If you have a swimming pool, you probably hate to see your utility bills during the summer. Chances are, you’ve attributed the high bills to your air conditioner. But pools and their associated pumping equipment might be responsible for at least as much energy use as that big central air conditioner!
Why does the pool use so much electricity and is there anything you can do about it?
Pumping water takes a lot of energy. Just think about the last time you took a swim. It takes all your energy to swim the length of the pool, while you could walk this distance without difficulty. In the same way, moving water, because of its weight and resistance to flow, requires a lot of energy.
So if moving water naturally takes energy, how can you reduce the consumption?
Without getting too technical, moving a gallon of water through pipes takes much less energy if it is moved slowly than quickly because of water turbulence. Just knowing this allows you to dramatically reduce your pool pump’s energy use.
Unfortunately, most pools are designed with vastly oversized pool pumps. For example, my pool had a 1.5 horsepower (HP) pump. This is useful for backwashing the filter, but for general filtering, using such a huge pump results in less efficient filtering and much more energy consumption. Worse, that 1.5 HP pump might pump less than twice as much water as a .5 HP pump due to the high turbulence caused by the larger pump.
You’ll find that running that 1.5 HP pump for 10 hours a day (fairly common for pool pumps) will add about 15 kilo-Watt-hours to your electric usage. For many households, that’s an increase of 30%-50% of the home’s total daily electric consumption! Over the course of a summer, that adds up to hundreds of dollars in increased electric bills.
For my pool, I installed a two speed pool pump that allows me to run at 3/8 HP for general filtering. The water flow is ample for filtering yet it uses about 1/8th the electricity as when it runs at 1.5 HP. The only time I turn it on ‘high’ is when I’m backwashing the filter. Other than that, it runs 12 hours per day at a few hundred Watts (a total of about 3.6 kWh/day). When I convert kWh/day savings (over 10 per day) to dollars, I’m saving more than $1.60/day which is about $150 per summer in saved electric bills.
If you’re building a new pool or replacing an old pump, installing a multi-speed or variable speed pump is a no brainer. At a cost of about $500 for a high end two-speed pump or $1000 for a variable speed, the savings will pay for the pump in a 3-6 years. About half that if you’re replacing an existing pump and would have to buy a new pump anyway. Pu another way, that’s like having an investment that pays 15%-30% dividends – in these economic times, you’re not going to find a better investment!
Your specific numbers will vary depending upon your electric rates. I pay a lot in eastern Pennsylvania, so any electric savings pays back quickly. If you’re in an area with cheap electricity, the payback won’t be as quick.