GSW WATER HEATERS ATM-180M-N 1**
0.95 UEF DOE CCD · 2026-09-19Grade B: 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 this unit? The GSW WATER HEATERS ATM-180M-N 1** uses 178 therms of natural gas a year at the high draw pattern, the standard daily hot-water usage DOE tests against. That is 4 therms below its class median of 182 therms, in the lowest quarter for energy use.
Energy use per year
178 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 45 of 397, lowest energy first.
Solid line: this model (178 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
- 0.95 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
- 5.4 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
- 2025-05-15 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
$2,358–$3,405 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 GSW WATER HEATERS model on file
What this brand files, by heater type.
UEF 0.95 · Grade B Price it on your ZIP
The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.95 for this gas tankless unit. The figure of 178 therms is not a registry entry. This site computed it from that UEF and the daily hot-water draw in the DOE test for the high draw pattern, so it describes the test conditions and not a particular home. The source data is DOE CCD, retrieved 2026-09-19. Among the 397 models registered as a gas tankless unit at the high draw pattern, this one ranks 45th lowest in energy use. The method behind the annual figure is documented separately.
The high draw pattern stands for a larger household, or one where showers and laundry overlap. The figure of 178 therms applies only to that pattern. A household that draws more or less hot water than the test day will use a different amount, and this page has no value for other draw patterns. The registry also lists a maximum flow rate in gallons per minute of 5.4. The data does not say whether that flow covers several fixtures running together in a given home, so it is a rated limit and nothing more. The selector by fuel, space and size handles those constraints. Against the class median of 182 therms, the gap of 4 therms is the only comparison this page makes on energy use.
Running cost is not written in this text because it depends on the average residential gas price in the reader's state. The page calculates it from the reader's ZIP, applying that price to 178 therms of natural gas. Any other price gives a different result, and a figure typed here without a price would be an estimate. The cost calculator shows the result for your own rate. The modeled installed-cost range appears in its own block with its source and date. It is a range, not a quote, and it is not repeated here. To look for a same-class unit, search by model number starting from ATM-180M-N 1**.
DOE CCD · 2026-09-19