Water Heater Brochure

At A. O. Smith, we place the safety and

reliability of our products above all

else. By incorporating technologically

advanced safety features into every

model, we provide the assurance and

peace of mind that can only come from

an A. O. Smith quality product.

Air-Fuel Ratio (AFR) Sensor

A. O. Smith’s unique AFR sensor

monitors and maintains proper

combustion at all times. Together with

the onboard computer, this system will

adjust the fan motor speed to ensure

that air and fuel have a proper

mixture ratio, minimizing emissions

and maximizing efﬁciency.

Additional Safety Features

Freeze Protection:

Every heater in A. O. Smith’s tankless

lineup has an internal freeze protection

system, which is rated to protect the

HEAT EXCHANGER

IGNITER

AFR

FLAME SENSOR

BURNER

heaters when installed in sub-freezing conditions. This system works to keep water temperatures within the heat

exchanger from falling below a certain level, preventing freeze damage.

Hi-Limit Switch:

Ensures that water temperatures do not exceed safe levels. Before the water temperature can even reach these

unsafe levels, the hi-limit switch activates by disengaging the gas valves, effectively shutting down the water

heater.

PVC Venting:

Indoor condensing models have a thermistor and hi-limit switch that monitor the exhaust temperature. If the

exhaust temperature nears an unsafe limit, these features regulate combustion and can shut the heater down to

protect the integrity of the PVC vent material.

Overheat Cutoff Fuse:

Ensures that there are no breaches in the heat exchanger drum. In cases where enough physical damage might

have been done to the water heater to lead to a breach in the heat exchanger drum, the overheat cutoff fuse

reacts by shutting down the water heater if the surface of the heat exchanger retains too much heat.

SAFETY