Imperfect combustion
• Check the gas type of the water heater.
• Inspect the environment around the water heater. Determine how long the unit has been installed.
• Check the altitude/elevation of the area of where the water heater is installed.
• Check if there is any blockage in the intake air and/ or exhaust.
• If the water heater is installed as a direct-vent system, check whether there is enough distance between the intake air terminal and the exhaust terminal.
• Check if there is grease and/or dirt in the burner (Part #101) and the fan motor (Part #103), especially if the water heater has been installed in a contaminated area.
