What is Energy Star Rating and Why It Matters to Tankless Water Heater Buyers

Many of us walk through the big box stores and hear this: “Well, according to the Energy Star rating, this unit will cost you nothing to run all year. In fact it is so good it will pay you money to use it.” Well, maybe I am over stating a bit, but its important to understand what everyone means when they start talking about Energy Star. Energy Star Ratings are a very important guide to helping you make purchase of anything from a freeze to a Tankless Water Heater.

This page of the Tankless Water Heater Guide is here to help you understand more about Energy Star. As always, feedback is important, so please join the discussion at the end of the page.

Energy Star is a federal program with the goal of helping homeowners choose products for their homes that use less energy. The results will be lower energy use and utility bills and a cleaner environment. Tankless water heaters are just one of dozens of home products such as building materials, appliances and heating and cooling components that are included in the Energy Star program.

Energy Star: What It Means

The Department of Energy and the Environmental Protection Agency work together to determine Energy Star requirements for each product. While the percentage varies based on the type of product it is, in general, to qualify as an Energy Star qualified product, it will most likely be in the top 25%-33% for efficiency for the type of product it is.

The Energy Star seal (Pictured Above) ensures consumers that they are choosing windows, doors, clothes washers, gas furnaces, heat pumps or yes, tankless water heaters that use significantly less energy than the average.

Energy Star and Tankless Water Heaters

Five criteria are considered when evaluating tankless water heaters: Fuel, size, efficiency, GPM flow rate and warranty. Only gas heaters are considered for Energy Star qualifications. Electric tankless water heaters do not qualify since electricity is not very efficient compared with gas. This is because fossil fuels are burned to create the electricity and then the electricity heats water. Directly using natural gas or liquid propane produces much higher efficiency.

Secondly, the tankless water heater must have a burner that ranges in capacity from 50,000 BTU to 200,000 BTU. That means that only whole-house tankless water heaters can qualify as Energy Star rated. For example, the Noritz NRC1111 has 2 burners that produce, total, 199,000 BTUs per hour. Noritz makes several smaller units that fit the criterion too, such as the Noritz NRC98 and the Noritz NRC83.

The Bosch Therm C 1210 ES, on the other hand, has a 225,000 BTU burner and it is very efficient, but just a bit too big. Models this size are excellent, however, when large quantities of hot water are required. Bosch does make smaller whole-house models that qualify.

The third criterion is Energy Factor which is a measure of energy efficiency. To be an Energy Star tankless water heater, the unit needs to have an Energy Factor (EF) of at least 0.82. This means roughly that 82% of the heat created must go directly to heating water with only 18% or less wasted in the exhaust gas. The  The Noritz NRC1111 has a .92 Energy Factor and the Navien CR/CC Series water heaters have energy factors as high as .98.

To achieve energy factors this high, many of these units use condensing technology. In brief, this means that they use the exhaust gases to preheat water coming into the heater to maximize the use of the heat created.

Fourthly, these water heaters need to be able to produce at least 2.5 gallons per minute (GPM) of hot water with a 77-degree F rise. Many Energy Star models can produce 4 GPM or more with at least a 77F rise. That’s not a problem for large-capacity tankless water heaters.

Finally, to qualify as an Energy Star tankless water heater, the unit must have a warranty of 10 years or more on the heat exchanger and 5 years or more on parts. For example, most Noritz tankless water heaters and many Rinnai water heaters are backed by a 12-year heat exchanger and a 5-year parts warranty. Bosch offers some of the best warranties: 15-year heat exchanger and 5-year parts warranties. EnergyStar.Gov states that most tankless heaters have significantly better longevity than storage water heaters.

Choosing the Right Tankless Water Heater

See reviews for most of the models mentioned here as well as many more. Consider how much capacity you need and how much extra you’re willing to spend to get a more efficient water heater. Remember, the more efficient the model is, the less energy you will uses, the less money you’ll spend on energy costs and the more ecofriendly your water heating will be.

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