A. O. Smith T-H3J-OS-N (ATO-240H 1) is a gas tankless water heater from A. O. Smith rated 4.7 GPM at a 0.95 UEF — 178 therms/yr certified use, 160k BTU/h input.
Efficiency
Uniform Energy Factor (UEF)
0.95
Annual gas use (natural gas)
178 therms/yr
Annual propane use
194.53 gal/yr
General
Fuel
Natural Gas
Capacity
Max flow rate
4.7 GPM
Draw pattern
High
Minimum activation flow
1 GPM
Performance
Gas input rate
160 kBTU/h
Installation
Max current draw
5 A
Vent type
Power Vent
Vent size
0
Smart features
Smart / connected capable
No
Dimensions
Height
22 in
Width
18 in
Depth
11 in
Certification
ENERGY STAR certified
Yes
Real flow rate by climate
A tankless heater's usable flow depends on how far it must raise incoming water
temperature. Sustained hot-water flow of the A. O. Smith T-H3J-OS-N (ATO-240H 1) at common temperature
rises (a typical shower uses about 2 GPM of mixed water):
Temperature rise
Climate
Sustained flow
Simultaneous showers
45 °F
Warm climate (~75 °F groundwater)
4.7 GPM
2
55 °F
Mild climate (~65 °F groundwater)
4.7 GPM
2
70 °F
Cold climate (~50 °F groundwater)
4.3 GPM
2
77 °F
DOE test condition
3.9 GPM
1
Also sold as
The A. O. Smith T-H3J-OS-N (ATO-240H 1) is certified hardware that A. O. Smith and its partner brands
publish under 13 names. The same specifications apply to every
variant:
Is the A. O. Smith T-H3J-OS-N (ATO-240H 1) ENERGY STAR certified?
Yes, the A. O. Smith T-H3J-OS-N (ATO-240H 1) holds a current ENERGY STAR certification for water heating efficiency (UEF 0.95).
How much does the A. O. Smith T-H3J-OS-N (ATO-240H 1) cost to run per year?
About $258 per year at national average energy rates, based on its certified annual energy use under the DOE test draw pattern. Your rate and usage change this figure.
What venting does the A. O. Smith T-H3J-OS-N (ATO-240H 1) use?
The A. O. Smith T-H3J-OS-N (ATO-240H 1) uses Power Vent venting with 0 in vent connections. Matching the existing vent type is usually the cheapest replacement path.
Is the A. O. Smith T-H3J-OS-N (ATO-240H 1) a smart water heater?
No, the A. O. Smith T-H3J-OS-N (ATO-240H 1) is not connected-capable — it has no app connectivity or demand-response support.
