By Chuck Ross
For the environmentally conscious—and fiscally conservative—homeowner, few experiences are more frustrating than watching perfectly good water go down the drain while waiting for hot water to arrive at the tap. And, with houses getting bigger and bathrooms getting farther away from the hot-water heater, the amount of water wasted while waiting for hot water to emerge from the faucet is growing every year.
Just how much water is wasted in any given household can vary, based on factors such as whether hot-water pipes are insulated and the distance to the farthest water fixture from the hot-water heater. However, the California Energy Commission estimates households can waste five to 20 gallons every day—or 1,825 gallons to 7,300 gallons per year—waiting for hot water to arrive. Even using the minimum estimate per household, that amounts to nearly 200 billion gallons down the drain unnecessarily every year in the United States alone.
However, there are other options for addressing this waste, and hot-water recirculation systems are one that's gaining fresh attention. Some communities, such as Scottsdale, Ariz., are offering rebates for installing these systems in an effort to boost water conservation. The systems force hot water to the tap and cold water back to the hot-water heater instead of down the drain. They are gaining popularity with the addition of new control systems that enable on-demand functionality and improve systems' energy efficiency.
Hot water, instantly
The appliances incorporate a thermostat, typically at the plumbing fixture farthest from the hot-water heater. When the water temperature at that location drops below a fixed set point, a pump kicks in to push fresh hot water to the pipe, while a bypass valve at the fixture allows cooler water to be forced over to the cold-water line and back to the water heater.
Recirculation designs have been around for years, experts say. However, they note, earlier systems operated continually, circulating hot water throughout the day, even when it wasn't needed.
"They were great from a convenience standpoint and terrible from an energy standpoint," says Shawn Martin, director of applied technology at the National Association of Home Builders Research Center. "These are definitely waning."
Boosting control
Newer offerings use either timers or direct controls to operate the pump. Timers can be set to run systems automatically during high-use periods, such as during the morning shower rush. Direct controls include simple push buttons at the fixture, as well as more advanced occupancy sensors that activate whenever someone approaches the connected fixture.
The big decision with either approach is where to place the pump: at the farthest fixture from the hot-water heater or at the water heater itself. Shawn says a central pump at the water heater may need to be larger and use more energy than fixture-based pumps. However, homeowners may lack required space and electrical connections at the local fixture, making the water heater a better option.
Additionally, with new construction, homeowners may choose to connect the bypass valve to a dedicated return line to the water heater, eliminating the need to force warmish water into the cold-water system.
Easy installation
Installing hot-water recirculation systems poses few problems, say those familiar with the process.
"The installation is pretty straightforward," says Tim Bentley, owner of Phoenix-based Intelligent Plumbing Solutions. "There's not a lot to mess up. The biggest thing is being careful with the flexible tubing so you don't kink it. The only other thing is not putting in the bypass valve backwards."
The ease of installation and relatively low cost of these systems prompted Scottsdale, Ariz., officials to begin offering rebates in August 2005 to residents buying the equipment, according to Elisa Klein, water conservation specialist with Scottsdale's Water Conservation Office. By mid-December, 346 rebate requests had been submitted to the office, she says.
"We've had three articles in the newspaper, and that's prompted a great reaction from citizens," she says, adding that residents are reminded of how much water they waste every time they turn on a hot-water faucet. "It's a very visible problem that homeowners can see themselves."
Chuck Ross is a freelance writer based in Brewster, Mass., who frequently writes about topics related to construction technology.
| 
