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| Heating water can be a tankless job |
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| Home & Building |
| Written by Jean Starr |
| Monday, 30 June 2008 16:34 |
 You wouldn’t heat a pot of water on the stove just in case
you wanted to cook something later. So, why keep a huge
tank of water hot just in case you need it? It’s an analogy
John Brooks of Lone Star Custom Homes in Carmel, Ind.,
uses when describing the benefits of tankless, or on-demand
hot water heaters.“They’re not heating water 24 hours a day. They just heat it when it’s needed,” he said. “(The water) gets up to temperature in about 10 to 12 seconds.” According to the U.S. Department of Energy, for homes that use 41 gallons or less of hot water daily, on-demand water heaters can be 24- to 34-percent more energy efficient than conventional storage tank water heaters. For homes that use around 86 gallons per day, demand heaters can be 8- to 14-percent more energy efficient. To save 27 to 50 percent, install demand heaters at each hot-water outlet. 
Illustration source: U.S. Energy Partners
Demand water heaters typically offer a flow rate of two to five gallons a minute. Gas-fired units produce higher flow rates than those powered by electricity. Choosing the right demand water heater, or installing more than one unit will assure that it can keep up with household needs. “Both storage and demand type heaters are impacted by the distance water must travel to its use,” prompting some to install more than one in their home, said Stan Wash, service manager for Young Plumbing in Valparaiso. “For instance in a very large home they might have one at each end of the home.” They are more costly to purchase and install, but demand heaters have a life expectancy of more than 20 years. They also have easily replaceable parts that extend their life by many more years. In contrast, a storage water heater lasts 10 to 15 years. Brooks installs tankless water heaters in all of the new homes he builds. “I wouldn’t know of a reason they would not be used,” he said. “It might cost a couple hundred more. They don’t rust. They don’t fail.” They also are modular with component parts that are easy to service. Although the technology has been used for many years in Europe, the United States lags, with tankless water heaters installed only 10 to 20 percent of the time. Brooks recommends using trained installers for the work. “We’re certified installers, but (certification) is not required in Indiana.” Although tankless heaters are available through builders-supply stores, installation is not necessarily a DIY project. Brooks said several problems could arise from improper installation. “The biggest are situations where a tankless heater is mounted on a wall and vented horizontally but not at the right angle,” he said. Condensation appears outside the tank, which can collect on the burners and rust them out, or gas may leak into the house. Wash has seen his share of improper installations, too. It’s not something that can just be thrown onto the wall. “We often have to re-pipe the entire home and it sometimes requires a new gas meter installation,” he said. Another expense is the tankless heater has to be connected to a specially sealed stainless vent pipe because it gets very hot. Regardless of the type of water heater you have, you’ll stand there and wait for the water to heat, Wash said. And this is where the digits meet the lingo. First, there is the flow rate, measured by gallons per minute of water that needs to heat to the desired temperature. To put things in perspective, the Federal Energy Policy Act requires all faucet and shower fixtures made in the United States to have a flow rate of no more than 2.2 gallons per minute. The flow rate is dependent upon the desired temperature rise. The more slowly water flows through the unit the more the water can be heated. For instance, if the input or ground water is 50 degrees F, and you want to take a shower with 110 degree F water, the temperature rise would be 60 degrees. Tankless water heaters are sized by their temperature rise at a given gallons-per-minute. And the more they are put into use, the more engineering and technology has influenced their development, including a hybrid. Called Eternal, it is an ondemand system that produces an endless hot water supply similar to tankless units. And yet the Eternal also performs like a traditional tank system with improved efficiency, better reliability and no worries of cold-water shock. In fact, this hybrid water heater will generate a first hour output rate of more than 300 gallons and is recirculation ready. Features to look for in a tankless water heater:
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About the author Jean Starr
Jean Starr is a freelance writer from Chesterton, Ind., who writes on many topics, including the environment.
Jean Starr is a freelance writer from Chesterton, Ind., who writes on many topics, including the environment.
