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Tankless Water Heaters: Latest in High-Efficiency

Basement, Bath, Energy Efficiency, Plumbing, Plumbing - Directory, Punch!, Water Heaters November 30, 2011 Sonia


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By Matt Weber

 

Tankless water heaters have carved a healthy niche in the residential market thanks to their energy-efficiency and convenient on-demand hot water supply. Rheem now takes tankless technology a step further with the introduction of the company’s Prestige Series Condensing Tankless Gas Water Heaters.

The condensing technology of the new models enables them to be the most efficient home water-heating solutions available. A conventional tank-style water heater stores 40 to 50 gallons of hot water, and heats the water 24/7 whether you use it or not. The new generation tankless technology only heats water when you need it. When the faucet is opened, water flows through the heater, which warms it to the temperature you’ve digitally set. When the faucet is closed, the unit goes to standby mode. In addition to this on-demand performance, the Prestige Condensing Tankless Series features a new stainless steel condensing heat exchanger that achieves a .94 energy factor (94 percent thermal efficiency). The Prestige series also offers an industry best 0.26 GPM minimum flow rate and 0.40 GPM minimum activation flow rate, providing more fixture options, especially low-flow faucets and shower heads.

Another advantage is the small size of the heaters. A Rheem Prestige unit is significantly smaller than a conventional water heater. Sophisticated technology has reduced the size and increased the features, so it fits in more places and with less visibility.

The EHT staff replaced an old tank style unit with one of Rheem’s new Prestige condensing units, and the performance was vastly improved.

The digital display makes it simple to set the water temperature. Because the water is heated only when it is needed, the outgoing water temperature remains constant.

The digital display makes it simple to set the water temperature. Because the water is heated only when it is needed, the outgoing water temperature remains constant.

“The heated water is instantaneous,” says homeowner, Tom Wilson, of the new Prestige model. “It’s also easy to adjust the temperature with the remote-control thermostat.” The instant hot water delivery is continuous, supplying enough for three-bathroom homes. The units provide enough hot water for loads of laundry, washing dishes, bathing the kids and still enjoying a warm shower. Luxury bathrooms will also see a significant benefit, as the condensing tankless units provide oversize tubs with large volumes of low-cost hot water.

The vent exhaust and air-intake must be vented outside, separately from all other appliances.

The vent exhaust and air-intake must be vented outside, separately from all other appliances.

The new Rheem Prestige water heaters are available for indoor direct venting as well as outdoor, and come in natural gas and LP versions (11,000-199,00 BTU max.). One thing to evaluate when planning an installation of the new condensing units is the number of restrictions on the vent placement. The vent exhaust and air-intake must be vented outside, separately from all other appliances (and not through a chimney). The two-pipe direct |vent system is designed for PVC pipe, but Rheem specifies PVC Schedule 40 (ASTM D-1785) for the exhaust vent. However, most box stores in our area (Lowes, Home Depot) are only stocking the Cell Core 3”+  Schedule 40 PVC, which does not have an ASTM D-1785 rating. Additionally, both the tankless unit and the air-intake require condensation drains, which pose another consideration when determining installation location. Be sure to address these issues with your professional installer.

Both the tankless unit and the air-intake require condensation drains.

Both the tankless unit and the air-intake require condensation drains.

Venting requirements aside, the name of the game for tankless water heaters is energy efficiency, and the new Prestige units deliver it in spades. Rheem also backs the new models with a 12-year limited warranty on the heat exchanger, 5-year on parts and a year on labor. For more information on water heater technology, visit www.rheem.com.