Rinnai water heater gas pilot keeps going out: What to Check and What to Do Next

Use only checks that match the exact appliance or system and its official guide.

1. Check 1

   Read the model label and controller display without opening the cabinet, then open one normal hot-water tap only if there is no gas odor, smoke, water intrusion, or other hazard; do not call the burner a standing pilot until the model is identified.

   Expected result: Record whether the unit is a Rinnai tankless model with electronic ignition, whether the burner starts and then stops while the tap remains open, whether the flame goes out only when the tap closes, and any displayed diagnostic code or flashing indicator.

   Next step: Stop the demand after recording the pattern and use the model manual or qualified service path for the displayed code; do not repeatedly cycle the tap to force ignition.

   Stop if: Stop immediately for gas odor, smoke, abnormal combustion, a wet or submerged heater, a cracked vent, a shock, or any need to remove the front panel.

   Why this matters

   Why: A burner that goes out when demand ends is normal for a tankless Rinnai. Failure during continuing flow is an ignition, flame-proving, flow, gas, vent, or control symptom; the code and model determine which service path applies.

2. Check 2

   Before any further ignition attempt, smell from a safe position around the heater and near the floor, without touching switches or using a phone in the building.

   Expected result: Classify the result as no gas odor, a suspected or definite gas odor, or an odor that cannot be safely evaluated; note whether anyone feels unwell or a detector alarms.

   Next step: If gas is suspected, leave the building and contact the gas supplier or fire department from a neighbor's location; do not return to reset or relight the heater until cleared.

   Stop if: Do not operate switches, create a spark, relight, adjust a gas valve, or continue diagnosis when gas odor is present.

   Why this matters

   Why: A gas odor is an emergency, not a troubleshooting branch. Rinnai instructs users not to try to light an appliance, touch electrical switches, or use a phone in the building when gas is smelled.

3. Check 3

   From normal user access, verify that the heater's display or controller has power, that the known water isolation valves are open, and that one hot tap has a steady flow; do not remove covers or measure gas or electrical values.

   Expected result: Record a blank display, tripped breaker, loss of water flow, weak or intermittent hot-side flow, a unit that ignites only at one fixture, or normal flow with repeated ignition failure.

   Next step: Restore only a clearly identified tripped breaker or fully closed water valve when safe and permitted by the model instructions; arrange service for a repeated trip, weak flow, or recurring ignition failure.

   Stop if: Do not open electrical compartments, bypass a breaker, adjust gas pressure, or operate a heater that has been underwater or has wet wiring.

   Why this matters

   Why: No power prevents electronic ignition. Insufficient or unstable water flow can prevent a tankless unit from recognizing demand or can stop it after ignition. Normal flow with repeated failure points away from a simple demand issue and toward gas, spark, flame sensing, venting, or control service.

4. Check 4

   From ground level or another safe position, inspect the exterior vent terminal and combustion-air opening for snow, ice, leaves, nests, debris, loose visible joints, or an obstruction; do not climb, disassemble the vent, or place hands near hot exhaust.

   Expected result: Record whether the termination is visibly clear, partially blocked, damaged or loose, exposed to recirculating exhaust, or impossible to inspect safely; note whether the problem began after weather, landscaping, or vent work.

   Next step: Remove only loose exterior debris that can be reached without tools, heat, or unsafe access; keep the heater off and call a qualified gas-appliance technician for any blockage, damage, clearance concern, or recurrence.

   Stop if: Do not enter the vent, move a terminal, change vent length or fittings, block exhaust, or work near hot exhaust or elevated access.

   Why this matters

   Why: Rinnai identifies blocked or improperly arranged venting and combustion air as causes of incomplete combustion or ignition/flame-proving problems. A clear exterior does not prove the entire vent or burner path is correct.

5. Check 5

   If the failure began during freezing weather, a power or gas interruption, or after vent or condensate work, inspect only visible external piping and drain terminations for ice, blockage, standing water, or a disconnected line; do not open the heater or drain trap.

   Expected result: Record frozen or blocked exterior pipes, a blocked condensate termination, water around the cabinet, a wet vent connection, or no visible change; note whether freeze protection had power and gas available.

   Next step: Keep the heater off when moisture, freezing damage, or a blocked drain is present and request qualified service; follow the exact owner manual for any approved freeze-protection or drain-down procedure.

   Stop if: Do not apply an open flame or improvised heat, pour chemicals into a condensate line, remove the condensate trap, or use the heater if any part has been underwater.

   Why this matters

   Why: Rinnai warns that vent termination or condensate drain blockages can cause operational problems, and that plumbing and valves may freeze even when built-in heater protection is present. Moisture inside the combustion or electrical area is a service condition, not a pilot adjustment.

6. Check 6

   Compile the model, gas type shown on the rating plate, controller code, ignition timing, hot-water flow pattern, power status, vent and condensate observations, and any recent installation or weather event for the technician; do not perform internal spark or flame-rod tests.

   Expected result: Record whether there is never a spark or flame, a visible flame that drops out, repeated code 11 or 12-type ignition/flame symptoms if shown, a gas-related code, vent or air code, or no code at all.

   Next step: Leave the unit off for a repeated failure and provide the complete record to a trained Rinnai service professional; use only model-specific manuals for any owner-level reset explicitly allowed.

   Stop if: Do not adjust the internal gas valve, remove the panel, disconnect flame-rod or igniter wires, test live voltage, or keep resetting a recurring code.

   Why this matters

   Why: Rinnai's technical diagnostic paths distinguish no spark, flame rectification, low or incorrect gas supply, venting and air restrictions, moisture, and control faults. These observations narrow service but do not authorize live testing or part replacement.