Variable Speed Pumps Save Energy and Money
You may not know that that a standard pool pump uses more electricity than any other appliance in the home, except for an air-conditioner. You also may not know that most pumps are too big and use more energy than you need to keep the water sparkling clean.The culprit: a single-speed pump. A small pump is probably fine if all you want to do is circulate the water, but it might not have enough speed to run your pool cleaner, waterfall or other electrical extras that need a blast of energy.If that's the case, your pool service probably installed a pump large enough to handle the extras. But with only one speed, it's running full-blast even when your pool cleaner and waterfall aren't operating.That huge waste of energy is costing you about 80 percent more in electric bills.Don't let the high cost of running your pool outpace its value as your family's go-to place for fun, relaxation and keeping cool. Making your pool more energy-efficient will save hundreds of dollars a year.
Frank Bowman, owner of Frank Bowman Designs in Raleigh, North Carolina, says his customers who have switched report saving $300 or more a year on their electric bills.A variable-speed pump costs more than twice a single-speed model, but you'll recoup the cost in lower electric bills within two years, he estimates. Plus, he says, the pumps are quieter and last longer than older pumps.As an alternative, two-speed pumps cost less than variable-speed models. And although they're not as efficient as variable-speed pumps, they use far less energy than the single-speed unit.
Here are a few tips:
• Replace your single-speed pump with a variable-speed unit. High-performance models from such manufacturers as Pentair Water Pool and Spa let you run them on low most of the time. You can crank them up bit by bit when you need to run accessories.The manufacturers claim the pumps can cut energy use by up to 90 percent compared with single-speed pumps.
• Run your pool pump less often. Most manufacturers recommend running it between eight and 10 hours a day in the summer and about half that in the winter.
• Put a timer on the pump so it automatically shuts off, and set it to run only when you're paying off-peak rates.
• Switch to LED lighting, which uses up to 75 percent less energy than traditional incandescent underwater lights, and lasts for years.
• Keep your chemicals in balance. If you don't, your filter can run non-stop and the water will never sparkle.
• Clean trap baskets, filters, and pool walls and floor regularly. Clogging can prevent the water from flowing freely. The harder the pump has to work, the more you'll pay to run it.
Submitted By: Frank Bowman Designs serves all of North Carolina, Raleigh, Chapel Hill, Cary, Lake Gaston and the Triangle . We are a complete outdoor contractor installing outdoor kitchens & fireplaces, natural stone & paver patios, landscaping, swimming pools & spas, pool houses, cabanas and much more...Our speciality is unique and unusual swimming pools & spas. Visit Frank Bowman Designs atwww.FrankBowman.com or Contact us at Frank@FrankBowman.com or (919) 291-8354.
Comments
Though I agree that the 1 HP was too big, I don't think 1/2 HP would have been enough to get 48 GPM through the solar given the long lines. That 24 PSI pressure is a gauge reading on the filter and doesn't account for the suction side pressure nor the 3 feet above the ground for the gauge. When you factor all of that in, the pressure is probably well over 30 PSI so I think a 3/4 HP would have been needed. At any rate, as you point out, with a variable speed I can dial in to exactly what is required.
Just so you know, the 15 GPM is only done for the pool cleaner running on its dedicated line so isn't part of normal operation and is not used with the gas heater (turned on, that is; obviously water is still flowing through the heater). The gas heater requires a minimum of 30 GPM and will automatically shut off if the flow is lower than that. I have the flow rate set for 40 GPM when the gas heater is on (i.e. the "Gas" program on my IntelliTouch) so there should be no problem there -- the IntelliTouch lets one assign "override" flow rates for "features" such as the gas heater or solar heating.
Unfortunately, the IntelliTouch system does not let me use the solar and the gas heater at the same time (I can do so manually with service override, but not via normal operation). There are times when both could be used for a faster heating on some days. Also, the IntelliTouch uses the maximum flow rate for features and doesn't let me disable one feature when another is on -- specifically for the solar since I don't want the solar flow rate (48 GPM) to occur when the cleaner is on. I use macros to turn on/off various features to avoid conflicts, but that doesn't work for solar which is more automatic so I have my pool cleaner set to run later at night after the sun is guaranteed not to trigger solar heating.
So to sum up for flow rates, The Pool Cleaner is at 15 GPM, normal non-solar operation is at 26 GPM, gas heating is at 40 GPM, and solar is at 48 GPM.
1.5" pipe good for say 40gpm. You have 2 so lets say 80gpm if both open all the time which you say they are.
2" pipe good for about 80gpm. Both numbers more or less cap the recommended pipe velocities.
48 GPM, 3000 RPM, 1530 W, 24 PSI, 32.7% <--- this is what I normally run at when the solar is on (this is 4 GPM per panel) - This is from your list showing the high end operating parameter.
It shows the initial 1hp was too big anyways. A 1/2hp Whisperflow drawing 5.6 amps @ 230 volts would pump pretty close to 50gpm at 55' or 24psi. Since there is no 2-speed you would be stuck with that electrical bill but it would be cheaper than the 1hp.
24 GPM, 1460 RPM, 255 W, 4 PSI, 16.4% <--- I run close to this at 26 GPM when the solar is off. - This is your low end operating parameter. Smallest 2-speed would be a 3/4hp and it would still be pumping over 40gpm at 10' or 2psi. So still too big for what you need.
Hence the beauty of variable speed. In the beginning with what you show a 2-speed 3/4hp pump would have worked pretty well, but still cost more to operate. Probably a good 65-70 gpm on high through a 30" sand filter (4 hour turnover) for everything you need and around maybe 35-40 on low which would still beat 8 hour turnover.
One thing to watch out for. 15gpm you might find will not work well with your heater. I would check it out and set your lowest flow to accommodate the gas heater.
The unusually high PSI readings with both solar on and off don't match what would be seen with an analysis of head loss accounting for piping, fittings, tees and elbows, filter, heater, etc. Though the pressure gauge may be off, the problem may be due to a check valve right after the filter that says "1/2 LB. Spring" and I've been told that these are notorious for adding pressure restriction especially at lower flow rates. I'll probably get this replaced with a flapper check valve, probably a clear one not only to inspect it but to make it easier to repair if needed. I'll probably do this when my gas heater starts to go (it's 7 years old now; had one circuit board replaced as the only service needed so far) since it's only 80% efficient and we use a lot of gas to extend the season.
From the pump, flow goes through an oversized Jandy CL340 cartridge (4-cart) filter I only need to clean once a year, then optionally to/from the solar, then to a gas heater and then to the pool. I have a mostly opaque electric safety cover so my chlorine usage is low at around 1 ppm FC or less per day. The pool is used every day for 1-2 hours by my wife during the week and both of us use it on the weekends for 2-3 hours -- the swim season lasts around 7 months using gas heat for extending it (an analysis of my solar output and gas heating cost during the season is in this post).
There is a very long discussion that includes details of my piping situation, but the most relevant post summary of it is in this post. I could have saved money if larger piping was used to the solar on the roof and between panels. However, since the solar is on a one-story roof perhaps up to 20 feet high at the high point, there isn't any benefit to larger piping from the solar to the pool since pressure restriction is needed to not create a vacuum at the top of the solar if the pressure relief valve is placed there. Basically, if one wants a solar system and wants lower pump electricity costs, then one should not put the solar on the roof and should keep it at ground level using larger piping if runs are long.
The GPM, RPM, Watts, and reported PSI at the filter in my system under various operating conditions is shown in this post. As you point out, my system was a great candidate for a variable speed (especially flow-controlled) pump. The pool is 16,000 gallons and is shown here and here.
-Jeremy
Florida Leisure Pool & Spa
www.FLLeisure.com
My pump electricity costs went from $1500 per year to $750 per year so were cut in half. I have a solar system so need a higher flow rate for 12 solar panels when the solar is on, but I was able to tune the flow rate down a bit for around 15% savings there and when the solar is off the running costs dropped by nearly 85%. These large savings in absolute dollars are also due to the fact that my marginal electricity rate is around 32 cents per kilowatt-hour -- I live in California near San Francisco.
Yes, the IntelliFlo VF was much more expensive (around $1500 retail at the time, I believe), but has already paid back in savings.