ground plaster (circa 1985) | Tagelus 60 Sand Filter | Whisperflo WFE-3 3/4 hp (1.25HP/1.67SF) | 1.5" plumbing, 17psi normal | TF-100 Test Kit | Liquidator

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    i have a 3/4 uprated to 1hp pump now ..my prior pump was a 1/2 hp uprated to 3/4 and it had the 1.5 inch outs and ins...i'm about 30 ft and 70 ft from where my piping goes to returns for reference..and i have a fair amount of 45 and 90 degree bends in my system....and i think the 1/2 hp would have been fine if it hadn't conked out simply due to age. where i got it from and at the price, the 3/4 uprated to 1hp was the only one available at the time so i took it..my only concern was potential for cavitation in the pump or would it potentially push out sand from the my filter. i've had problems with neither situation. are you returns a long ways away? what are your bends like in terms of impacting flow? i have about 5 90 degree and 4 45 degree bends in my system.
    • 15K IG gunite/plaster pool • Pentair: Whisperflo EE 1 HP • Nautilus FNS + 48 DE Filter • IntelliChlor IC40 •
    • Spectrum Amerlite SAm • Admiral S20 Skimmer - Circular Weir • Kreepy Krauly •

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    mas985's Avatar
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    Normally, I wouldn't recommend anything more than 3/4 HP Whisperflo on 1.5" plumbing but it does depend on the plumbing details:

    Distance from pool to pad?
    Number of suction lines pool to pad?
    Number of return lines pool to pad?

    Given this information, I can better predict what the flow rates and head loss might be with each pump.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    busbeepbeep's Avatar
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    Pool to pad, about 30ft

    (1) 1.5" suction
    (1) 1.5" return
    17,000 gallon in-ground plaster (circa 1985) | Tagelus 60 Sand Filter | Whisperflo WFE-3 3/4 hp (1.25HP/1.67SF) | 1.5" plumbing, 17psi normal | TF-100 Test Kit | Liquidator

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    mas985's Avatar
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    Looking back at your original post, I am a bit concerned at the operating pressure given the pump you have. 18 PSI is a bit higher than average for that pump and a single suction line. Are you sure you do not have a separate line for the skimmer(s) and main drain? I would have expected closer to 14 PSI than 18.

    If not, then you may have higher head loss than average on the return side. This could be due to more fittings than average or smaller eyeballs. It may be worth investigating a bit to see if you have any issues with the return side plumbing.

    Assuming the pressure is correct, a 3/4 HP Whisperflo is likely to increase the filter pressure and flow through the filter more than your current pump. For the given information, my estimates are as follows:

    Current Pump is ~ 38 GPM @ 59 ft of head (19 PSI)
    Whisperflo 3/4 HP is ~ 42 GPM @ 74 ft of head (23 PSI)

    You could use the Whisperflo although your pressure will be high and the head loss fairly high. The operating point is more than 10% off of the best efficiency point so you will be losing quite a bit of efficiency. I would definitly not go with the 1 HP pump as this would be too powerful for your plumbing.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    busbeepbeep's Avatar
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    Thanks for all your input mas985.

    There is only one suction line at the pad, so the main drain and skimmer must tie in somewhere close to the pool.

    I'm not sure how to diagnose any problems with the return plumbing.

    I already ordered the Whisperflo, so I hope I'll be ok. If you are saying it will not be efficient, then what pump would you have recommended? Another pump like the old one?
    17,000 gallon in-ground plaster (circa 1985) | Tagelus 60 Sand Filter | Whisperflo WFE-3 3/4 hp (1.25HP/1.67SF) | 1.5" plumbing, 17psi normal | TF-100 Test Kit | Liquidator

  11. Back To Top    #11
    the 1/2 hp whisperflo is very close to the equivalent of the calculations mas did for your current pump.
    • 15K IG gunite/plaster pool • Pentair: Whisperflo EE 1 HP • Nautilus FNS + 48 DE Filter • IntelliChlor IC40 •
    • Spectrum Amerlite SAm • Admiral S20 Skimmer - Circular Weir • Kreepy Krauly •

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    mas985's Avatar
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    Every pump has an optimum operating point called the best efficiency point. Unfortunately, it is difficult to design a plumbing system to hit this point exactly. Because your plumbing system has fairly high head loss even for a low HP pump, the efficiency will not be as good as it could be. However, this does not mean it will be bad either. My only point was that you will be losing about 10% efficiency because of the high head loss. For most pools, if you can get within 5% of the best efficiency point, that is pretty good.

    With 1.5" plumbing, the lower the HP pump the better. The 3/4 HP Whisperflo is really a 1.2 BHP pump so the effective HP is still pretty high. Medium head pumps such as the Maxflo or the Superpump tend to have less flow for the head loss so are better suited for 1.5" plumbing. However, since the Whisperflo is about 10% higher efficiency than either the Maxflo or SuperPump, you may end up at the same overall efficiency anyway.

    If you can change the order, I would also consider 2 speed pumps since they really make head loss moot at low speed and are more than 30% more efficient than the high speed setting.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    busbeepbeep's Avatar
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    ok...pump on the way, but won't get here until next monday.

    old pump is currently on, but the motor was damaged greatly getting it started last time...meaning once it's off, it's not coming on again. the capacitor starting switch is broken

    this may be a stupid question, but I'm curious
    the pressure is going up, not much flow...the filter needs to backwash. The tagelus filter has a top mount multiport threaded valve. Can I hot-switch the valve while the motor is running? I can imagine it is not good for the pump, but this pump will be on the curb in a week anyway. Will I damage the valve or filter or perhaps even myself?
    17,000 gallon in-ground plaster (circa 1985) | Tagelus 60 Sand Filter | Whisperflo WFE-3 3/4 hp (1.25HP/1.67SF) | 1.5" plumbing, 17psi normal | TF-100 Test Kit | Liquidator

  14. Back To Top    #14
    Mod Squad JohnT's Avatar
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    Quote Originally Posted by busbeepbeep
    Can I hot-switch the valve while the motor is running? I can imagine it is not good for the pump, but this pump will be on the curb in a week anyway. Will I damage the valve or filter or perhaps even myself?
    The multiport gasket can be damaged pretty quickly doing that.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    busbeepbeep's Avatar
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    Installed

    got the pump in today and installed it. so far so good.

    Filter PSI reading 19-20 PSI right after the much needed backwash. So I'm guessing around 65ft of head?

    The Polaris 360 is scooting along much better than it did with the old pump. This pump is much quieter than the old Maxflo.
    17,000 gallon in-ground plaster (circa 1985) | Tagelus 60 Sand Filter | Whisperflo WFE-3 3/4 hp (1.25HP/1.67SF) | 1.5" plumbing, 17psi normal | TF-100 Test Kit | Liquidator

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    mas985's Avatar
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    A bit lower pressure than what I had expected so thats good. I place head loss between 65-70ft with that pressure but you would need to get a suction measurement to be exact.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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