Whole-House Tankless Water Heater Efficiency Ratings

July 26, 2022

A growing number of Denver-Boulder area homeowners are making the switch to whole-house tankless gas water heaters, forgoing traditional tank-type heaters. While both options continue to present their particular benefits, tankless water heaters are often selected because of their efficiency and gas savings, and their compact physical footprint. In addition, these types of water heaters typically have a longer design life than standard tanks.

If you’re considering switching over to the tankless option, this blog article presents helpful information about their efficiency ratings, and how they compare to other popular water heaters.

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What Is a UEF Rating?

In short, the UEF, or Uniform Energy Factor, measures the efficiency of a water heater. Without getting too deep into the weeds on the math and how the UEF is calculated, the important thing to know is the higher the number, presented in a decimal form, the more efficient the water heater is. Most water heaters, both tank and tankless, have an efficiency rating ranging between 0.55 and 0.93 UEF, and there are exceptions to this rule of thumb (fans of “green” products such as heat pump water heaters). When comparing apple-to-apples, an important caveat, the higher the UEF the lower the projected operating costs.

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Regarding those above mentioned “apples,” much as we’d love to provide operating cost comparisons and performance rules of thumb here to help our readers decide what kind of water heater is best for them, we just don’t feel that’s wise in this limited space. We recommend deferring that particular conversation until an experienced plumbing and heating pro has a chance to look closer at your specific circumstances. As you’ll see – and some may recall from a recent blog article by our team – the UEF rating is just one of several important considerations when purchasing a new water heater.

Comparing UEF Ratings With Tankless Water Heaters

The numbers presented here are based on the Rinnai and Navien tankless gas water heater lines, and Bradford White and Rheem brand tank type water heaters, all of which our team currently installs.

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Tankless Water Heater Efficiency Ratings

Gas-fired tankless water heaters have a high end efficiency range of around 0.85 UEF to 0.96 UEF. These ratings are normally found on condensing design equipment, the most advanced and efficient types of tankless heaters. On the lower end, non-condensing tankless options generally carry ratings in the 0.80-0.82 UEF range, which is still much higher than traditional gas-fired tanks. These numbers cover both natural gas and propane-fired units, as well as heaters that are designed to be installed indoors or outdoors.

Rinnai Tankless Water Heaters

Traditional Gas Water Heater UEF Ratings

In comparison, gas-fired tank water heaters have efficiencies ranging from approximately 0.54 UEF to 0.72 UEF. Models with fan assisted or direct vent exhaust designs (sidewall venting units) are in the higher end of this group, while the traditional gravity-vent tank type heaters that are found in many Denver-Boulder homes are in the lower end of this efficiency range. High recovery units are also on the lower end.

Electric Tank Water Heater Efficiencies

Another option that’s not as popular as many years ago are standard, electric tank water heaters, which typically carry efficiency ratings ranging from 0.91 UEF to 0.93 UEF across the board. It is well worth noting that while the UEF ratings of these water heaters are relatively high, their recovery ratings and first-hour ratings are generally very low. This is due to the limitations of how those products use electricity to heat water.

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If judging solely by UEF ratings, electric tank water heaters might appear to be a great option at first glance, but as many homeowners may already understand, the UEF rating is just one of several important factors when choosing a new water heater. While the UEF is certainly an important number, it’s definitely not the end-all in the decision making process. Homeowners in the Denver-Boulder area regularly turn to our plumbing team at Save Home Heat for friendly, helpful advice in sorting out the alphabet soup associated with water heaters.

The Hybrid Electric/Heat Pump Water Heater ‘Green’ Option

Lastly, it’s also worth discussing hybrid electric heat pump water heaters. Talk about a mouthful! These electric-powered tank type heaters are still relatively new to the residential hot water scene, and continue to gain momentum with homeowners seeking to move away from reliance on fossil fuels to a highly electrically efficient product. The efficiency ratings of these heat pump-based water heaters currently ranges between an impressive 3.4 UEF and 4.0 UEF. We’re guessing it may not be very long before new construction code in municipalities around the Denver-Boulder area starts requiring similar equipment. Installing and servicing these products requires greater expertise than other tank type heaters.

Rheem Water Heater

Whole-House Tankless Water Heaters Don’t Waste Gas!

Whole-house gas tankless water heaters offer a desirable combination of high UEF efficiency ratings and high heating capacity, as well. When properly sized and professionally installed in the right application, these products can supply whole-house hot water needs more effectively than virtually all electric tank products and more efficiently than other gas-fired options. The primary component in modern tankless heaters that makes this possible is their self-adjusting, modulating gas valve that virtually eliminates wasted gas by supplying just the right amount of heat needed to achieve the desired water temperature.

Tankless Water Heater Expertise for Denver-Boulder Homeowners

Boulder-Denver homeowners contact our team at Save Home Heat Company frequently for expert assistance and professional recommendations on hot water solutions that are a good fit for their current needs and future plans. We’d be glad to discuss whole-house tankless water heaters with you in a highly informative, stress-free, friendly manner, along with any other hot water solutions that we feel make sense for you to consider. Please reach out to us for more information, or to schedule a free, no obligation install quote.

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