Heating and Cooling a Pool
A unique heating/cooling system provides for a refreshing dip
This Old House TV: Key West house project
Key West homeowner/architect Michael Miller wasn't all that keen on putting a swimming pool into his minuscule backyard. "I would have been quite content to sit in some hot tub around the side somewhere," he says. Fortunately, for him and This Old House, his was not the only voice on the project: his wife, Helen Colley, is an avid swimmer, and there was no question what was going to happen out back.
Excavator Ray Vanyo was one of the first subcontractors to appear on site, slowly but surely removing enough soil to squeeze a 35 x 11 pool in. Hitting "capstone," the oolitic limestone underlayment of the Keys, is Vanyo's usual worry. Here, however, the digging was easy, the theory being that the area was an ancient sinkhole. Whatever the cause, a previous owner had taken advantage of the same condition, constructing a massive concrete cistern underground. Breaking it apart was easy, though achieving the nine-foot deep-end depth Colley wanted proved a challenge in the constricted space.
As seen on the show, the next step was lining the pit with reinforcing rod, attaching a wire-mesh and fabric substrate to it and spraying on a thick coating of concrete. A member of the concrete crew formed and hand-troweled a flight of steps, and later a separate artisan applied a white finish coat that contained specks of blue. Colley chose a ring of beige-pink tile for the waterline, and the combination is a winner. "The blue-white of the coating makes the water look especially fresh and cool," says Miller, "and the tile accentuates the effect, really making it 'pop'." Can you tell that he's beginning to come around?
Local pool equipment purveyor Gilda Fernandez specified two important machines. One, the water filter, uses diatomaceous earth as a medium to remove foreign matter down to the micron level. (Appropriately, the stuff is a product containing the silica skeletons of diatoms, unicellular plankton of the kind that abound in the ocean around Key West.) The other, a heat pump, draws heat from the air to warm the water; just as importantly, it can reverse the process to cool the pool. "Without that feature," she observes, "water temperatures can get up around 95 degrees down here in the summer." Hardly a refreshing dip. With it, she thinks Miller and Colley will be able to drive their pool down to a coast-of-Maine 60 degrees, if they're so inclined.
The pool cost Miller and Colley around $25,000 to build. It holds a bit over 17,000 gallons and costs about $100 to fill. Its nine-foot depth makes it one of the deepest of the island's approximately 800 pools. It acts like a back room for the house, separating it from the line of palms that mark the rear of the property. Lit up at night, it bathes the palms and back porch in a soft blue glow.
Colley swims 25 laps at a time; Miller admits to petering out at five. "Aside from skinny-dipping," he reports, "one of the things I love about the pool is how big our house looks when I look at it from down at water level." Now there's a perspective no hot tub could offer.