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Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
So on a personal note I'm getting inground pool and yes will have licensed electrical do the work. Curious about something.

I'm getting a 2.7HP variable speed pump single phase. I will also need a GFI on the equipment pad. Can they both share a circuit?
 
The pool control panel will likely have breaker spaces you can use to power other branch circuits. Would you really want a general use circuit powered off of one leg of the 2 pole GFCI breaker for the pump?
 
This may be another item where the horse power is "Sears" horsepower and not real HP. The nameplate amps for the Jandy pump mystic Pools linked is 16A at 120V. That seems like a real 1.25 to 1.5HP to me. But this is still too big to put a convenience receptacle on the same circuit as 210.23(B)(2) limits fastened-in-place equipment to 50% of the circuit rating when you mix general receptacles with fixed equipment.

How big is this pool? Pump seems rather large, but being variable speed maybe this doesn't matter as much. Water in a pipe does have a speed limit though, so hopefully you have a piping system that can deal with 80 to 90 GPM if necessary. When I had a pool, it had a 3/4 HP pump which I upgraded from the 1/2 that was on it. 1HP and 70 GPM would probably be all that my piping could take.
 
Little Bill said:
Most every pool pump I wired for were dual voltage 115V/230V. I think all but one customer wanted 115V, the rest I wired for 230V.
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Older pools from the 60's and 70's ran on a single pole 15 or 20 amp with a UF as the power source. Simple pools. One pump only.
Now......
 
suemarkp said:
This may be another item where the horse power is "Sears" horsepower and not real HP. The nameplate amps for the Jandy pump mystic Pools linked is 16A at 120V. That seems like a real 1.25 to 1.5HP to me. But this is still too big to put a convenience receptacle on the same circuit as 210.23(B)(2) limits fastened-in-place equipment to 50% of the circuit rating when you mix general receptacles with fixed equipment.

How big is this pool? Pump seems rather large, but being variable speed maybe this doesn't matter as much. Water in a pipe does have a speed limit though, so hopefully you have a piping system that can deal with 80 to 90 GPM if necessary. When I had a pool, it had a 3/4 HP pump which I upgraded from the 1/2 that was on it. 1HP and 70 GPM would probably be all that my piping could take.
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The ratings on the VS pumps are THP (Total Horsepower). As per the OP, 2.7 pump to be used is closer to a single speed 3 HP.

I too am interested why a 2.7 HP is spec'd. This is a size I will use for spa jets or a water feature. This size I generally running 3" or 4" piping running full bore at 3450 RPM. Close to 140+ GPM.
I have to perform calculations for the given vessel and flow needed to choose the correct pump and the proper size pipe to allow for the flow needed but not exceed the velocity. Pump curves are the go-to when choosing. Knowing flow rates and velocity on given size piping is part of the equation. There are charts out there with that information.

Just on the surface, the 2.7 HP is WAY oversized. That size is intended to move a ton of water.

Historically, prior to the VS pumps, my new builds were fine with a single speed 1 hp pump for a "basic" pool at a 12-hour run. Anything bigger would destroy filters and create excessive flow through heaters. A bypass would have to be installed.

The VS pumps I install run 24/7 at a lower RPM and still meet the flow rate. Running 24/7 the pool is constantly getting filtered and chemically treated. More efficient running constantly than a 12-hour clip on a single speed.

Any water features I do will run on their own pump and do not share the main filtration system. In my opinion its duty is to treat and heat only.
 
If this is basic pool with no added water features, do these calcs.

Calculate the pool volume. LxW x Avg Depth x 7.5
Calculate the GPM needed to turn the pool over every 8 hours.

Example: 20k gallon pool
42 GPM
2520 GPH
In 8 hours, it will turnover 20,160 gallons

Look at the pump curve and where the GPM falls. 40-50 feet of head is a good number range to work with.

The Hayward pump will have that required GPM at a certain RPM.

You can get all this will a smaller VS pump. The 2.7 is kind of like getting a Ferrari that you never get out 2nd gear.

The idea is to run these pumps 24/7 at a low RPM. It should ramp up when it's called for heat. Most heaters need 2600-2800 RPM's to fire.
You will see a low amp draw at low RPM's and get continuous filtration and treating running 24/7.

The days of 12 hours ON 12 hours OFF are gone.
 
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