A.O. Smith 305 User manual

A. O.SMITH’S
INNOVATION ON DEMAND
A. O. Smith’s complete line of tankless gas water heaters
A Variety of Sleek, Compact Indoor Models To Choose From
All Models Available
In Both Natural Gas
And Propane Designs
305 and 505 705
Dimension Description inches (mm) inches (mm)
A Width 14 (355.6) 18.5 (470)
B Depth 9.6 (244.5) 9.3 (230.5)
C Height - Unit 22.9 (582) 23.6 (600)
D Height - with brackets 25.5 (648.2) 25.2 (640)
E Hot Water Outlet - from wall* 3.6 (91) 4.5 (115)
F Hot Water Outlet - from center 4.3 (110) 2.4 (61)
G Cold Water Inlet - from wall* 2.8 (70) 3.9 (99)
H Cold Water Inlet - from center 1.1 (27) 2.0 (52)
I Gas Connection - from wall* 4.3 (109) 2.4 (61.2)
J Gas Connection - from center 3.5 (89) 4.3 (110)
From base to gas connection 1.6 (40) 1.6 (40)
K From base to cold connection 2.0 (50) 2.0 (50)
From base to hot connection 1.6 (41) 1.6 (41)
* This is the minimum dimension from the wall. The wall bracket is adjustable to allow an additional
1.57 inches (40mm).
Model Dimensions
ATI-305-N (Natural Gas), ATI-305-P (Propane)
ATI-505-N (Natural Gas), ATI-505-P (Propane)
305 and 505 Models
ATI-705-N (Natural Gas), ATI-705-P (Propane)
ATI-705A-N (Natural Gas), ATI-705A-P (Propane) Commercial
705 Model

A. O. Smith On-Demand Gas Water Heaters
AMGSS00207 ©2007 A. O. Smith Corporation A. O. Smith reserves the right to make product changes or improvements at any time without notice. Printed in U.S.A
500 Tennessee Waltz Parkway •Ashland City, TN 37015 •www.hotwater.com
Residential and Commercial Product Features:
Innovative Technology
■A variety of indoor installation options
■Continuous hot water on demand (up to 9.8 GPM)
■Whole house water heating solution
■Direct electronic ignition – no pilot light
■On-board diagnostics and safety monitoring
■Interior sealed combustion
(does not use interior combustion air)
Excellent Performance
■12-year limited warranty on heat
exchanger, 5-year warranty on all parts
■Models available that meet requirements
of ASME Boiler and Pressure Vessel Code
Energy Efficiency
■Up to 84% thermal efficiency, providing
significant energy cost savings
Model 305 505 705
Minimum Gas Consumption Btu/h 15,000 19,000
Maximum Gas Consumption Btu/h 199,000 Natural Gas 237,000
190,000 Propane Gas
Hot water capacity (Min - Max)* 0.6 - 5.3 GPM 0.6 - 8.5 GPM 0.6 - 9.8 GPM
(2.3 - 20.1 L/min) (2.3 - 32.0 L/min) (2.3 - 37 L/min)
Hot water capacity (45°F rise) 7.4 GPM (28.0 L/min)
5.3 GPM Natural Gas 8.8 GPM
(20.1 L/min) 7.1 GPM (26.9 L/min) (33.5 L/min)
Propane Gas
Default Temperature Setting (no controller) 120º F (49º C)
Remote Controller Default Temperature Setting 104º F (40º C)
Maximum Temp Setting (Commercial**) 160º F (71º C) 185º F (85º C)
Maximum Temp Setting (Residential) 140º F (60º C)
Minimum Temperature Setting 98º F (37º C)
Weight 50 lb (23 kg) 55 lb (25 kg)
Efficiency Rating 84%
Noise level 49 dB
Electrical Consumption Normal 79 W 99 W
Standby 2.8 W 2 W
Anti-frost Protection 100 W 116 W
By-Pass Control Fixed Electronic
Minimum Gas Supply Pressure Natural Gas 5.0 inch W.C.
Propane 8.0 inch W.C.
Maximum Gas Supply Pressure Natural Gas 10.5 inch W.C.
Propane 13.5 inch W.C.
Type of Appliance Direct Vent, Temperature controlled continuous flow gas hot water system.
Operation With or without remote controls, mounted in kitchen, bathroom, etc.
Approved Gas Type Natural Gas or Propane - Ensure unit matches gas type it's being installed on.
Connections Gas Supply: 3/4˝ MNPT, Cold Water Inlet: 3/4˝ MNPT, Hot Water Outlet: 3/4˝
Ignition System Direct Electronic Ignition
Electric Connections Appliance: AC 120 Volts, 60Hz. Remote Control: DC 12 Volts (Digital)
Water Temperature Control Simulation Feedforward and Feedback.
Water Supply Pressure Minimum Water Pressure: 20 PSI (Recommended 30-80 PSI for maximum
Maximum Water Supply Pressure 150 PSI
Remote Control Cable Non-Polarized Two Core Cable (Minimum 22 AWG)
* Minimum flow may vary slightly depending on the temperature setting and the inlet water temperature.
** for commercial and hydronic applications requiring higher temperatures
Specifications are subject to change without prior notice.
The maximum inlet gas pressure must not exceed the value specified by the manufacturer. The minimum value listed is for the purpose of input adjustment.
Model Specifications
Outlet Flow Data