Rinnai Error Code 11

What the code is telling you

A tankless heater only fires when hot water flows. The fan runs, the igniter sparks, the gas valves open and a flame rod confirms there's a flame. Code 11 means that sequence ran and the flame never showed up.

It helps to know the neighbors. Rinnai lists code 12 as "Flame Failure", which is a burner that lit and then went out. Code 10 points to an air supply or exhaust blockage. If the display has shown more than one of these codes, write them all down and give the full list to the technician. It narrows the search.

The usual causes

Rinnai's code 11 checklist starts with the boring stuff, and it's usually right:

• Gas isn't turned on at the heater, the meter or the propane cylinder.
• Wrong gas type or wrong gas pressure for the unit.
• A gas line, meter or regulator that's too small for the heater.
• Air in the gas lines, which needs bleeding out.
• Dip switch settings, grounding, the igniter and the wires that feed it.
• Gas solenoid valves, burners not seated, or debris and condensation on the burner surface.

Rinnai's newer troubleshooting guide adds a loose "floating" flame rod and carbon or white buildup on the electrode and flame rod, and it gives technicians a 3.5 mm spark gap to check.

What you can safely check yourself

1. Make sure the house has gas. Light a stove burner or check another gas appliance. If nothing works, it's a supply problem for the utility, not the heater.
2. On propane, check the tank gauge. Rinnai's list starts with gas being on at the cylinder and also calls for bleeding air from the lines, and air gets into the lines when a tank runs dry. Refill first, then expect the lines to need purging.
3. Find the gas shutoff on the pipe going into the heater. The handle should run in line with the pipe.
4. Look at the vent terminal outside. On the RL75i and RL94i, Rinnai's technical sheet lists restrictions in air flow around the unit and the vent terminal under code 11. Snow, leaves, a wasp nest or a bush grown over the cap can all do it.
5. Think about recent changes. A new gas range, dryer or generator on the same line can leave the heater short of gas, which is the undersized-line item on Rinnai's list.
6. Turn the heater off at its controller, turn it back on and open a hot tap. If code 11 clears and the burner lights, keep an eye on it. If it comes straight back, stop resetting it and book a technician.

When to call a technician

Anything that means opening the cabinet is a technician job: measuring gas pressure at high fire, testing the solenoid valves, cleaning or tightening the flame rod, or changing dip switch settings. Rinnai's guide gives technicians a resistance check of 18 to 22 ohms for the gas solenoid, which needs a meter and the right model data.

For budgeting, HomeGuide puts tankless water heater repairs at $300 to $1,300 on average and an igniter replacement at $75 to $350.

RL75 and RL94 owners

The RL75i and RL94i technical sheet lists code 11 as "No Ignition" too, and adds checks for low water flow in a recirculating system, foreign material in the combustion chamber or exhaust, and scale hot spots on the heat exchanger. If you run a recirculation pump and the code shows up mostly at night or with tiny draws, mention that to the tech.