RELIANCE WATER HEATERS TK-510C-NI 1**
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 verifying the RELIANCE WATER HEATERS TK-510C-NI 1**, a gas tankless unit, it uses 209 therms of natural gas a year. That figure belongs to the high draw pattern, the standard daily hot-water usage DOE tests against. It sits 27 therms above its class median of 182 therms, ranking 323rd lowest of 397 models.
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
- 4.7 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 calculated the 209 therms figure; the registry does not publish it. The calculation starts from the registry's UEF, the ratio of hot water delivered to energy used, which is 0.81 for this model. This site applies that value to the DOE test's daily hot-water draw for the high draw pattern. The source is the DOE CCD, retrieved 2026-09-19. The figure holds at the federal test's draw, not at any particular home's usage. The registry data do not show this unit's actual gas use in a home. The page on how the annual energy and cost figures are calculated sets out each step of the conversion.
The high draw pattern stands for a larger household, or one where showers and laundry overlap. The 209 therms figure describes use under that pattern, so it is the relevant comparison for homes of that kind. The registry lists a maximum flow rate in gallons per minute of 4.7 for this unit. Whether that flow covers several fixtures running at once depends on their combined demand, which the registry does not record. The comparison class is the 397 models registered as a gas tankless unit at the high draw pattern. All of them are measured on the same federal test basis, so their figures can be compared directly.
For a reader checking for low gas use at this draw pattern, this unit sits in the highest quarter of its class for energy use. The page does not state what the 27 therms gap to the class median costs each year. That cost depends on your state's average residential gas price. The page works out the running cost from your ZIP. The cost calculator for your own ZIP uses the same calculation. To compare this unit with models closer to the median, find a same-class replacement by model number. The installed-cost range on this page is a modeled range, not a quote.
DOE CCD · 2026-09-19