RELIANCE WATER HEATERS TK-510U-E 2**
0.81 UEF DOE CCD · 2026-09-19Grade G: where this UEF sits among the 397 models in its class, lowest (G) to highest (A). A position, not an official label. How the grade is set
A gas tankless unit, high draw pattern (a larger household, or one where showers and laundry overlap).
If you are checking the RELIANCE WATER HEATERS TK-510U-E 2** against the registry, here is its figure. At the high draw pattern, the standard daily hot-water usage DOE tests against, it uses 209 therms of natural gas a year. That is 27 therms above the 182 therms median for the 397 gas tankless units registered at that pattern.
Energy use per year
209 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 182 therms for the 397 models registered in the same heater type and draw pattern; it ranks 323 of 397, lowest energy first.
Solid line: this model (209 therms). Dashed line: the class median.
Min 173 therms Median 182 therms Max 209 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 high draw pattern.
- Draw Pattern the standard daily usage profile DOE tests the unit against
- High DOE CCD · 2026-09-19
- Maximum Gallons Per Minute how many gallons a minute it can heat while running continuously
- 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
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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
The 209 therms figure is computed by this site, not published by the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, with the DOE test's daily hot-water draw for the high pattern. This unit's UEF is 0.81, and the source is the DOE CCD, retrieved 2026-09-19. The figure holds only at that test draw. A household drawing more or less hot water will use a different amount of gas, and how much different is not available from this data. The method behind the annual energy and cost figures sets out each step.
The high draw pattern describes a larger household, or one where showers and laundry overlap. Within that class, this model ranks 323rd for lowest energy use out of 397. That places it in the highest quarter of its class for energy use. Its maximum flow rate in gallons per minute is 5, as registered. For a home that matches the high pattern, the 209 therms figure applies as stated. For a smaller household with a lower daily draw, it does not apply, and this page has no figure for other patterns. To compare units by a different fuel, space or size, the water heater selector by fuel, space and size filters the registry.
No running cost appears in this text, because it depends on your state's average residential gas price. The page computes it from your ZIP by applying that price to the 209 therms figure. The 27 therms gap to the 182 therms class median carries into the cost the same way, so its size depends on your rate. The cost calculator for your own ZIP shows that result. The installed-cost range sits in its own block on this page, with its source and date. It is a modeled range, not a quote. To check other models in the same class by model number, use the replacement finder for the same class.
DOE CCD · 2026-09-19