Bradford White Water Heater Error Code 26

Error code 26 on a Bradford White water heater indicates that the vent safety switch has opened due to excessive heat detected at the first pass collector. This switch is a thermal protection device positioned in the flue/venting path that monitors temperature during combustion. When the switch detects temperatures at or beyond its threshold, it interrupts operation to prevent damage or hazard. Upon triggering, the gas valve closes immediately, the blower continues running through a post-purge cycle to clear residual combustion gases, and the unit enters a hard lockout state requiring manual intervention before the heater will restart.

The first pass collector is the initial section of the heat exchanger where combustion gases travel after leaving the burner. Overheating in this area typically points to restricted flue gas flow, combustion problems, or blocked venting that traps heat in the collector rather than allowing it to exhaust properly. Because this is a hard lockout, simply cycling power will not reset normal operation. The unit must be manually reset, and the underlying cause must be identified before doing so.

The first diagnostic step is to inspect the vent safety switch itself and assess whether temperatures have actually reached 350 degrees Fahrenheit in the collector. If there is physical evidence of extreme heat such as discoloration, melted components, or deformed venting materials, the unit should not be reset without contacting technical support. Resetting without addressing the root cause risks repeat triggering of the switch or more serious heat damage to the appliance and surrounding installation.