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Thread: Help with Pump Sizing - Suction & Return Limitations

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    Help with Pump Sizing - Suction & Return Limitations

    Hi All-

    I'm in the early stages of a pool remodel and need a little help with pump sizing. I'm contracting out new plaster and tile, but want to replace/replumb the equipment pad myself. Most of the resurfacing companies quickly bid the equipment portion of the remodel and I don't feel they'll take the time to analyze what the best option will be given the current layout and pipe size. Anyway, I'm looking to simplify the original setup and maximize efficiency however possible.

    The pool & spa was built in the late 1970s and is around 16K (18K MAX). The spa does not have jets, only a blower feeding a few holes in the bench. Our plan is to abandon the blower and heater as we do not want to heat the pool or spa. We'll use the spa as a lounge area and for the spillover/waterfall feature. I want to cut all of the pipes at the equipment pad and start fresh. I'm looking for a simple setup - main pump & booster, 48 or 60 DE Filter, (2) 3 way valves and whatever check valves are needed for the spa.

    Back to pump sizing... I'm stuck with 1.5" PVC for the suction and returns & 3/4" for the pressure cleaner (currently a newer 280).

    (1) 1.5" suction line from the skimmer (main drain connects to skimmer)
    (1) 1.5" suction line from spa drain
    (1) 1.5" return line to pool (3 eyeballs)
    (1) 1.5" return line to spa (1 eyeball)

    Currently we run the pool with 100% pool suction and 50/50 on the pool & spa returns. Should I try to calculate what my total feet of head will be with the new layout and use a smaller single speed sized to the maximum flow rate of the 1.5" plumbing or will I benefit with a variable speed pump? We have no problem with the added expense if it will cost less to operate over the lifespan of the unit. Thanks for any and all help.

    A few pics...

    Current mess:



    25K Pebble, 2 Speed, DE Filter

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    mas985's Avatar
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    Re: Help with Pump Sizing - Suction & Return Limitations

    Unless you need the flow rate for something, which is sounds like you don't, just go with the smallest pump possible and I would recommend a two speed.

    WFDS-3/24 is a good choice but may be a little too big for your plumbing. A SuperFlo SF-N2-3/4A, SF-N2-1A
    or the Hayward SuperPump SP2607X102S are good choices for pools with single suction/return 1.5" lines.

    What is the distance from the pool to the equipement?

    What was you old pump model and filter pressure?

    What do you pay in electricity cost ($/kwh)?
    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: Help with Pump Sizing - Suction & Return Limitations

    Quote Originally Posted by mas985
    Unless you need the flow rate for something, which is sounds like you don't, just go with the smallest pump possible and I would recommend a two speed.

    WFDS-3/24 is a good choice but may be a little too big for your plumbing. A SuperFlo SF-N2-3/4A, SF-N2-1A
    or the Hayward SuperPump SP2607X102S are good choices for pools with single suction/return 1.5" lines.

    What is the distance from the pool to the equipement?

    What was you old pump model and filter pressure?

    What do you pay in electricity cost ($/kwh)?
    Not sure exactly what the old pump is. The pump portion is labeled Hydropump Model 700H 6B. The motor is a Magnetek Century 1.5HP.

    The pressure is 10-11 psi with a clean filter and 100% pool suction & 50/50 pool & spa return.

    The skimmer is 16' to the equipment. I would guess the main drain adds another 15'- 16' to the skimmer. The closest pool return is 17', the farthest is 30'. The spa return is 38'.

    Electricity costs for Fresno, CA are tiered from $0.12 to $0.34. We just moved here last month, so I don't have a ton of data to analyze. I can definitely see the usage spike when both the main pump & booster are running on PG&E's hourly smart meter history. My guess is we'll spend a lot of time in the $0.34/Kwh tier.

    The booster pump is a 3/4hp PB4. Is there a more energy efficient option? I have a 20amp single phase 220V feed to the pump & booster.

    Thanks!
    25K Pebble, 2 Speed, DE Filter

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    mas985's Avatar
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    Re: Help with Pump Sizing - Suction & Return Limitations

    Given that California electrical rates will probably only go up over time, a VS pump is probably a good investment. Plus it offers the flexibility of setting the optimum flow rate for your setup. But with your plumbing, you probably don't want to run the pump faster than about 2400 RPM at most.

    But either way a two speed or variable speed, you will save a lot of money on energy costs.

    As for the booster pump, there aren't really any more efficient options other than getting rid of it and finding a cleaner that doesn't require a booster. Many don't and one cleaner that seems to run on the lowest flow rates is the ThePoolCleaner. A variable pump should be able to run that without too much difficulty with a little tweaking of flow rates and valve settings. Another option is a robotic which has it's own pump and is much more efficient way to run a cleaner than using your pool pump. But as always, it comes down to cost and how much you are willing to spend.
    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: Help with Pump Sizing - Suction & Return Limitations

    Quote Originally Posted by mas985
    Given that California electrical rates will probably only go up over time, a VS pump is probably a good investment. Plus it offers the flexibility of setting the optimum flow rate for your setup. But with your plumbing, you probably don't want to run the pump faster than about 2400 RPM at most.

    But either way a two speed or variable speed, you will save a lot of money on energy costs.

    As for the booster pump, there aren't really any more efficient options other than getting rid of it and finding a cleaner that doesn't require a booster. Many don't and one cleaner that seems to run on the lowest flow rates is the ThePoolCleaner. A variable pump should be able to run that without too much difficulty with a little tweaking of flow rates and valve settings. Another option is a robotic which has it's own pump and is much more efficient way to run a cleaner than using your pool pump. But as always, it comes down to cost and how much you are willing to spend.

    Thanks for the reply. Given what you know about the pool. Is one of the two speeds you listed above a better choice? What are the major differences between the Whisperflo & Superflo pumps?
    25K Pebble, 2 Speed, DE Filter

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    mas985's Avatar
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    Re: Help with Pump Sizing - Suction & Return Limitations

    For most pools, two speed pumps tend to be more economic over the life of the pump simply because they are cheaper. The VS pumps save more in energy but cost more up front. However, VS pumps tend to make more sense the higher the electrical costs become so in California, it is usually the pump of choice. In my case, it was much cheaper for me to modify my single speed pump that it was to get a brand new VS pump with a controller. So controlling the pump is also a consideration. If you already have a controller, then the decision is a little easiler although some of the VS pumps now have built in timers so that is less of an issue.

    The two speed pumps that I had recommended are at the lower end of the HP range for all three models. The efficiency of the pumps as measured by gallons pumped/watt-hr are about the same for all the pumps but the Whisperflo has a higher flow rate and shorter turnover time while the Superflo/Superpumps have lower flow rates and longer turnover times which can have some benefits.

    The Whisperflo on your pool might have a full speed flow rate of 61 GPM or a 4.4 hour turnover while the Superflo would have a 47 GPM flow rate and a 5.7 hour turnover but the cost per turnover would be about the same. On low speed, the turnover is twice as long but the energy uses is 1/4 as much so overall you will save about 50% on energy costs when operating on low speed. With the variable speed, you can basically set the turnover rate to what ever you are looking for up to about 12 hours per turn.

    It is not an easy decision but really any of the pumps would save you money. The VS pumps just cost you more up front but will save you more down the road.
    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: Help with Pump Sizing - Suction & Return Limitations

    Quote Originally Posted by mas985
    For most pools, two speed pumps tend to be more economic over the life of the pump simply because they are cheaper. The VS pumps save more in energy but cost more up front. However, VS pumps tend to make more sense the higher the electrical costs become so in California, it is usually the pump of choice. In my case, it was much cheaper for me to modify my single speed pump that it was to get a brand new VS pump with a controller. So controlling the pump is also a consideration. If you already have a controller, then the decision is a little easiler although some of the VS pumps now have built in timers so that is less of an issue.

    The two speed pumps that I had recommended are at the lower end of the HP range for all three models. The efficiency of the pumps as measured by gallons pumped/watt-hr are about the same for all the pumps but the Whisperflo has a higher flow rate and shorter turnover time while the Superflo/Superpumps have lower flow rates and longer turnover times which can have some benefits.

    The Whisperflo on your pool might have a full speed flow rate of 61 GPM or a 4.4 hour turnover while the Superflo would have a 47 GPM flow rate and a 5.7 hour turnover but the cost per turnover would be about the same. On low speed, the turnover is twice as long but the energy uses is 1/4 as much so overall you will save about 50% on energy costs when operating on low speed. With the variable speed, you can basically set the turnover rate to what ever you are looking for up to about 12 hours per turn.

    It is not an easy decision but really any of the pumps would save you money. The VS pumps just cost you more up front but will save you more down the road.

    Thanks again! My wife and I went to pick out tile yesterday and decided to upgrade to Wet Edge Satin Matrix from Altima in the process. Since we increased our refinish budget, I think I'm going to stick with a two speed and a new digital dual timer to sync with the booster.

    I'd like to stick with a 230V pump since the wiring is already in place. It appears the only 230V pumps on your list are the Hayward & the SuperFlo SF-N2-1A. Any chance you could check the flow rates of the pumps based on your previous calculations? The SuperFlo is already set for 1.5" plumbing, but I'd have to reduce the Hayward. Does it make sense to plumb the entire pad in 1.5" vs a mix of 1.5 & 2? Also, I'm thinking of moving up to a 60 Sq Ft DE filter from 48. Do you see any issues with the larger filter size?
    25K Pebble, 2 Speed, DE Filter

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    mas985's Avatar
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    Re: Help with Pump Sizing - Suction & Return Limitations

    The 1 HP SuperFlo would be about 56 GPM and the 1 HP SuperPump about 51 GPM. The SuperPump would be about 5% more efficient than the SuperFlo since it is a slightly smaller pump.

    As for the plumbing, since you are replacing the pump anyway, I would go with all 2" on the pad and replace all of the copper that is in the pad with PVC. If the pump is 1.5", you can use a reducer right at the pump.

    As for the filter, bigger is always better but 48 sq-ft is plenty big anyway, especially for the new pump. Even at full speed, the flow rate should be less than 60% of maximum. So unless there is a problem with the filter or you are cleaning too often, you could stay with that.
    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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