GSW WATER HEATERS ATM-199M-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).
If you are checking this unit for a larger household with overlapping showers and laundry, it 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 the class median of 182 therms.
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
- 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
- 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 figure of 178 therms 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, of 0.95 with the DOE test's daily hot-water draw for the high draw pattern. It applies to natural gas at that test draw only. Actual use in a home depends on how much hot water the household draws, and this page holds no measured household data. The registry values were retrieved from DOE CCD on 2026-09-19. The calculation is set out in how the annual cost is calculated.
Among the 397 models registered as a gas tankless unit at the high draw pattern, this model has the 45th lowest energy use. That puts it in the lowest quarter of its class. The gap to the class median of 182 therms is 4 therms a year at the test draw. The unit suits a larger household, or one where showers and laundry overlap, and a reader who wants to compare energy use at that draw. Its maximum flow rate in gallons per minute is 6. The registry data does not show whether that flow meets a particular home's simultaneous demand, so this page does not assess it. It does not suit a reader who needs a figure for a lighter draw pattern, because only the high one is shown. Other fuels, spaces and sizes are covered by the water heater selector.
The running cost is not stated in this text because it depends on the state average residential gas price where you live. The cost calculator applies the rate for your ZIP to 178 therms at the high draw pattern. The same rate applied to the 4 therms gap from the class median of 182 therms shows what the difference is worth at your price. A cost figure is only as valid as the rate behind it. The modeled installed-cost range appears in its own block with its source and date; it is not a quote and is not repeated here. To compare GSW WATER HEATERS ATM-199M-N 1** with another unit of the same class, you can find a same-class replacement by model number.
DOE CCD · 2026-09-19