Gary Walker was stunned when he found out how much it would cost to heat his soon-to-be pool.
Already he was paying about $1,200 a month to power his eastern Canadian home — and that was before the local utility installed smart meters so it could charge more for peak-hour usage. Now his pool builder, Barry Justus, explained that it would probably cost $1,000 to $1,500 per month to run an indoor pool and its natatorium.
“We didn’t want to back up from building the pool, but we didn’t want to spend that much per month heating it,” Walker says. “So I started looking for alternative ways to do it.”
Natural gas wasn’t an option, and the renovation cost of switching from electric heat to an oil burner would be cost-prohibitive. “Even propane wasn’t really feasible, because propane is an inefficient fuel,” Walker says. After some research, he decided to install a geothermal system to heat his home and indoor pool.
He’s been very satisfied with the results. “The problem we’ve run into, which isn’t a very bad problem, is that the pool is almost too warm sometimes,” he says. “It’s basically between 88 and 90 degrees, and the air is generally 84 or 85 degrees.”
As for those monthly utility fees? “Our electricity bill is down around $700 per month for the whole [property], and the pool probably eats up $300 of that,” Walker says.
As important, he expects the geothermal system to pay for itself in about seven years.
While geothermal technology is pricier than most options, it can fit the bill for those with the right combination of budget, conditions and environmental concerns.
Geothermal technology may very well be the most efficient.
That’s what the Department of Energy concluded in 2008. It had released a tax-credit program in 2005 for solar systems and fuel cells, ignoring geothermal entirely. “They went back and incorporated it in, and one of the things they said is that it’s the most energy-efficient way to heat and cool a space,” says Mike Geremia, president of Geremia Pools in Sacramento, Calif., who installs his own proprietary geothermal systems.
The green aspects are easy enough to understand. The system involves transferring heat or cold from the ground via insulated plumbing lines filled with a liquid — typically water mixed with ethanol or methanol — and running to a heat exchanger. Unwanted heat or cold is then taken from the pool or home and back to the ground.
“It’s like found energy if somebody converts to it,” Geremia says.
As green alternatives become more appreciated by utilities and government agencies, they can pay off in other ways. In California, for instance, it can help real-estate values. Geremia reports that properties in his state are appraised 5- to 9-percent higher if they have energy improvements such as geothermal. “Obviously the lower energy improvements of weather stripping, insulation, maybe windows don’t carry quite the value that solar and geothermal will,” he says.
Another builder appreciates the fact that the heat exchanger never makes direct contact with chemically treated pool and spa water, which stays contained in pipes traveling through the exchanger.
But geothermal isn’t meant for every customer. There’s the issue of price. Exact costs depend on drilling rates in the area, but conventional geothermal systems generally run in the tens of thousands of dollars and can surpass $100,000.
The time it takes for geothermal heating systems to pay for themselves depends on local conditions — both installation and utilities charges in the area. “This kind of product may not have a big market if you’re in a place like Seattle, where they’re driven primarily by hydroelectric power,” Geremia says.
But experts say they last. In a well-made system, the heat pump is the first thing to need replacing. But those often are rated to last 13 to 24 years, Geremia says.
Builder Barry Justus, who works with a local geothermal contractor to add the technology, will recommend it to his high-end customers if they don’t have access to less expensive forms of fuel. “Natural gas is very inexpensive for now and the foreseeable future, especially because of the new technology, the fracking,” says the president of Poolscape Inc. in Burlington, Ontario, Canada. “But if the client is relying on propane, oil or electric heat for their house, then we’ll go geothermal.”
Steve Hamoen, the geothermal contractor who installed Walker’s system, said his products are especially complementary with indoor pools and spas and the climate control systems used for the enclosure. “You’re always going to get a larger payoff for an indoor pool because your consumption rates for energy are going to be higher,” says the president of Zonelife in Cambridge, Ontario, Canada. “Because not only do you have to manage heating, you also have to manage cooling an indoor pool and humidity.”
It becomes more cost-effective when the home is being built at the same time. This way, the drilling can take place for both abode and pool, making the pool part proportionately less expensive than if it had been done separately.
For the builder, the main role is to prepare the pool to be as efficient as possible and work with the geothermal contractor.
“We do all the insulation of the pool, the decks and the bunker system,” Justus says. Walker’s pool, for instance, has 2 inches of foam under the floor to ensure that none of the radiant heat is wasted. “The [work] on our end is basically hooking up to the heat exchanger. So [geothermal installation] is mostly separate from us, other than bringing the geothermal contractor in and being the liaison for the project management.”
The systems can be paired with radiant heating, which is particularly effective inside. “An indoor pool is typically kept at the same temperature all the time, so it becomes very efficient to put infloor heating in the base of the pool,” Justus says. “It’s a slow way to heat a pool, but it’s efficient.”
How geothermal works
Geothermal systems contain two sides — the source side, where the heat is gathered; and the load side, where the heat is transferred and sent to its destination. The load side includes the buried piping and is where most of the cost is incurred.
There are four basic ways of configuring the lines. The least expensive method is to dig trenches and install the plumbing in a horizontal loop that moves away from the heater, then comes back. But this requires a sizable amount of of land — the lines must run about 300 feet for every ton of heating or cooling, Hamoen says — so it generally won’t work for the average 1/4-acre lot.
“[Our system] took up an acre and a half of our property,” Walker says. “We had 12 600-foot lines, which gave us about 12 tons of capacity.”
If this method is used, crews typically set the lines 4 to 5 feet below ground. Hamoen, however, prefers to place them 8 feet under. This serves two purposes: It gets plumbing out of the way of the frost line, and it takes advantage of the more stable temperatures found the farther down you go.
If the property has a pond, crews can place lines on the floor of the water body, forming a pond loop. Here, heat or cold can be gathered from the water and taken back to the home and pool. This often is the next least expensive after the horizontal loop, because it doesn’t require drilling or digging.
If space on the property is limited and there’s no pond, crews can drill down and install a vertical loop. Here, the lines go down 250 feet per ton of heating or cooling, Hamoen says. In many areas, this is the most expensive method. But price generalizations can’t be made, since local drilling rates vary widely. “For us, it cost $20 per foot last year [to drill],” Hamoen says. “But in Winnipeg, it cost $7 or $8 per foot. So sometimes for them drilling is actually less.”
The previous three methods are all closed-loop systems, in which the fluid is continuously recirculated. The fourth type is called the open loop: Crews dig a well, then run open-ended plumbing lines down to groundwater. Here, well water replaces the fluid used in the other systems. It is pulled from the well through the end of one pipe, and travels through the lines to the heat exchanger. Once the temperature transfer takes place, the water is sent to another location and exits out another end of the pipe.
This system is only suitable if there is plenty of groundwater that maintatins a relatively consistent temperature. To determine the constant availability of water, a 24-hour drawdown test must be performed. “That basically proves that you can have the needed flow for 24 hours,” Hamoen says.
If the well sits close enough to the ground, an open loop can be more cost-effective, since it doesn’t require drilling too deep and only one hole is needed, as opposed the few needed in a vertical loop.
Costs aside, this system can also prove the most efficient of the different methods. “I typically call the open loop the Ferrari of the systems, because when it works, it works amazingly well,” Hamoen says. “You’re typically guaranteed the best entry water temperature into the unit, because you’re seeing a new molecule of fresh water every time. So you’re always going to get that 50- to 60-degree entry-water temperature.”
However, there’s also the not-so-flattering side of the Ferrari analogy. “We all know Ferraris are expensive when they break,” Hamoen says. “If your well pump goes, that’s an expensive fix, and if your well dries up, now you have a problem.”
Hamoen has also installed a fifth, more specialized, system that can be used in rare situations. Called a process loop, this works when there are two water elements situated near each other that have directly opposing temperature needs. On one property, for instance, a resort had a spa and chill pool right next to each other. One needed to be hot, the other cold. “We put the geothermal unit right in the middle of those,” Hamoen says. “It’s a geothermal heater but it’s not tied to the ground — the ground is the other pool.” The cooler temperatures rejected by the spa went to the pool, and the warmer temperatures transferred from the pool to the spa.