A.O. Smith Error Code E2: Dry Fire Protection
How to Fix A.O. Smith Code E2
- Step 1: Check that the main water supply valve to the house and the shut-off valves to the water heater are fully open.
- Step 2: Inspect the inlet water filter (if equipped) and clean it if it's clogged. The filter is usually located on the cold water inlet line to the unit.
- Step 3: Try resetting the water heater by turning it off and then back on. Some models have a reset button. If the error reappears, call a qualified technician.
What Does A.O. Smith Error Code E2 Mean?
The E2 error code on your A.O. Smith tankless water heater indicates a 'Dry Fire Protection' lockout. This safety feature is triggered when the unit senses the burner is firing without adequate water flow to cool it. The heater's control board monitors temperature sensors, and if the temperature rises too rapidly or exceeds a set limit, it assumes a dry-fire condition and shuts down the unit to prevent damage. This is important because running a tankless water heater without sufficient water flow can cause the heat exchanger to overheat and potentially crack or rupture. A cracked heat exchanger can lead to water leaks and, in some cases, carbon monoxide production if combustion gases are not properly vented. The E2 error is a protective measure to prevent these issues. The unit will remain locked out until the problem is resolved and the error is cleared.
Common Causes of A.O. Smith Code E2
- Low water pressure or flow rate to the unit.
- A blockage in the water inlet filter or supply lines.
- Air trapped in the heat exchanger.
- Faulty flow sensor or thermistor.
- Scale buildup inside the heat exchanger restricting water flow.
Applicable A.O. Smith Models
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