The Low Down On Green Living
June 8th, 2009
Water heaters may not be the sexiest energy device out there, but they’re certainly important. In a typical home, they account for 20% of energy use, and even more if you live in a warmer climate (average of 35% in California, for instance). And there’s a major difference between the most and least efficient options, so making the right choice for your budget/household is important. The most efficient combustion heaters can save 50% compared to standard models, while a solar water heater could cut 80% or more from your annual water heating bill (you can find out how much they’ll save in your home by selecting various water heating options using our Environmental Impact Calculator. It covers tankless, high-efficiency storage and solar hot water heating options).
Over the past few years, the upper end of the performance spectrum has been pushed outwards, and the latest entrants from Navien set a new high. Standard storage water heaters routinely exceed 60% efficiency, manufacturers such as Takagi and Rinnai have pushed tankless water heater efficiencies over 80%, and AO Smith has introduced tank-based versions exceeding 90% efficiency.
All of these are well below the performance of the Navien CR line of tankless water heaters, which top out at a whopping 98% efficiency! This means that 98% of the energy contained in the natural gas (or propane) fuel is converted into hot water and only 2% is wasted. How do they do it? The Navien CR units use a number of tricks to get this performance:
- Advanced heat exchangers, which transfer heat from the burners to water;
- Condensing heat exchangers, which capture heat by condensing water vapor in the flue gases into liquid (by releasing the latent heat of condensation); and
- Sophisticated microprocessors that continually ensure that the mix of oxygen and fuel in burners is optimal.
Another cool feature? Many models come with a recirculating pump and small buffer tank, which not only keep some hot water in the system at all times but also reduce the starting flow rate to 0.1 gallons per minute, a flow rate exceeded by even the most thrifty of faucet aerators. No more slugs of cold water in the shower with these units!
If you’re intrigued, then here are some answers to your next questions:
- Where can I get one? Strangely, Navien doesn’t have a directory of local installers on their website. I’m sure you can find one easily, though, by calling the numbers on this page.
- How much do they cost? Pricing information isn’t readily available, but according to an interview with an installer in this article from Building Green (subscription required), installed prices are comparable to other higher-end tankless options. The unit costs a bit more, but because of the condensing feature the venting system can be made from plastic rather than stainless steel. These units will likely qualify for the 30% tax credit for high-efficiency water heaters.
- This company is relatively new in the US (2006) - can I trust them? As with any long-lasting high-end home purchase from a new company, it might be wise to wait a bit until all of the kinks are worked out. Navien offers a 15-year warranty on the heat exchanger and five-year warranty on all other parts, though, which are among the tops in the industry. Navien is part of a large Korean manufacturing company that’s been around since 1978, so they’re clearly in this for the long haul.
Thanks to Building Green for the article that brought this to our attention!
Popularity: 6% [?]