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| 11-08-2008 4:40:04 PM - 6 Comments | Posted By: Alan Meier |
| November/December 2008 Editorial: Heat Pump Water Heaters—Another Prius in the Basement? |
 It was good news to learn that Energy Star has finally announced specifications for water heaters. The specification for heat pump water heaters is particularly welcome, since these products have an unusually large savings potential. A heat pump water heater can reduce water-heating energy by half, which translates into over 1,500 kWh per year in many homes. Nearly 40% of American homes use electric water heaters, so the market is huge. This market is unlikely to be tapped soon, however, because there are no significant American manufacturers of heat pump water heaters. This situation is likely to change, since major refrigeration manufacturers—GE, for example—have announced plans to begin production.
Rapid progress? Not really. Japanese manufacturers are already producing half a million heat pump water heaters a year (see “A Cute Water Heater,” p. 12). You can be sure they are looking for export opportunities. Have American manufacturers missed an opportunity and allowed another “Prius” to dominate the market? To be sure, the Japanese ECO-CUTE heat pump water heater has some attractive features. First, it has a remarkably high reported efficiency, with a seasonal coefficient of performance (COP) approaching 3. The few existing U.S. models have achieved only a modest COP 2, so the ECO-CUTE squeezes 50% more hot water out of each kWh consumed. Second, the ECO-CUTE uses CFC-free CO2 as the refrigerant. Thus the ECO-CUTE is doubly green, by combining efficiency and zero CFCs. Is there a downside? You bet; these suckers are expensive, at over $6,000 in Japan.
How do Japanese consumers justify buying a million of these expensive products? The answer is a useful lesson in economics and culture. First, Japanese homes use lots of hot water—more, in fact, than most American homes. Nearly all of it goes to the famous Japanese baths. Second, the ECO-CUTE can also provide hot water to an in-floor heating system, which fits in particularly well with the Japanese lifestyle. Third, the ECO-CUTE is designed to operate only at night and during periods when electricity is cheap. ECO-CUTE owners get a special tariff, which is far below the normally very high residential electricity rate (about 24¢/kWh). Thus the cost savings are substantial. Combine that with a $420 government subsidy to purchasers of ECO-CUTEs, and the payback time drops from centuries to under a decade.
The environment in the United States would appear to be less favorable to sales of the ECO-CUTE. But this could change quickly. For example, modest redesigns might lower the cost without sacrificing all of the efficiency advantage. And one of the new energy bills being contemplated in Congress could easily add a tax credit for heat pump water heaters. Suddenly, there’s another Prius in the basement.
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| Date & Time |
Comment |
By |
11-18-2008
9:51:23 AM |
The US will more likely mimic Europe than Japan. Expect solar water heaters – especially flat plate collectors – to grow by 8 times in the US over the next 5 years. |
Seth Warren Rose |
11-18-2008
6:51:25 PM |
HPWH's do in fact work as advertised. I installed one of the retrofit models on my own electric hot water tank and it's working spectacularly well. I have a large basement utility room with some slight humidity issues and the slight dehumidification effect is working well to keep it dry as well. Though it wouldn't work for any substantial humidity issues because our hot water use is too low, but it is a nice supplement.
To monitor its use, i never reconnected the power to the primary water heater, so I'm running 100% on the HPWH. Using a Kill-a-watt PRO to monitor use for our family of two, it's projecting about 51kwh/month, considerably below what I would have computed. Granted, we don't use a lot of hot water, but neither do we deprive ourselves.
Given the standby losses from most oil fired boilers of 1/4-1/2 gallon per day (30-60kBTUs or 8-16 kwh), the savings are remarkable.
While the retrofit units may not be ready for the mass market due to installation concerns (the manual says you have to replace the sacrificial anode every 6 months!) I look forward to upcoming integrated units. I think the potential here for tremendous energy savings are excellent. Multiplied by millions of water heaters, we're well on the road to profound savings.
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Theodore Inoue |
11-30-2008
5:12:32 PM |
As a profesional home energy auditor in San Diego, this is good news. Many of my customers look for ENERGY STAR recommendations for all of their upgrades and now we'll be able to offer one for water heaters. |
Home Energy Audit Technicians |
12-29-2008
3:21:41 PM |
HPWHs are already here. AirGenerate, a US-based company has garnered a lot of interest lately. They are already working with dozens of utilities and claim to be the largest HPWH manufacturer in USA. Their retorfit model (AirTap) is priced at $699 and qualifies for $300 tax credit from IRS. At 68 degrees, their COP is 2.11. They are launching an integrated model soon as well. I saw them at West Coast Green and installed their unit few days later. The savings are unbelievable. The payback is less than 2 yrs, can work with any existing water tank, uses 110v, etc. If interested, check them out at www.airgenerate.com. |
Greg Chibowski |
03-31-2010
6:02:18 PM |
Look carefully at the specs beofore buying one of these non Eco Cute HWHP because their operating range may only start at 42-45 degrees F. This is a down side especially in more moderate climates. If your water heater is in your house and you need cooling, then great. But otherwise, you don't want to cool your house when your are simultaneously trying to heat it. The Eco Cute uses an air-to-air unit to capture the free energy in the outside air to heat your hot water. Great idea if they have perfected it. Why isn't USA doing it? Big oil and other US HVAC industries are afraid they will be cut out of the market? |
EWnergy Conservation Technician |
04-04-2010
11:30:14 AM |
As a profesional home energy auditor in San Diego, this is good news. Many of my customers look for ENERGY STAR recommendations for all of their upgrades and now we'll be able to offer one for water heaters.
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TreeFrog Energy Auditor |
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