Most homeowners who’ve invested in a backyard swimming pool are looking for ways to enjoy the season longer without significantly raising their utility bill.
Southern Californians are spoiled in that regard. Swim season runs from early April to as late as Thanksgiving because temperatures rise so much during the day in spring and fall, says David Penton, CEO of Fluid Dynamics Pool and Spa in Fullerton, California. Pool heating is popular in his high-end market to keep the water cozy in those long shoulder seasons. “I don’t know that I’ve ever built a pool without a heater in Southern California,” he says.
Until a few years ago, heating a pool in much of the United States to the optimum 82 degrees either took a long time or cost a lot of money. But now there are options for high-performing heaters, especially for people using propane. These technologies can help pool customers swim laps later in the season — and for less money.
In 2015, Raypak introduced the propane- or natural gas–fueled X94 Professional series 399,000–British thermal unit (BTU) pool heater, which has a 94 percent thermal efficiency and a stainless steel heat exchanger that withstands the corrosive effects of pool water. Marketing manager Terry Doyle says that only in the last few years has the industry made the leap from 84 percent efficiency.
“For anything above 84 percent, you have to condense the flue products, and it requires a whole other combustion device to do that,” he says. “You have to switch from the traditional thin copper tubing to something that will resist the acidic flue particles.”
Last year Pentair Aquatic Systems introduced another high-efficiency option, the ETi 400 High-Efficiency Gas Heater, which is 96 percent efficient and can be converted to propane with a kit. “It’s the first ever to use titanium inside the heat exchanger for corrosion resistance,” says Azur Dzindo, Pentair’s global product manager for heaters and lights.
Gas, Heat Pump, or Both?
While heat pumps are super-efficient at maintaining pool temperatures, their pain point is the long lead time they require to bring the water to a comfortable temperature, and they don’t perform well in cold climates.
“With an electric heat pump, you have to turn it on Monday so the pool will be ready for Saturday,” says Nikki Oakley, construction manager of Anderson Pools and Spas in Murfreesboro, Tennessee. Solar also presents challenges. “We do use solar heating when we have the opportunity, but it’s harder in new-home neighborhoods because the roofs are chopped up; you can’t put solar up there efficiently.”
Because gas heaters heat the pool faster, Oakley says, they can be turned off to save energy when the pool’s not in use. When it’s pool time again, the gas heater can quickly bring the water up to temperature.
Propane and natural gas heaters are speedier because they have a much higher output than heat pumps — 400,000 Btus is a traditional residential-size propane or gas heater, while the biggest electric heaters are just over 100,000 Btus, Penton says. That means it takes roughly four times as long to heat the water with electric.
Hybrid pool heaters offer an option that combines the rapid heat rise available with propane or natural gas along with the temperature maintenance efficiency of a heat pump. Later this year, Pentair has plans to release the Ultra-Temp ETi Hybrid Heater with 230,000-Btu output. A 320,000-Btu hybrid heater will follow in 2018. The hybrid components are housed in one cabinet with a single-connection inlet and outlet for easy hook-up.
“The heat pump needs 7 kW/hr to run, and the heat pump control board chooses fuel priority based on heating demand,” says Tom Schoendienst, Pentair’s automation specialist. “The more temperature rise needed, the more it will turn to gas heating.” Users can also choose to switch to gas heating for temperature maintenance if the cost of electricity rises.
As more and more customers become energy aware, Penton says, the availability of high-efficiency products from several manufacturers is a boon for builders, who can pick and choose based on their preferred manufacturer’s service or warranty. And homeowners can enjoy their pool without seeing their heating dollars spiraling down the pool drain.