Ruud RTGH-S11I
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).
Checking the Ruud RTGH-S11I? This gas tankless unit uses 176 therms of natural gas a year at the high draw pattern, the standard daily hot-water usage DOE tests against. That is 6 therms below the 182 therms median for the 397 gas tankless models registered at that 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
- 5.8 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
- 2022-08-01 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
-
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.
-
Find a water heater that fits
Three questions — fuel, hot water need, install space — narrow every model on file to the ones that fit.
-
What a water heater costs to run
Prices a unit's efficiency against your own utility's filed tariff for your ZIP code.
-
How to size a tankless water heater by GPM
Answered from what models in this size actually file.
-
Water heaters
Every model on file with the Department of Energy, by heater type.
-
All gas tankless water heaters
Gas-fired instantaneous units, sized by flow rate rather than tank gallons.
-
Every Ruud model on file
What this brand files, by heater type.
UEF 0.96 · Grade A Price it on your ZIP
The registry does not print the 176 therms figure. This site calculated it from the registry's UEF, the ratio of hot water delivered to energy used. This model's UEF is 0.96. The second input is the daily hot-water draw that the DOE test uses for the high pattern. The registry values come from the DOE CCD, retrieved 2026-09-19. Among the 397 gas tankless models registered at the high pattern, the RTGH-S11I ranks 12th lowest for energy use. At the test's draw, it sits 6 therms a year below the class median. The page on how this site calculates annual energy and cost explains each step.
The high draw pattern represents a larger household, or one where showers and laundry overlap. The 176 therms figure applies to a home with that usage. The registered maximum flow rate in gallons per minute for this unit is 5.8. This limit applies to hot water delivered at the same moment, not to the daily total. A household that needs more than 5.8 gallons per minute at once is beyond that registered limit. A household that uses less hot water than the test's daily draw will have a different annual figure. This data does not include that figure. To compare units in the same class, use the same-class replacement finder by model number or the water heater selector by fuel, space and size.
The running cost does not appear in this text because it depends on your state's average residential gas price. The page calculates it from your ZIP, using the 176 therms of natural gas at the high pattern. The cost value of the 6 therms gap below the 182 therms class median also depends on that price. To see the figure at your own rate, open the running-cost calculator for your own ZIP. The installed price range appears in a separate block, with its source and date. It is a modeled installed-cost range, not a quote, and it does not change the energy figures above.
DOE CCD · 2026-09-19