Igniter
Price the ignition part only after confirming the model number and connector.
Error Code: Rinnai 11
What it means: Rinnai error code 11 indicates an ignition failure — the unit attempted to light the burner but could not establish a confirmed flame within the ignition trial period. Rinnai tankless water heaters (V-series, RU-series, RUC-series) attempt 3 ignition trials; if all fail, the unit locks out with Code 11 displayed on the controller. The unit must be reset by pressing the On/Off button or cycling power. Code 11 can be caused by gas supply issues, igniter problems, or sensing circuit failures.
Common Causes
- Gas supply not open or air in line — The most common cause on new installations or after any gas interruption. The manual shutoff valve must be fully open. Air purging requires multiple reset attempts.
- Low gas pressure — Rinnai requires 3.5” W.C. minimum inlet pressure for natural gas (8.0” W.C. for propane). Pressure drops from shared gas runs or undersized meter cause Code 11.
- Dirty or failed flame sensor — Rinnai uses a flame rod sensor. A contaminated rod does not pass adequate microamps to confirm flame, causing the board to cut gas and log Code 11.
- Spark igniter failure — Carbon-fouled spark electrodes or a cracked ceramic insulator prevent reliable ignition spark.
- Blocked or disconnected vent — A blocked exhaust vent causes the unit to detect exhaust backpressure and prevent ignition. Common on horizontal vents that develop ice blockages in cold climates.
- Water flow below minimum — Rinnai requires minimum 0.5–0.75 GPM flow to activate. A low-flow fixture or partially closed shutoff may not activate the unit, which presents as ignition failure if the burner never fires.
Diagnosis Steps
- Check water flow: open a hot water tap fully. The unit should activate (hear the gas valve and igniter). If nothing activates, the flow is below the activation threshold — check for partially closed isolation valves.
- Verify gas supply: confirm the manual gas shutoff is open. Check other gas appliances. For a new installation, attempt 5–8 reset cycles to purge air from the line.
- Inspect the venting: for horizontal PVC-vented units, look at the exterior termination cap. Verify it is not blocked with ice, debris, or bird nests. Check the concentric vent pipe for disconnected joints.
- Access the combustion chamber (power off and gas closed): inspect the spark electrode. The electrode tip should be free of carbon and positioned approximately 3–4mm from the ground plate. Clean or adjust as needed.
- Inspect the flame sensor rod. Clean with 320-grit sandpaper or steel wool. The rod should be bright metal, not coated with white or brownish deposits.
Fix
For air-in-line: reset and retry 5–10 times over 15 minutes. Gas will eventually purge through. On propane systems, also verify the tank has adequate fuel — propane regulators can freeze up in very cold weather, restricting flow.
For a dirty spark electrode: clean the tip with fine sandpaper, verify the 3–4mm gap is maintained. For a dirty flame sensor: clean the rod. If the rod is corroded through or the ceramic insulator is cracked, replace the igniter/sensor assembly.
For blocked venting: clear the blockage and restore unrestricted airflow. If the vent termination cap has failed (warped, corroded), replace it with a Rinnai-approved termination kit.
Low gas pressure requires a licensed gas plumber to inspect the supply system and meter capacity.
Parts
| Part | Where to Buy |
|---|---|
| Rinnai igniter / flame sensor assembly | RepairClinic, SupplyHouse |
| Vent termination cap / kit | SupplyHouse |
| Isolation valve (ball valve) | Grainger |
Need Replacement Parts?
Before ordering, match the water-heating part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Technician
If Code 11 persists after purging air, cleaning the igniter, and checking venting, a licensed plumber or gas technician should inspect the gas supply pressure and valve operation. Rinnai gas valve replacement must be performed by a licensed technician — the gas valve is interlocked with pressure switches and the PCB in ways that require proper testing equipment to verify after replacement.