Radiantly Warm Swimming

Custom Home Outdoors Magazine

In-Floor Heating Adapted for Pools
By Rebecca Robledo

Innovation doesn't always mean reinventing the wheel. Sometimes it's just finding a new way to use an old product. That's what Michael Giovanone, president of Latham, N.Y.-based Concord Pools, did. The 34-year veteran pool builder constructs some of the most stunning vinyl-liner pools in the country, many with vanishing edges.

Both pool and custom home builders can appreciate one of his most recent accomplishments. Giovanone has taken a technology that the home industry has used for years now and applied it to his swimming pools.

These systems are famous for heating indoor flooring, driveways, and patios. When building his own house a few years ago, Giovanone even used radiant heat under his bathtub, so the surface wouldn't be so cold when his wife used it. He then decided to try the technique on pools and eventually perfected his own system. Giovanone found that radiant heat warms up his pools efficiently.

Botton to Top When a radiant heat system sends a hot liquid water or antifreeze through tubing embedded in the concrete pool floor, the liquid heats the tubing, raising the temperature of the concrete to about 100 degrees F.

Unlike a standard pool heater, the radiant system warms the water evenly from the pool floor all the way to the surface, maintaining a consistent temperature from bottom to top. There is no thermal layering of heated water, Giovanone says. If you jump in a pool that's 10 feet deep, your feet are the same temperature as your shoulders. Operating independently from the pool's filtration system also saves energy costs, since heating the pool doesn't require turning on the circulation system.

As a concept, radiant heat is older than many of us realize. Why, out in the Old West, did they put rocks around their campfires, Giovanone asks rhetorically. So when they went to sleep and the fire went out, the rocks still kept them warm. Radiant heat was on the plains back in the 1800s, when the cowboys slept around cobblestone-lined fires.

These systems work best for frequent swimmers, since it takes two to three days to raise the water temperature from the low 50s to the high 80s. Once the water is close to the right temperature, the heater can achieve a 1-degree rise in about two hours, Giovanone says. It's set on a thermostat, so when the water reaches the right temperature, the system maintains that temperature at a rate more efficient than regular pool heaters, according to Giovanone. The system can be used with most on-the-market controllers.

Gas, propane, or electricity can fuel a radiant heat system, which can be hooked up to a home's boiler. And since they're used at different times of the year, the home and pool heaters will rarely need to run simultaneously, Giovanone says, so you won't tax the boiler system.

Giovanone and his crews assemble these systems using several components from the local heating supply house. It starts with a tankless water heater, which heats the antifreeze instantaneously as it passes through a copper heat exchanger. The space-saving unit measures about 2 feet by 3 feet, weighs approximately 50 pounds, and can be mounted on a wall. Giovanone believes they last longer than a tank system, partly because they don't accumulate mineral deposits.

Polyethylene cross-linked (PEX) pipe carries the antifreeze through the pool floor. Water temperature is monitored by a sensor placed in the pool plumbing that's connected to the thermostat. A circulating pump sends the antifreeze through the system, and an expansion tank is installed to hold any residual antifreeze when it expands from the heat.

Comfortably Efficient In addition to being more efficient, radiant heat systems offer other benefits. They aren't vulnerable to damage from chemically treated water. And since the system uses antifreeze, it doesn't have to be winterized. Giovanone likes the fact that he can begin heating his pool before he even opens it. You just turn on the radiant heat system, start melting your ice before you even uncover the pool or take the plugs out, and add a month to your swimming season, he says.

Unlike traditional pool heaters, which rely on inlets to feed warm water into the vessel, these systems don't stir up the water. This reduces the surface-to-air ratio that can sap pools of their heat. In a 16-by-32-foot pool, for instance, a ½inch ripple can increase the surface exposed to air from 512 to about 800 square feet, making it easier for heat to escape. Here, rippling is reduced or eliminated altogether.

The lack of turbulence also keeps the water glass-smooth on a vanishing-edge pool a benefit that Giovanone didn't expect. With radiant heat systems, everybody wins. Giovanone charges from about $6,000 to $9,000 for these systems, compared to the $1,800 to $2,000 that he gets for regular pool heaters.

This system requires two basics. First, a concrete floor thick enough to accommodate the pipe without compromising structural integrity 3 to 4 inches for vinyl-liner pools. Second, it should be installed by a crew that routinely does customized work. It took Giovanone about 10 hours to train his workers. Now, an experienced two-man team can install the heating system in about four hours.

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