A.O. Smith ATI-510U-N, ATO-510U-N Technical Documents

Residential/Commercial Gas

Ultra-Low NOx Tankless Water Heaters

Fully modulating, gas fired, tankless water heater with sealed combustion and power
vented flue. Indoor and outdoor models available for residential applications.
Supplies hot water to domestic hot water systems (directly or indirectly) can be used
with water storage tanks, recirculation systems, hydronic heating systems, radiant
floor heating systems, and/or combined domestic & heating applications.

FEATURES

COMPLIES WITH ULTRA-LOW NOx REGULATIONS

MAXIMUM FLOW RATES UP TO 10.0 GPM

PRIMARY HEAT EXCHANGER

I Stronger than standard copper and more resilient against erosion

INDOOR AND OUTDOOR MODELS AVAILABLE

OUTDOOR MODELS INCLUDE REMOTE CONTROL AS A STANDARD FEATURE

INDOOR MODELS INCLUDE BOTH A REMOTE CONTROL AND POWER CORD AS
STANDARD FEATURES

®

ENERGY STAR

AVAILABLE IN NATURAL GAS

QUALIFIED

INDOOR MODELS

ATI-110U, ATI-310U,

ATI-510U

EASY-LINK UP TO 4 UNITS (510U MODELS ONLY)

I With no additional parts or accessories needed

MULTI-LINK UP TO 20 UNITS (510U MODELS ONLY)

COMPLIES WITH LEAD FREE STANDARDS

ATI-510U AND ATO-510U CAN BE USED IN BOTH RESIDENTIAL AND
COMMERCIAL APPLICATIONS

SAFETY FEATURES:

I Built-in Freeze Protection
I Manual Reset Hi Limit (Up to 194°F)
I Overheat Cutoff Fuse
I Inlet and Outlet Thermistors for Constant Temperature Monitoring
I Air Fuel Ratio Rod
I Flame Sensor

VENTING AND COMBUSTION

I 4” Category III Stainless Steel
I Vertical or Horizontal Installation
I 50’ Max Length, 5 Elbows max (90° elbows = 5’ equivalent length)
I Power Vent
I Electronic Ignition - No Pilot Light
I 3” Combustion Air Intake (with optional kit)

OPTIONAL ACCESSORIES

I Complete Line of Stainless Steel Venting
I Recess Box (outdoor)
I Pipe Cover
I Direct Vent Conversion Kit (indoor)
I Isolation Valve Kits
I Backflow Preventor
I Concentric Termination Kits

WARRANTY

I 12-year limited warranty on heat exchanger in residential applications
I 5-year limited warranty on heat exchanger in commercial applications
I 5-year limited warranty on all parts

OUTDOOR MODELS

ATO-110U, ATO-310U,

ATO-510U

®

(510U models only)

ANSI Z21.10.3

CSA 4.3

Page 1 of 4

AOSBG45100

Residential/Commercial Gas

Ultra-Low NOx Tankless Water Heaters

ULTRA-LOW NOx TANKLESS MODELS

GAS CONSUMPTION

INPUT

MODEL

NUMBER

ATI-110U-N Natural 15,000 140,000 0.82 5.0 10.5 6.6 20-1/2 13-4/5 8-1/2 120 0.54 4” O.D. 3.0” O.D. 3/4” NPT 37

ATO-110U-N Natural 15,000 140,000 0.82 5.0 10.5 6.6 20-1/2 13-4/5 8-1/2 120 0.54 4” O.D. 3.0” O.D. 3/4” NPT 37

ATI-310U-N Natural 15,000 190,000 0.82 5.0 10.5 8.0 20-1/2 13-4/5 8-1/2 120 0.83 4” O.D. 3.0” O.D. 3/4” NPT 37

ATO-310U-N Natural 15,000 190,000 0.82 5.0 10.5 8.0 20-1/2 13-4/5 8-1/2 120 0.83 4” O.D. 3.0” O.D. 3/4” NPT 37

ATI-510U-N Natural 15,000 199,000 0.82 5.0 10.5 10.0 20-1/2 13-4/5 8-1/2 120 0.86 4” O.D. 3.0” O.D. 3/4” NPT 39

ATO-510U-N Natural 15,000 199,000 0.82 5.0 10.5 10.0 20-1/2 13-4/5 8-1/2 120 0.86 4” O.D. 3.0” O.D. 3/4” NPT 39

All dimensions in inches.
15-150 psi water pressure. 40 psi or above recommended for maximum flow.
* Category III required
**Current numbers based on factory testing, 0.4 GPM required for continuous fire after initial ignition.
Pressure only relief valve required (Min. 200,000 BTUs. 150 PSI). Min 50 PSI or above recommended for maximum flow.
Complies with Ultra-Low NOx regulations (SCAQMD Rule 1146.2) effective January 1, 2012.
Freeze protection draws 1.1 AMP
Indoor models are certified from sea level to 8,000 ft. elevations.

FUEL
TYPE

MIN.

BTU/H

MAX.

BTU/H

ENERGY

FACTOR

(EF)

INLET GAS
PRESSURE

MIN.

W.C .

MAX.

W.C .

MAX

HEIGHT WIDTH DEPTH

GPM**

DIMENSIONS

IN INCHES

VOLT AMP FLUE*

INTAKE

(OPTIONAL)

HOT/COLD

GAS

CONN.

WEIGHT

INDOOR MODEL

3-5/8" (94 mm)

Front view

13-3/4" (350 mm)

10" (254 mm)

7" (180 mm)

∅4 (101 mm)

Side view

4-3/8" (113 mm)

UNIT

(LBS)

1-3/8" (36 mm)

2-1/4" (58 mm)

19-3/8" (493 mm)

20-1/4" (520mm)

1" (26 mm)
120 VAC 3" (75 mm)
GAS 5-1/4" (135 mm)

1-7/8" (47 mm)

HOT 4-5/8" (116 mm)

120 VAC 1-5/8" (40 mm)
COLD 1-5/8" (41 mm)
GAS 5" (127 mm)

CLEARANCES: Top 12”, Bottom 12”, Front 24”, Back 0.5”, Sides 2”

For Technical Information call 1-877-737-2840. A. O. Smith Corporation reserves the right to make product changes or improvements without prior notice.

COLD 6" (153 mm)
HOT 6" (153 mm)
9-1/2" (241 mm)

Page 2 of 4

www.hotwater.com AOSBG45100