A.O. Smith Commercial BTH-400
A.O. Smith Commercial BTH-400
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A.O. Smith - 119 Gal. Storage - 544 Gal. First Hour Delivery - 95% Thermal Efficiency - Natural Gas Water Heater - Direct Vent



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Free Shipping & Lift Gate
*This product qualifies for Free Shipping anywhere in the contiguous US. Accessories may ship separately. Items over 100lbs shipped via semi-truck, be sure to select "Lift Gate" to lower the product to the ground curbside. Remote area surcharges may apply, see our full shipping policy for more details.
Only 4 In-Stock
Ships Friday, Apr 23rd
Shipping to60601
Shipping Details
  • Lift Gate Service Available - Free Lift Gate Learn More
*We currently CANNOT ship this product to Canada or any destination outside of the United States
$119 / Month
With our 132 months 9.99% APR*
132 fixed monthly payments required.
Available Add-Ons
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Lift Gate Service
All products weighing more than 100 lbs. ship via semi-truck. We recommend ordering the Lift Gate Service to safely lower the product to the curb. If you have a loading dock or forklift, you do NOT need a Lift Gate service. If you are a residential customer, you must have at least 2-4 able-bodied people present to unload the product. Learn More
A.O. Smith - 119 Gal. Storage - 544 Gal. First Hour Delivery - 95% Thermal Efficiency - Natural Gas Water Heater - Direct Vent
A.O. Smith - 119 Gal. Storage - 544 Gal. First Hour Delivery - 95% Thermal Efficiency - Natural Gas Water Heater - Direct Vent
Model: BTH-400
How-To Articles


    A.O. Smith has led the way in innovative hot water solutions for nearly 80 years. The Cyclone Mxi is a highly efficient commercial water heater that has a rated thermal efficiency of 95% due to the modulating burner. Built with reliable components, the Cyclone Mxi provides you with years of hot water with minimal service needed. With its 119 gallon tank and easy to read display, the BTH-400 is ready to fulfill all of your hot water needs.
  • Helical Coil Heat Exchanger
  • The Cyclone Mxi line features a spiral heat exchanger that is positioned in the center of the unit for uniform heat distribution. It also allows the combustion gases to stay in the tank longer, lengthening the heat cycle and providing higher efficiency.
  • PermaGlass® Ultra Coat™
  • The tank has been coated using an industry exclusive glassing process where the coating is applied as a liquid and then mechanically rotated to ensure an even coat that provides protection against corrosion.
  • Fully Modulating Combustion
  • Modulating the burner results in higher operating efficiencies and longer service life by adjusting the firing rate as the demand changes.
  • Powered Anodes
  • All Cyclone Mxi models come with a titanium powered anode. A Powered anode works in all water conditions and never need replacing. It eliminates the possibility of odors usually related to standard anodes.
  • User-Friendly Electronic Interface
  • The intelligent control system, with easy to navigate menu, provides precise temperature control and unit operating information.
  • Venting Versatility
  • The Cyclone MXI line can be vented vertically or through a side wall. They can also have separate venting for the intake and exhuast or by using a concentric venting assembly.
  • iComm™ Compatible
  • These heaters are compatible with the iCOMM™ module, allowing them to be monitored remotely.
California residents see
WARNING: This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm..
For more information go to: www.p65Warnings.ca.gov


General Information
Gas Water Heater
Product Line
Cyclone Mxi
Medium Learn More
Medium refers to the substance that carries heat through the heating system. Systems are either designed to use either Hot Water or Steam as a medium, and components are usually specific to one or the other.
Hot Water
Fuel Type Learn More
Fuel Type
To create heat, some form of fuel is required. Fuel Type specifies what the product uses as an input to create heat.
Natural Gas
Combustion Type Learn More
Combustion Type
Condensing appliances use leftover thermal energy from combustion gases to heat water in a secondary heat exchanger, resulting in higher efficiency and lower exhaust temperature.
Vent Type Learn More
Vent Type
Products that use combustion (burning) of fuel to create heat also create potentially dangerous gasses that need to be exhausted (AKA "Vented"). Depending on the product, venting can be done via a chimney, through a side wall, or use a second vent to provide fresh air to the appliance.
Direct Vent
Storage Type
Mount Type
Maximum Input Capacity Learn More
Maximum Input Capacity
The Maximum Input Capacity describes how quickly the appliance will use fuel when delivering it's maximum capacity. The units may change depending on the fuel being used.
399900 BTU
First Hour Delivery Learn More
First Hour Delivery
Sometimes called First Hour Rating, this is the number of gallons of hot water the heater can supply per hour when starting with a fully heated tank. The recovery of the water heater depends on your boiler's BTU and boiler output temperature.
544 Gallons
Continuous Recovery Rate
512 Gallons
Efficiency Type
Thermal Efficiency
95 %
Ultra Low NOx Emissions Learn More
Ultra Low NOx Emissions
NOx is a byproduct of the combustion process, and it's output is regulated in some jurisdictions. Many regulators mirror SCAQMD rules, which regulate air quality for some parts of Southern California. Ultra Low NOx appliances emit less than 10-14 ng/J (nanogram per Joule) of NOx. Learn More
Electrical Data
60 Hz
Recommended Breaker Size
15 Amps
Storage Volume
119 Gallons
Primary Vent Pipe Diameter
4 Inches
Gas Connection Size
1 1/2 Inches
Cold Water Inlet
1 1/2 Inches
Hot Water Outlet
1 1/2 Inches
Product Height
75 3/4 Inches
Product Width
33 1/8 Inches
Product Depth
33 1/8 Inches
Product Weight
855 Pounds
Shipping Weight
855 Pounds
Energy Star Listed
UL Listed
CSA Listed
AHRI Certified
Warranty Information
Parts Warranty Learn More
Parts Warranty
A warranty is a safeguard from defects in manufacturing and can vary in length and terms. To see the manufacturer's warranty statement, click on the Manuals tab. Learn More
1 Year
Vessel Warranty
3 Years


A.O. Smith Commercial BTH-400 Reviews & Ratings

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Expert Recommended Accessories Selected by Bob, our Expert
Required Accessories 9
These accessories are required to properly setup/install this product.
Optional Accessories 10

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A.O. Smith - 119 Gal. Storage - 544 Gal. First Hour Delivery - 95% Thermal Efficiency - Natural Gas Water Heater - Direct Vent
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