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TANKLESS HIGH EFFICIENCY
®
CONDENSING MODELS
Residential/Commercial Gas
Tankless Water Heaters
ATI and
Ultra-Low NOx Gas Tankless Water Heaters with Condensing
Technology featuring an unprecedented 0.95 Energy Factor which
lowers operating costs and is environmentally friendly
FEATURES
CONTINUOUS MAXIMUM FLOW
RATES UP TO 10.0 GPM
ENERGY STAR
®
QUALIFIED
AVAILABLE IN NATURAL GAS OR
PROPANE (LP)
ATI 540H & AT0 540H CAN BE USED
IN BOTH RESIDENTIAL AND
COMMERCIAL APPLICATIONS
INDOOR MODEL - INCLUDES
INTEGRATED TEMPERATURE
CONTROLS AND ADVANCED
DIAGNOSTICS TO SIMPLIFY
TROUBLESHOOTING
OUTDOOR MODEL - INCLUDES A
WALL MOUNT TEMPERATURE
REMOTE CONTROLLER AND
ADVANCED DIAGNOSTICS TO
SIMPLIFY TROUBLESHOOTING
FACTORY-INSTALLED POWER CORD
INCLUDED FOR INDOOR MODELS
DURABLE HEAT EXCHANGER
■ Primary Heat Exchanger is constructed of
HRS35, a Commercial-Grade Copper that is
more resilient to erosion. HRS35 is 25x
better at heat transfer than stainless steel
thus stabilizing outgoing water
temperatures quicker
■ Secondary Heat Exchanger is made of Type
316L Stainless Steel to protect against
corrosion
EASY-LINK UP TO 4 UNITS
(540H MODELS ONLY)
■ With no additional parts or accessories
needed
MULTI-LINK UP TO 20 UNITS
(540H MODELS ONLY)
COMMON VENT UP TO 8 UNITS
COMPLIES WITH LEAD FREE
STANDARDS
SAFETY FEATURES:
■ Air-Fuel Ratio (AFR) Sensor
■ Exhaust & Water Temperature Safety
Control
■ Overheat Cut-Off Fuse
INTERNAL FREEZE PROTECTION
SYSTEM
POWER DIRECT VENT DESIGN
■ Exhaust, 3" PVC Venting up to 70 Feet or
4" PVC Venting up to 100 Feet
■ Provides flexible venting with PVC, CPVC,
or ABS Pipe for Intake and Exhaust (solid
core only). Canadian Installations Require
ULCS636 Listed PVC or CPVC Pipe for
Venting.
■ Category IV Stainless Steel venting can
also be used
ACCESSORIES
■ Pipe Cover
■ Neutralizer Kit
■ Isolation Valve Kits
■ Concentric Termination
PRODUCT PRESERVERS
®
ANTI-SCALE SYSTEM
WARRANTY
■ 15-year limited warranty on heat
exchanger in residential applications
■ 10-year limited warranty on heat
exchanger in commercial applications
■ 5-year limited warranty on all parts
ATO240-540H
INDOOR MODELS
OUTDOOR MODELS
540 model
only
ANSI Z21.10.3 CSA 4.3
A. O. Smith Corporation • 500 Tennessee Waltz Parkway • Ashland City, TN 37015 • 800-527-1953 Toll-free USA Page 1 of 6
www.hotwater.com Revised February 2014 AOSRG46835
Page 2
Residential/Commercial Gas
Tankless Water Heaters
TANKLESS HIGH EFFICIENCY CONDENSING MODELS
MODEL
NUMBER
FUEL
TYPE
GAS CONSUMPTION
INPUT
MINIMUM
BTU/H
MAXIMUM
BTU/H
INLET GAS
PRESSURE
MINIMUM
W.C.
MAXIMUM
W.C.
ENERGY
FACTOR
MAX
GPM*
HOT/COLD
AND
GAS CONN.
DIMENSIONS IN INCHES
A
HEIGHTBWIDTHCDEPTH
INDOOR
ATI-240H-N Natural 15,000 160,000 5.0 10.5 0.95 6.6 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATI-240H-P Propane 13,000 160,000 8.0 14.0 0.95 6.6 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATI-340H-N Natural 15,000 180,000 5.0 10.5 0.95 8.0 3/4"NPT 23-5/8 17-3/4 11-1/4 58
ATI-340H-P Propane 13,000 180,000 8.0 14.0 0.95 8.0 3/4"NPT 23-5/8 17-3/4 11-1/4 58
ATI-540H-N Natural 15,000 199,000 5.0 10.5 0.95 10.0 3/4"NPT 23-5/8 17-3/4 11-1/4 59
ATI-540H-P Propane 13,000 199,000 8.0 14.0 0.95 10.0 3/4"NPT 23-5/8 17-3/4 11-1/4 59
OUTDOOR
ATO-240H-N Natural 15,000 160,000 5.0 10.5 0.95 6.6 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATO-240H-P Propane 13,000 160,000 8.0 14.0 0.95 6.6 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATO-340H-N Natural 15,000 180,000 5.0 10.5 0.95 8.0 3/4"NPT 23-5/8 17-3/4 11-1/4 58
ATO-340H-P Propane 13,000 180,000 8.0 14.0 0.95 8.0 3/4"NPT 23-5/8 17-3/4 11-1/4 58
ATO-540H-N Natural 15,000 199,000 5.0 10.5 0.95 10.0 3/4"NPT 23-5/8 17-3/4 11-1/4 59
ATO-540H-P Propane 13,000 199,000 8.0 14.0 0.95 10.0 3/4"NPT 23-5/8 17-3/4 11-1/4 59
All dimensions are in inches.
15-150 psi Water Pressure. 40 psi or above is recommended for maximum flow.
*Current numbers based on factory testing; 0.5 GPM for activation; 0.4 GPM required for continuous fire after initial ignition.
Indoor models are certified from sea level to 10,100 ft. elevations.
In accordance with ANSI Z21.10.3, CO emission does not exceed 400 PPM for normal input.
The manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligation.
UNIT
WEIGHT
(LBS)
For Technical Information call 1-877-737-2840. A. O. Smith Corporation reserves the right to make product changes or improvements without prior notice.
Revised February 2014
Page 2 of 6
AOSRG46835
Page 3
7-7/8" (199 mm)
GAS 5-1/8" (131 mm)
COLD 6-3/4" (172 mm)
HOT 5-1/2" (140 mm)
7-1/2" (189 mm)
GAS 5-7/8" (147 mm)
Condensate drain port
COLD 5/8" (17 mm)
HOT 4-3/4" (120 mm)
17-5/8" (448 mm)
6-1/4" (159 mm)
5-3/4" (147 mm)
120 VAC 3" (77 mm)
120 VAC 6-7/8" (174 mm)
∅
Drain port
Female
10-3/4" (272mm)
22-1/2" (570 mm)
Condensate drain port
4" (102 mm)
2-5/8" (68 mm)
Exhaust
Intake
Female
∅
7-7/8" (199 mm)
7-1/2" (189 mm)
7" (180 mm)
4" (101 mm)
17-3/4" (450 mm)
HOT 4-3/4" (120 mm)
6-3/4" (170 mm)
COLD 5/8" (17 mm)
GAS 5-3/4" (147 mm)
Condensate drain port
23-5/8" (600 mm)
2-5/8" (65 mm)
5-3/4" (147 mm)
11-1/4" (285 mm)
1/2 (13 mm)
GAS 5-1/8" (131 mm)
HOT 5-1/2" (140 mm)
COLD 6-3/4" (172 mm)
Condensate drain port
6-1/4" (159mm)
4" (102 mm)
24-7/8" (631 mm)
120 VAC 3" (77 mm)
Drain port 6" (152 mm)
120 VAC 6-7/8" (174 mm)
Residential/Commercial Gas
Tankless Water Heaters
INDOOR MODEL
For Technical Information call 1-877-737-2840. A. O. Smith Corporation reserves the right to make product changes or improvements without prior notice.
Revised February 2014
Page 3 of 6
AOSRG46835
Page 4
17-5/8" (448 mm)
6-1/4" (159 mm)
COLD 5/8" (17 mm)
120 VAC 3" (77 mm)
HOT 5-1/2" (140 mm)
HOT 4-3/4" (120 mm)
7-1/2" (189 mm)
Condensate drain port
GAS 5-1/8" (131 mm)
COLD 6-3/4" (172 mm)
7-7/8" (199 mm)
Drain port
7-1/2" (189 mm)
10-3/4" (272 mm)
22-1/2" (570 mm)
120 VAC
Condensate drain port
7-7/8" (199 mm)
Condensate drain port
11" (281 mm)
1/2" (13 mm)
120 VAC 3" (77 mm)
GAS (131 mm)
HOT (140 mm)
COLD 6-3/4" (172 mm)
Condensate drain port
COLD 5/8" (17 mm)
GAS 5-3/4" (147 mm)
HOT 4-3/4" (120 mm)
6-3/4" (170 mm)
1-1/2" (37 mm)
11-1/4" (285 mm)
120 VAC 6-1/4" (159 mm)
17-3/4" (450 mm)
7" (180 mm)
23-5/8" (600 mm)
24-7/8" (631 mm)
3-5/8" (92 mm)
4-1/2" (114 mm)
Drain port 6" (152 mm)
Residential/Commercial Gas
Tankless Water Heaters
OUTDOOR MODEL
Revised February 2014
For Technical Information call 1-877-737-2840. A. O. Smith Corporation reserves the right to make product changes or improvements without prior notice.
Page 4 of 6
AOSRG46835
Page 5
Residential/Commercial Gas
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11. 0
020406080100 120 140
Flow Rate (GPM)
Te mperature Rise (˚F)
Set temperature 125˚F (52˚C) or lower
Set temperature 130˚F (55˚C) or
higher
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11. 0
020406080100
Flow Rate (GPM)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11. 0
0 20 40 60 80 100
Flow Rate (GPM)
Tankless Water Heaters
FLOW RATE vs TEMPERATURE RISE
240H
340H
Flow Rate vs. Temperature Rise Flow Rate vs. Temperature Rise
Temperature Rise (°F)
Temperature Rise (°F)
540H
Flow Rate vs. Temperature Rise
Revised February 2014
For Technical Information call 1-877-737-2840. A. O. Smith Corporation reserves the right to make product changes or improvements without prior notice.
Temperature Rise (°F)
Page 5 of 6
AOSRG46835
Page 6
Residential/Commercial Gas
0
20
40
60
80
100
120
0
5
10
15
20
25
30
35
40
45
50
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
Pressure Loss (psi)
Head (Feet)
0
20
40
60
80
100
120
0
5
10
15
20
25
30
35
40
45
50
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
Head (Feet)
Pressure Loss (psi)
0
20
40
60
80
100
120
0
5
10
15
20
25
30
35
40
45
50
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0
Head (Feet)
Pressure Loss (psi)
Flow rate (GPM)
Set tempe rature 125˚F ( 52˚C) or lower
Set tempe rature 130˚F ( 55˚C) or higher
S
Tankless Water Heaters
PRESSURE LOSS
240H
Pressure Loss
Flow Rate (GPM)
340H
Pressure Loss
Flow Rate (GPM)
540H
Pressure Loss
A. O. Smith Corporation • 500 Tennessee Waltz Parkway • Ashland City, TN 37015 • 800-527-1953 Toll-free USA Page 6 of 6
www.hotwater.com Revised February 2014 AOSRG46835
Water heater(s) shall be Model_________________ as manufactured by A. O. SmithWater Heaters, shall be a copper coil integral fin and tube construction with quick release brass or bronze waterways. Heater(s)
will be factory assembled and tested.
The heater shall be vented with 3” or 4” Schedule 40 PVC, CPVC, or ABS vent pipe, or stainless steel Category III vent pipe at a distance not to exceed 70’ (equivalent) for 3” vent or 100’ (equivalent) for 4” vent,
terminating vertically or horizontally as prescribed. Intake air pipe may be of such material as ABS, PVC, galvanized B-Vent, corrugated aluminum or stainless steel, or Category IV stainless steel not to exceed
70’ (equivalent) for 3” vent or 100’ (equivalent) for 4” vent.
The heater(s) shall be controlled by an onboard solid-state printed circuit board monitoring incoming and outgoing temperatures with factory installed thermistors, sensing and controlling flow rate to set point
temperature, controlling both air and gas mixture inputs to maintain thermal combustion efficiency. The heater(s) shall also consist of inline fusing, a spark ignition and sensor system, aluminized stainless steel
burners, an air-fuel ratio sensor, a hi-limit temperature switch, modulating and proportional gas valves, a freeze protection sensor with ceramic heating blocks, and an overheat cutoff fuse.
The water heater(s) shall be CSA listed, exceed the energy efficiency requirements of ASHRAE 90.1b-1992, and shall comply with SCAQMD Rule 1146.2 Ultra-Low NOx Standards.
For Technical Information call 1-877-737-2840. A. O. Smith Corporation reserves the right to make product changes or improvements without prior notice.
Flow Rate (GPM)
Specification
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