Ruud RTGH-S84I
0.96 UEF DOE CCD · 2026-09-19Grade A: 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 Ruud RTGH-S84I, this gas tankless unit uses 176 therms of natural gas a year. That figure applies to the high draw pattern, the standard daily hot-water usage DOE tests against. It sits 6 therms below the 182 therms median of the 397 gas tankless models registered at the high draw pattern.
Energy use per year
176 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 below the median of 182 therms for the 397 models registered in the same heater type and draw pattern; it ranks 12 of 397, lowest energy first.
Solid line: this model (176 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
- 0.96 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
- 4.6 gal/min DOE CCD · 2026-09-19
- On the market since (ENERGY STAR) the date the manufacturer told ENERGY STAR the model went on sale
- 2023-01-01 ENERGY STAR · 2026-09-19
- Connected / demand response (ENERGY STAR) whether the unit can take signals from your utility to shift when it heats, and by which standard (such as CTA-2045)
- No ENERGY STAR · 2026-09-19
What it costs to install
$2,405–$3,460 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 · 2026-09-24Does it fit your space?
Enter your own numbers below — this compares them to what ENERGY STAR publishes for this model, it does not tell you what to buy.
- Dimensions (ENERGY STAR)
- the unit's filed height, width, depth or tank diameter, in inches
- Input voltage and maximum current (ENERGY STAR)
- the circuit voltage the unit is certified on and the most current it draws
- Vent type and size (ENERGY STAR)
- how a gas unit is vented, the vent's diameter and the height of its vent connector
What 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 Ruud model on file
What this brand files, by heater type.
UEF 0.96 · Grade A Price it on your ZIP
This site calculated the 176 therms figure; the registry does not list it. It combines the registry's UEF, the ratio of hot water delivered to energy used, with the daily hot-water draw the DOE test sets for the high draw pattern. For this model the registered UEF is 0.96. Both inputs come from the DOE CCD, retrieved 2026-09-19. The figure holds only at that test draw. A home that uses more or less hot water in a day will burn more or less gas. Within its class, this model ranks 12th for lowest energy use among the 397 models. That places it in the lowest quarter of its class for energy use. The page on how the annual cost is calculated sets out each step behind the figure.
The high draw pattern represents a larger household, or one where showers and laundry overlap. The 176 therms figure describes that kind of use and no other. This unit's maximum flow rate in gallons per minute is 4.6, as registered. That rating caps how much hot water it delivers at one moment, separate from the daily total. For a home with lighter use, the test condition does not match, so the 176 therms figure does not describe that home. The gap to the class median, given above, also holds only at the high draw pattern. To compare units of other fuels or sizes, use the selector by fuel, space and size. To check another gas tankless model in the same class, find a same-class replacement by model number.
This text does not state the running cost. It depends on your state's average residential gas price, so the page computes it from your ZIP. That cost is based on the 176 therms of natural gas this model uses a year at the high draw pattern. The 6 therms difference from the class median is priced at the same rate as the rest of the figure. The installed-price block on this page shows a modeled installed-cost range with its own source and date; it is not a quote. To see a cost on your own rate, open the cost calculator on your own ZIP. Your home's actual yearly gas use is not available here, because the registry holds test values only.
DOE CCD · 2026-09-19