Corderite Combustion Containment
Flammable Vapor Ignition Resistant Technology
Residential Gas Water Heaters

Committed to value and continuous product improvement
At A.O. Smith Water Products Company, we are committed to providing our customers with water that deliver Value.  Value comes from building products of consistently high quality that provide years of reliable service to homeowners; appliances that heat water efficiently, to save energy and money for the homeowner; water heaters with the features our customers have come to expect from a leader, features that make our products easier to install and easier to maintain. Finally, we remain committed to manufacturing water heaters that meet all applicable industry regulations and codes.
Anticipated C3 TechnologyT Gas Water Heaters Introduction Schedule:
PHASE 1: JULY 1, 2003
30-, 40- and 50-gallon atmospheric vent models with 14-inch to 18-inch internal tank diameters. Manufactured housing models and "combination" models equipped for water heating and space heating are excluded.
PHASE 2: JULY 1, 2004
30-, 40-and 50-gallon power-vented models with 14-inch to 18-inch internal tank diameters. Manufactured housing models and "combination" models are excluded.
PHASE 3: JULY 1, 2005
All other gas-fired models with inputs of 75,000 BTU or less.
A major design initiative
In keeping with our commitment to continuous product improvement, A.O. Smith's engineering group has developed an innovative new design for our gas residential water heaters. Our new C3 TechnologyT gas water heaters feature a new sealed combustion chamber and a new flame arrester component and are covered by four U.S. patents.
A.O. Smith C3 TechnologyT gas water heaters will meet new standards and testing protocols established by the American National Standards Institute (ANSI) that deal with the accidental or unintended ignition of flammable vapors, such as those emitted by gasoline. By July 1, 2005, the new ANSI Z21.10.1 standard will cover virtually all gas-fired residential water heaters manufactured in the United States with BTU inputs of 75,000 or less. A.O. Smith residential water heaters will meet the new ANSI standards in accordance with the schedule above.
How new A.O. Smith C3 TechnologyT gas water heaters work

Sealed combustion chamber with lint, dust and oil (LDO) screen
The only place where air for combustion may enter the patented, sealed combustion chamber is through a port in the water heater base. From there, combustion air flows one way-up through the flame arrester. The air inlet port is equipped with a removable LDO screen that helps prevent foreign matter from clogging the flame arrestor and possibly causing poor combustion and reduced efficiency.

Corderite flame arrestor
The flame arrestor is built into the water heater base and is made from Corderite, a low thermal conductive fireproof material. Incoming air flows through the flame arrestor, which distributes the air evenly to the gas burner. In the unlikely event that flammable vapors are introduced accidentally into the combustion chamber, the flame arrestor is designed so any flames burn off the top surface and cannot escape down through the flame arrestor.

Combustion chamber temperature sensor
Our new C3 TechnologyT gas water heaters will come equipped with a thermal cutoff (TOO) device that is integral with the thermocouple. Factory preset shutoff points range from 140 degrees C to 200 degrees C depending on the gallon capacity and input of the water heater, among other factors. The TCO device performs two functions:
. In the event of flammable vapor ignition inside the combustion chamber, it senses the corresponding increase in temperature and shuts off gas flow to the burner and pilot.
. If excessive temperatures inside the combustion chamber indicate poor combustion due to a clogged LDO screen or inadequate air for combustion, it shuts off the gas flow to the pilot and burner.
In cases where a shutdown is due to an LDO screen blockage, after cleaning and reinsertion of the screen, the water heater may be restarted. In all cases after a flammable vapor ignition incident, a qualified service technician should inspect the water heater. Minor component replacement may be required. In the unlikely event of a sustained incident, major components or even the entire water heater may need to be replaced.

Quality performance from the water heater experts
Our new C3 TechnologyT gas water heaters will meet the new ANSI standards and will continue to deliver the same outstanding quality and performance you have come to expect from our products.
Start-up will be easier, too. All new C3 TechnologyT gas water heaters come equipped with a sight glass and an easy-to-light piezo ignitor, a convenient advancement compared with traditional gas water heaters. Installation procedures, including placement of the unit, gas piping, water piping and venting, will remain the same, with few exceptions.
Combustion air port with lint, dust and oil (LDO) screen

Cutaway view of Corderite flame arrestor

Last updated 03/27/2015