Takagi water heater attempts to start but shuts down quickly with error 101 on the remote controller.

Safety first: Turn OFF power and gas before inspecting venting or internal components. Combustion issues can lead to carbon monoxide hazards; if you suspect exhaust leakage, stop using the heater and ventilate the area.

Steps:

• 1. Check air intake: For direct-vent models, inspect the intake terminal outside. Remove leaves, nests, snow, or debris. Ensure at least the minimum clearance around the terminal per Takagi installation instructions.
• 2. Inspect exhaust vent: Look for crushed, sagging, or disconnected vent sections. Make sure there are no obstructions at the termination (bird screens clogged, ice buildup, etc.). Correct any visible issues.
• 3. Verify vent length and configuration: If the vent run is very long or has many elbows, compare it to the maximum equivalent length allowed in the Takagi manual. Oversized or improperly sloped venting can cause poor combustion and should be corrected by a professional.
• 4. Check for recirculation: Ensure intake and exhaust terminations are properly spaced and not facing each other or in a confined alcove where exhaust can be drawn back into the intake.
• 5. Burner inspection: With power and gas OFF and the unit cool, remove the burner cover and visually inspect the burner surface for dust, lint, or corrosion. Gently vacuum and brush off loose debris without deforming burner ports.
• 6. Professional gas check: If error 101 persists, a licensed technician should measure inlet and manifold gas pressures and verify correct orifice and gas type (natural gas vs LP). Incorrect gas pressure or orifices must be corrected immediately.