Exploring Green Interiors – On Demand Hot Water
It seems like everything is “on demand” these days, why not hot water for our homes, especially if it saves energy and money? Does the thought of saving an average of 20 to 40 percent on your water heating bill appeal to you? What about the storage space that you can recapture when the tank is gone? Regarding the dollar savings, Rinnai Tankless Water Heaters reports that since July 1, 2006 until today, United States consumers have wasted $12,873,198,476 by heating hot water with tanks.
Tankless water heaters supply hot water on demand, with no wait, no waste, and no tank. The compact units can supply an endless stream of hot water to multiple water sources at once without any fluctuation in temperature. Once the water tap is turned on the water travels into the unit, where heating elements instantly heat it. The heating elements are immediately shut off when you turn off the hot water valve.
Traditional water heaters continuously heating water stored in the hot water tank; energy is being lost through the vent (in gas units) and the walls of the tank. Heat exchangers in tankless water heaters are more efficient because they utilize a higher percentage of your energy dollar.
Water heater performance is rated by the U.S. Department of Energy. Performance is measured in by Energy Factor ratings—the higher the energy factor the more efficient the water heater. The EF factor signifies the percentage of purchased fuel that is used by the system to heat water. This rating includes losses through the tank as well as losses through the flue (in the case of gas-heated water). Typically, gas fueled water tanks rate at 0.62, existing older tanks are rated at about 0.55 or less, and some tankless water heaters have energy factors of 0.80 or greater.
The lifetime of a standard tank water heater is around 10 to 15 years, with proper maintenance. The longevity of a tankless unit surpasses that at 20 years or more. To select high efficiency water heating equipment, compare the Energy Factor information provided by the manufacturers. Tankless water heaters on the market today use gas, electric, or solar energy.
In determining the type of tankless water heater suitable for your application, consider these factors: fuel type, location, size of home, demand, and application.
Typically gas water heaters heat a larger volume of water each minute than electrical units. Gas heaters typically have the capacity to heat 4 gallons of water per minute to the output of electric models at 3 gallons of water per minute. This is an important factor if you want to provide hot water simultaneously to several plumbing fixtures. Four gallons per minute is equivalent to about 2 showers running simultaneously.
Solar water heaters almost always require a backup system for cloudy days and increased demand. Solar systems performing at their utmost capacity should be installed on a south-facing location. Commercial solar water heaters have a larger thermal storage, heat exchanger, piping system, and a solar-powered back-up heater that ensure that hot water demands are met, even if the weather is not sunny.
Solar Water Heaters are not the best option for cooler climate areas.
Cost is also an issue when deciding whether it’s time to move to a tankless water heater. The cost varies depending on the unit’s capacity, energy efficiency, and type. Typically, traditional tank water heaters cost anywhere $100 to $600 for electric units and $250 to $1,000 for gas units. Tankless water heaters vary from $200 to $1,200. Solar water heaters run range in price from $1,000 to $5,000 (including installation). When you weigh the cost of the units to the monthly savings over the life of the unit, the more expensive tankless units generally prove to be the most economical over the unit’s lifetime.
For 2009, the Federal Tax credit is $300 for all whole-home gas tankless and gas condensing models. The Energy Star criteria states the Energy Factor must be greater than 0.82 for a whole home unit and 0.8 for a gas condensing unit. Energy-Star qualified high-efficiency gas storage water heaters do not qualify for the tax credit. There is presently no tax credit provided by the State of Tennessee. For tax purposes, you will need to save your receipt and the Manufacturer’s Certification Statement.
—By Cameron Austin of Beth Haley Design
Editor’s Note: Beth Haley Design, an urban interior design firm, assists clients with all phases of renovation, remodeling, new construction, and décor. Haley has won awards from the Tennessee Chapter ASID (American Society of Interior Designers). She is a member of ASID, ASID Sustainable Design Council, HGTV Designers Portfolio, Home Builders Association Remodelers Council, National Kitchen and Bath Association (NKBA), and the USGBC. E-mail your questions to her at firstname.lastname@example.org. or visit http://www.bethhaleydesign.com.