Tuesday, November 21, 2006

Save on Hot Water

source: http://sustainabledesignupdate.com/?p=61

GFX Heat Exchanger

We are working on an energy efficient renovation to an all electric house in Florida. In addition to using renewable energy we are looking at greatly reducing energy use. One of our energy saving strategies is to use a waste water heat exchanger. These devices efficiently pull heat out of waste water and put it into the water heater.

Excerpeted from Rocky Mountain Institute â€Å"Home Energy Briefs #5”

In the average home 80–90% of the energy used to heat water goes down the drain. A water based heat exchanger can capture a lot of the heat in drain-water and put it to use pre-heating the water going in to your hot water supply . One type, called a â€Å"gravity film exchange drain-water heat recovery system” has been found to save 25–30 percent of total water-heating energy. This technology is compatible with all types of water heating systems, but it is especially suitable with on-demand water heaters and solar thermal systems. Prices range from $300–400 and paybacks are in the range of 2.5 to 7 years, depending on how often it is used. For more information on this technology, visit www.gfxtechnology.com.

From the GFX Technology Website:

Perhaps the most important and immediate benefit to owners of all-electric homes is GFX’s power-boost; enough to triple the shower-capacity of tank-type water heaters and halve the cost of a shower. For example, if GFX boosts cold water temperatures by 30 degrees, it’s feeding back about 10 kW of power; more than enough to triple your family’s showering-time and save 2 kW of energy per 12-minute shower. This means if you pay 8.5 cents to 17 cents per kWh for electricity and your yellow water heater sticker shows an efficiency rating (energy factor) of 85%, GFX could save you 20 cents to 40 cents per shower, depending upon where you live and type of showerhead installed.

GFX gives an electric water heater the capacity of a gas heater. In fact, when tested with GFX, the first hour rating of two types of high efficiency 50-gallon electric water heaters tripled to 180 gallons; more than “double the capacity of typical 50-gallon gas heaters” â€" with an energy factor rivaling that of a heat-pump, plus unsurpassed reliability and quietness.

According to U.S. EPA standards, if just 6 million electric water heating systems were to be upgraded by GFX, carbon dioxide emissions would drop by more that 20 million tons per year; the amount released by burning 1.8 billion gallons of oil.

All-copper construction means GFX will last as long as your plumbing system and will pay for itself many times over. Safety is guaranteed by U.L.-approved, double- wall-vented construction and self-cleaning ensures maintenance-free operation at peak efficiency. The falling-film heat exchanger models listed in the table below have ultra-high heat transfer coefficients required for compact size and high capacity.

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