Today, I addressed an issue with a tankless water heater installed about two years ago. The client reported an error code 12, indicating an exhaust/gas problem. Upon inspection, I noticed a large icicle obstructing the vent. Using a heat gun, I carefully melted the icicle to restore proper ventilation. After ensuring the vent was clear, I conducted multiple tests by running various faucets. The error code did not reappear, confirming the issue was resolved. The water heater is now functioning correctly.
