RELIANCE WATER HEATERS TK-110U-I 2**
0.81 UEF DOE CCD · 2026-09-19Grade G: where this UEF sits among the 80 models in its class, lowest (G) to highest (A). A position, not an official label. How the grade is set
A gas tankless unit, medium draw pattern (a typical three- or four-person household, about 55 gallons on a busy morning).
If you are checking the RELIANCE WATER HEATERS TK-110U-I 2**, this gas tankless unit uses 137 therms of natural gas a year. That figure applies at the medium draw pattern, the standard daily hot-water usage DOE tests against. It sits 2 therms above the class median of 135 therms. It ranks 52nd lowest in energy use of 80 models.
Energy use per year
137 therms a year
Computed by this site from the registry's UEF and the federal test's daily hot-water draw for this draw pattern. What it costs depends on the natural gas rate where you live.
That is above the median of 135 therms for the 80 models registered in the same heater type and draw pattern; it ranks 52 of 80, lowest energy first.
Solid line: this model (137 therms). Dashed line: the class median.
Min 114 therms Median 135 therms Max 137 therms
What it costs to run where you live
What the registry files
- UEF (Uniform Energy Factor) how much hot water you get for each unit of energy the heater uses
- 0.81 DOE CCD · 2026-09-19 Compared only with other models registered as a gas tankless unit at the medium draw pattern.
- Draw Pattern the standard daily usage profile DOE tests the unit against
- Medium DOE CCD · 2026-09-19
- Maximum Gallons Per Minute how many gallons a minute it can heat while running continuously
- 3.5 gal/min DOE CCD · 2026-09-19
What it costs to install
$1,698–$2,632 installed
Not a quote — a modeled range of what installers have charged for this class of unit; your price will vary with labor rates, access, and local code requirements.
Escalation indexes: equipment (BLS PPI) latest available: August 2026; labor (BLS ECI) latest available: April 2026 to June 2026.
NLR REMDB (BLS PPI/ECI escalated) · 2026-04-01Safety record
No CPSC recall names this model.
Checked against the CPSC recall database. CPSC does not publish a model-level match for this product category, so this list is curated by hand from the manufacturer's recall filings.
CPSC · 2026-09-24What these figures mean
How this compares
The closest models in the same class — same fuel, type and draw pattern.
Keep going
How every figure on this page is calculated
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Find what replaces your water heater
Enter the model number off your old unit and see what is on file today, with the yearly cost difference.
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Find a water heater that fits
Three questions — fuel, hot water need, install space — narrow every model on file to the ones that fit.
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What a water heater costs to run
Prices a unit's efficiency against your own utility's filed tariff for your ZIP code.
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How to size a tankless water heater by GPM
Answered from what models in this size actually file.
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Water heaters
Every model on file with the Department of Energy, by heater type.
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All gas tankless water heaters
Gas-fired instantaneous units, sized by flow rate rather than tank gallons.
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Every RELIANCE WATER HEATERS model on file
What this brand files, by heater type.
UEF 0.81 · Grade G Price it on your ZIP
This site calculates the 137 therms figure. The registry does not list it. The calculation uses the model's UEF, the ratio of hot water delivered to energy used, and the DOE test's daily hot-water draw for the medium pattern. The registry lists a UEF of 0.81 for this model. Our source is the DOE Compliance Certification Database (CCD), retrieved 2026-09-19. The calculation uses the test draw, so the figure describes the test condition. It is not a measured bill. A home that uses more hot water each day than the test assumes will use more gas than 137 therms. A home that uses less hot water will use less gas. The full steps are in how the annual energy and cost figures are calculated.
The TK-110U-I 2** is compared with the 80 models registered as a gas tankless unit at the medium draw pattern. Their median is 135 therms a year, and this model uses 2 therms more than that. It ranks 52nd lowest in energy use of the 80. Every model ranked ahead of it uses less gas at the same test draw. The registry also lists a maximum flow rate in gallons per minute of 3.5 for this model. The energy figure applies most closely to a household whose daily hot-water use is near the medium pattern. The registry does not report this model's energy use at other draw patterns, so no such figure is available. To look up other models in this class by number, use find a same-class replacement by model number.
This text does not state a running cost. The cost depends on the average residential natural gas price in the reader's state. The page calculates the yearly cost from 137 therms and the gas price for your ZIP code. No cost is estimated in this text. Enter your ZIP in the running cost calculator for your own ZIP to see that figure. The 2 therms gap to the class median depends on the same rate. A higher local gas price makes the cost of that gap larger, and a lower price makes it smaller. The installed price range is shown in its own block on this page, with its source and date. It is a modeled installed-cost range, not a quote.
DOE CCD · 2026-09-19