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Thread: Could a new pump cause higher pressure?

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    hanesian's Avatar
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    Could a new pump cause higher pressure?

    Would it be unusual to see an increase in normal pressure as a result of changing pumps?

    I just replaced an old single speed pump with a new dual speed pump, and while the pump seems to be working well the 'normal' pressure for the new pump is about 20 psi compared to about 15 psi for the old pump, even after multiple backwashes & rinses. It keeps the same 20 psi whether running in normal filter mode or recirculate mode, which leads me to think it must simply be the new pump and not an issue with the filter possibly being clogged, but just wanted to ask the troops here.

    Any feedback welcomed.
    25,000 gallon, vinyl IG, Pentair Superflo 1 HP Dual Speed pump, Hayward S-240 sand filter, SWG, Raypak M206A heater, Polaris Pool Cleaner 280

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    Re: Could a new pump cause higher pressure?

    If your new pump is more powerful than the old one then an increase in pressure is normal. It should be fine unless you are over 50 PSI as that is the maximum working pressure of the filter. I wouldn't worry about it.

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    Re: Could a new pump cause higher pressure?

    Sounds like a bad gauge. Does the gauge go to zero when the pump is off?

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    Mod Squad jblizzle's Avatar
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    Re: Could a new pump cause higher pressure?

    On recirculate, the gauge should have 0 pressure.
    Sounds like time for a new gauge ... the glycerin ones from tftestkits.net are really nice and cost about the same as the junk you will find locally.
    Jason, TFP Moderator
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    Re: Could a new pump cause higher pressure?

    If the gauge is in the multiport, it can still register pressure while in recirculate. In any case, it does sound like a bad gauge.

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    Mod Squad jblizzle's Avatar
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    Re: Could a new pump cause higher pressure?

    oh, maybe that is true with the top mount sand filters. Thanks James
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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    hanesian's Avatar
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    Re: Could a new pump cause higher pressure?

    The pressure gauge was just purchased new yesterday, so if it's bad it's defective. It does go to zero when the pump is turned off.

    I do have a top mount sand filter, and the gauge is in the multiport, FWIW.

    The pumps are both 1 HP.
    25,000 gallon, vinyl IG, Pentair Superflo 1 HP Dual Speed pump, Hayward S-240 sand filter, SWG, Raypak M206A heater, Polaris Pool Cleaner 280

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    n240sxguy's Avatar
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    Could a new pump cause higher pressure?

    Is the pump the same hp and service factor as the old one? If the hp is the same, but the service factor is higher, it could actually be more powerful than the old pump, and a pressure increase would make sense.
    Was this gauge used with both pumps?


    30K gallon IG vinyl. 1.5HP 2-speed Waterway Mustang pump. 600 lb sand filter. Polaris 280. Circupool SI-60+. TF-100

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    mas985's Avatar
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    Re: Could a new pump cause higher pressure?

    When you switch between normal and recirculate modes on the filter, do you shut off the pump first?

    What was the old pump make/model and the new one (not sure which is in your sig)?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Could a new pump cause higher pressure?

    n240sxguy,

    Both pumps 1 HP, the old had a SF of 1.4, the new a SF 1.25. I should add the old pump was over a decade old and was coaxed through last summer only with plastic welding and bondo.

    The same gauge was NOT used on both pumps. Last year's gauge was dead by this spring so I replaced it.

    mas985,

    Yes, I always switch off the pump before changing from one mode to another.

    I updated my signature already. The old pump was a very old A.O. Smith Century Centurian B128; the new is a Pentair Superflo Dual Speed.


    Let me add some further data in case it may be relevant.

    Starting last summer I began seeing air bubbles coming from the returns upon starting the pump, so I figured I had a suction side leak somewhere to diagnose this spring.

    The old pump was DOA this spring and would not start, which set back my opening by a week and had me worried about a big algae issue, as I typically have leaf reside/sludge on the bottom from holes in the mesh cover. After installing the new pump and starting it I was not surprised to see I still had some air bubbles coming from the returns, but not only on start up, but fairly continuously. Still, given the late opening and the fact the pump seemed to be working great beyond the air bubbles and the mentioned higher pressure reading, I have been running it while watching it closely and backwashing frequently as soon as pressure rises to about 22 psi.

    Obviously I have to diagnose and address the suction leak issue, but I was focusing first on getting the pool open and hopefully passing the 3 SLAM tests. The water is improving over the past 2 days but is still very cloudy so I continue to SLAM and backwash. It's progressed from swamp like to light green and cloudy and seemingly improving each day.

    I have never swaped out pumps before though, so wasn't sure if this increase in typically pressure was an indication of further concern - perhaps my sand filter needing a deep cleaning - or if it was a non issue. That's why I only asked about the pressure issue, since I am trying to prioritize my troubleshooting between pumps, leaks and filters! Given the answers so far, I figured the additional information might be relevant, so I offer it now.

    I'm also surprised to see that when I run the pump on the slow speed the pressure drops way down to about 5 psi, and although it manages to maintain prime the water level in the basket drops visibly to about half full. Does this sound normal? I've never had a dual speed pump before.

    So to recap, my concerns/questions are:

    1. Should I be concerned that the new pump operates at about 20 psi vs the old pump of 15 psi?

    2. Is it typical for the low speed on a dual speed pump to have a pressure of about 25% of the fast speed? (5 psi vs 20 psi?)

    3. Could the new pressure gauge be the source of this pressure change?

    4. Could my suction side leaks be contributing to this pressure issue, or would that be limited to air bubbles in the return?

    5. Could the pressure issue be caused by an algae bloom or problem in my sand filter that should be deep cleaned to improve the pressure?


    Sorry for the long treatise, and any feedback or suggestions welcomed.
    25,000 gallon, vinyl IG, Pentair Superflo 1 HP Dual Speed pump, Hayward S-240 sand filter, SWG, Raypak M206A heater, Polaris Pool Cleaner 280

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    n240sxguy's Avatar
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    Re: Could a new pump cause higher pressure?

    1. I don't think so.
    2. Yes.
    3. Very possible.
    4. Should be limited to air bubbles.
    5. Deep cleaning sounds like a good idea.


    30K gallon IG vinyl. 1.5HP 2-speed Waterway Mustang pump. 600 lb sand filter. Polaris 280. Circupool SI-60+. TF-100

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    Re: Could a new pump cause higher pressure?

    The old pump was a very old A.O. Smith Century Centurian B128
    That is motor, not a pump. What was the pump model? If you don't know, can you post a picture of it?

    1. I can't really tell if the pressure increase is reasonable unless I know what the old pump was. But still 20 PSI is quite high for a 1 HP SuperFlo so it could indicate that something went wrong during the change out.

    2. Yes, that is called the pump affinity effect.

    3. Possibly. The new gauge could be reading the correct pressure while the old gauge was not.

    4. If anything, that would lower pressure.

    5. Yes, definitely. Higher pressure is caused by filtering out algae. You might want to get rid of that first before worrying too much about the pressure. But if you backwash the filter, does it ever go below 20 PSI? If not, then it is probably not the algae.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Could a new pump cause higher pressure?

    Quote Originally Posted by hanesian View Post
    The pressure gauge was just purchased new yesterday, so if it's bad it's defective. It does go to zero when the pump is turned off.

    I do have a top mount sand filter, and the gauge is in the multiport, FWIW.

    The pumps are both 1 HP.
    Correction: I have a SIDE mount sand filter (not a top mount), but the gauge is definitely in the multiport.
    25,000 gallon, vinyl IG, Pentair Superflo 1 HP Dual Speed pump, Hayward S-240 sand filter, SWG, Raypak M206A heater, Polaris Pool Cleaner 280

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    Re: Could a new pump cause higher pressure?

    Quote Originally Posted by mas985 View Post
    That is motor, not a pump. What was the pump model? If you don't know, can you post a picture of it?

    1. I can't really tell if the pressure increase is reasonable unless I know what the old pump was. But still 20 PSI is quite high for a 1 HP SuperFlo so it could indicate that something went wrong during the change out.

    2. Yes, that is called the pump affinity effect.

    3. Possibly. The new gauge could be reading the correct pressure while the old gauge was not.

    4. If anything, that would lower pressure.

    5. Yes, definitely. Higher pressure is caused by filtering out algae. You might want to get rid of that first before worrying too much about the pressure. But if you backwash the filter, does it ever go below 20 PSI? If not, then it is probably not the algae.
    Apologies on the old pump info. Its so old I cannot see any identifying information beyond Hayward. The model number is lost to the ages. Here's a photo of the removed and now out of service pump.



    After I back wash the filter the pressure never falls below 20 psi, both on filter and recirculate, so presumably not indicative of an algae/filter problem. Interestingly, the pressure drops down to just below 15 (the old pump's normal pressure) when back washing or rinsing. I'm not sure if that is significant or not.

    Thanks again for all your help.

    - - - Updated - - -

    Quote Originally Posted by n240sxguy View Post
    1. I don't think so.
    2. Yes.
    3. Very possible.
    4. Should be limited to air bubbles.
    5. Deep cleaning sounds like a good idea.


    Sent from my iPhone using Tapatalk
    I think I'll definitely replace the gauge just to remove that variable from the equation. And I'll do a deep clean of the sand filter once I get past the OCLT tests.
    25,000 gallon, vinyl IG, Pentair Superflo 1 HP Dual Speed pump, Hayward S-240 sand filter, SWG, Raypak M206A heater, Polaris Pool Cleaner 280

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    Re: Could a new pump cause higher pressure?

    That is a Hayward Superpump. There is a metal tag right below the pump pipe outlet. Does it have a model # on it (e.g. SP2607X10)?

    Usually Superpumps have motors with a service factor close to one although it looks like the motor was replaced at one time. But if the original pump was the SP2607X10, then the new pump should have about the same pressure because the head curves are similar. However, the old pump impeller may have been damaged so it was pumping less.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Could a new pump cause higher pressure?

    Mark,

    Unfortunately the details on the metal tag are not legible.



    I can't tell you the exact history of the pump as I only bought the house a couple years ago, but the pool itself is about 25 years old, so the pump and/or motor could be pretty old.

    Glad to have the new pump in, just have to get the system humming along properly!
    25,000 gallon, vinyl IG, Pentair Superflo 1 HP Dual Speed pump, Hayward S-240 sand filter, SWG, Raypak M206A heater, Polaris Pool Cleaner 280

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    Re: Could a new pump cause higher pressure?

    That's unfortunate.

    But anyway 20 PSI is a little high for your new pump and would indicate quite a bit of head loss somewhere on the pressure side of the pump.

    Was any of the other plumbing changed when the pump was swapped out?

    Interestingly, the pressure drops down to just below 15 (the old pump's normal pressure) when back washing or rinsing. I'm not sure if that is significant or not.
    It could be but do you remember if it was the same with the old pump in backwash mode?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Could a new pump cause higher pressure?

    Do you have solar heating panels and if so are the engaged / on?
    16x32 IG Vinyl, 13,000 Gals. Hayward S-244T sand filter, SP2810X15 pump
    (1.5 HP motor) Raypak PR266AEN (266k btu) gas heater. TF-100 Test Kit.
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    hanesian's Avatar
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    Re: Could a new pump cause higher pressure?

    Quote Originally Posted by borjis View Post
    Do you have solar heating panels and if so are the engaged / on?
    No solar heating in my system at all.
    25,000 gallon, vinyl IG, Pentair Superflo 1 HP Dual Speed pump, Hayward S-240 sand filter, SWG, Raypak M206A heater, Polaris Pool Cleaner 280

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    hanesian's Avatar
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    Re: Could a new pump cause higher pressure?

    Just an update for any following along.

    Just to be certain, I replaced the new pressure gauge with a newER gauge. No luck. It's still showing 20 psi.

    At this point I'm going to focus on passing the OCLT tests, then I'll try deep cleaning the filter. Will report back later with outcome.
    25,000 gallon, vinyl IG, Pentair Superflo 1 HP Dual Speed pump, Hayward S-240 sand filter, SWG, Raypak M206A heater, Polaris Pool Cleaner 280

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