A.O. Smith 305 User Manual
INNOVATION ON DEMAND
A. O. Smith’s complete line of tankless gas water heaters
A Variety of Sleek, Compact Indoor Models To Choose From
305 and 505 Models
All Models Available
In Both Natural Gas
And Propane Designs
305 and 505
Height - Unit
Height - with brackets
Hot Water Outlet - from wall*
Hot Water Outlet - from center
Cold Water Inlet - from wall*
Cold Water Inlet - from center
Gas Connection - from wall*
Gas Connection - from center
From base to gas connection
From base to cold connection
From base to hot connection
*This is the minimum dimension from the wall. The wall bracket is adjustable to allow an additional 1.57 inches (40mm).
A. O. Smith
Residential and Commercial Product Features:
■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
■Interior sealed combustion
(does not use interior combustion air)
Outlet Flow Data
■ Models available that meet requirements of ASME Boiler and Pressure Vessel Code
■Up to 84% thermal efficiency, providing significant energy cost savings
Minimum Gas Consumption Btu/h
Maximum Gas Consumption Btu/h
199,000 Natural Gas
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)
7.1 GPM (26.9 L/min)
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)
50 lb (23 kg)
55 lb (25 kg)
Minimum Gas Supply Pressure
5.0 inch W.C.
8.0 inch W.C.
Maximum Gas Supply Pressure
10.5 inch W.C.
13.5 inch W.C.
Type of Appliance
Direct Vent, Temperature controlled continuous flow gas hot water system.
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.
Gas Supply: 3/4˝ MNPT, Cold Water Inlet: 3/4˝ MNPT, Hot Water Outlet: 3/4˝
Direct Electronic Ignition
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
Maximum Water Supply Pressure
Remote Control Cable
* 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.
500 Tennessee Waltz Parkway • Ashland City, TN 37015• www.hotwater.com
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