Clippings by jscozz

 Sort by: Last Updated Post Date Post Title Forum Name 

Variable Speed Pump Schedule

posted by: SteveScan on 10.29.2011 at 09:20 am in Pools & Spas Forum

Hi all. Just wanted to share with you guys how we run our filter pump. We had an in-ground pool built this year (24,000 gallons, raised spa, Pentair Intelliflow pump, 2 skimmers, Polaris sweep, saltwater chlorinator). I wanted to minimize our electrical cost, so I installed a flowmeter and made some observations about how pump speed affects flowrate and electrical usage. What I learned is that minimum electrical usage occurs at minimum speed. At high speed (3450 RPM), one turnover takes 3.8 hours at a cost of $1.07. At minimum speed (1100 RPM), one turnover takes 15.9 hours and costs $0.22 (assuming $0.1 per KWH)

So, I run the pump as slow as possible. The saltwater chlorinator needs 30 GPM minimum which occurs at 1250 RPM so this is our low speed. We run the sweep (with booster pump) two hours a day. It runs at the correct speed (28-32 RPM) with the filter pump at 3000 RPM, so this is our high speed. I could probably remove the flow restrictor in the sweep line and slow the pump, but would make for less surface cleaning action at the skimmers. We enjoy the sound of the spa fountain in the evening, which is nice at 1500 RPM, so this is our medium speed.

During the swim season, we filter the water two turnovers per day. Off-season, we filter the water one turnover per day. To get this, we run at low speed 16 hours during the swim season and 3 hours in the off-season.

Here is the schedule:
Swim Season: Two turnovers total
7 - 8 am Low speed (to start up)
8 - 10 am High speed (to sweep and skim)
10 am - 5 pm Low speed (to filter)
5 - 8 pm Medium speed (to enjoy)
8 pm - 4 am Low speed (to filter)
4-7 am Off

Off-Season. One turnover total.
7 - 8 am Low speed (to start up)
8 - 10 am High speed (to sweep and skim)
10 am - 12 pm Low speed (to filter)
5 - 8 pm Medium speed (to enjoy)
8 pm - 7 am Off

At 1250 RPM, flow is 30 GPM and power is 236 Watts
At 1500 RPM, flow is 39.9 GPM and power is 281 Watts
At 3,000 RPM, flow is 91.5 GPM and power is 1870 Watts
Notice that going from low to high speed, flow increases by 300% and power by 800%. That is why minimum electrical cost occurs at minimum speed.
Flow is per a Cole-Parmer S-05611-14 flowmeter
Power is per the Pentair pump

NOTES:

<none>
clipped on: 04.22.2012 at 04:48 pm    last updated on: 04.22.2012 at 04:49 pm