EN

Severity: Moderate

Rinnai Water Heater Error 11 – No Ignition – Burner Didn't Light

The Rinnai tried to light but never proved a flame – gas off, air in the line or low gas pressure lead.

Safety first · Consult a professional

Don't loosen gas fittings to 'bleed' air or open the unit to look at the igniter. If you smell gas, leave immediately, don't operate switches or use a phone indoors, and call 911 or the gas utility once you're outside. If a CO alarm activates, get everyone out and call 911.

  • Gas appliance: no DIY repairs. If you smell gas, leave the building, do not use switches and call your gas utility’s emergency line from outside.
  • Carbon monoxide is odorless. Keep a CO alarm near fuel-burning appliances; if it sounds, get everyone outside and call 911.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
No Ignition – Burner Didn't Light
Typical repair cost
$0–$1,500
DIY difficulty
Hard

Rinnai code 11 means no ignition: the heater went through its start sequence but the burner never lit, or never lit long enough for the flame rod to see it. Rinnai's diagnostic guide works through it in a fixed order – all gas valves open, air purged from the lines after installation, correct inlet gas pressure with every gas appliance in the building firing, the gas type on the rating plate matching what's piped in, then the igniter spark and a loose or dirty flame rod. That order reflects reality: the code is very common on brand-new installs, after propane runs out and after gas work. The owner's part is confirming gas is on and available; testing sparks, pressures and gas-type settings is for a licensed gas fitter or plumber.

How it looks on the display

Rinnai Water Heater / Boiler display showing error 11

Model families & display variants

Model familyShowsNote
Temperature controllers on non-SENSEI models (V-series, RL-series)11Displayed as a flashing number on the controller; some owners read it as 'code 11' or 'error 11'.
SENSEI condensing models (RU, RUR, RX)11Same meaning. SENSEI units often have a gas-type parameter in the settings, which a technician verifies.
Control-R app and Wi-Fi module11App alert mirrors the controller code; the heater itself must be reset locally.

Symptoms

  • Cold water and code 11 within seconds of opening a hot tap
  • Fan starts and you may hear ticking, but the burner never catches
  • Started right after installation, a gas meter change or a propane delivery
  • Gas range or other gas appliances also won't light
  • Heater was recently converted between natural gas and propane

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Gas valve closed at the heater or meter, or the propane tank empty or shut 26%
  2. Air still in the gas piping after installation, service or a propane run-out 18%
  3. Inlet gas pressure too low – piping sized for an old tank heater can't feed a 199,000 Btu/h tankless unit 16%
  4. Igniter not sparking: loose or cracked electrode, wrong spark gap, damaged wire or ignition module 12%
  5. Gas type mismatch – rating plate, orifice or gas-type setting doesn't match the supply 10%
  6. Flame rod loose ('floating') or dirty so a brief flame goes undetected 10%
  7. Gas valve or PC board fault 8%

Fix it step by step

Diagnostic flow: 111Gas smell? Stop.2Open every valve on the way3Prove gas is reaching the house4Read the rating plate5Listen during the start attempt6Reset once, then book a gasprofessional

  1. Gas smell? Stop.

    If there's any gas odor, don't attempt a restart – follow the safety box. Otherwise continue with the checks below.

  2. Open every valve on the way

    Check the manual shut-off right below the heater, the valve at the meter and, for propane, the service valve on the tank. Rinnai's first diagnostic step is simply making sure all of them are open.

    Tools: Flashlight

  3. Prove gas is reaching the house

    Light a burner on the gas range or check that the furnace fires. If nothing gas-fired works, call the gas utility or your propane supplier – the heater isn't the problem.

  4. Read the rating plate

    The label on the side of the heater states natural gas or propane (LP). If it doesn't match what your home uses, or someone recently converted the unit, the heater must not run until a technician corrects it.

    Tools: Flashlight

  5. Listen during the start attempt

    Open a hot tap and listen near the heater: fan plus ticking but no flame suggests gas isn't arriving; fan with no ticking points toward the ignition system. Tell the technician which you heard.

  6. Reset once, then book a gas professional

    Cycle the power at the controller and try again. If 11 returns, a licensed plumber or gas fitter should purge the line if needed, measure inlet pressure at full fire and check the spark gap (Rinnai specifies 0.138 in. / 3.5 mm) and flame rod.

How to reset 11

  1. Close all hot water taps and confirm gas is on and there's no gas smell.
  2. Turn the heater off with the power button on the temperature controller, then back on.
  3. Open a hot tap fully; the burner should light within a few seconds.
  4. If code 11 returns, stop and call for service rather than retrying repeatedly.

Where the parts are

Boiler: pressure gauge, ignition and flue – 11123456789
Boiler: pressure gauge, ignition and flue
  1. 1Flue
  2. 2Fan
  3. 3Heat exchanger
  4. 4Ignition electrode
  5. 5Gas valve
  6. 6Circulation pump
  7. 7Expansion tank
  8. 8Pressure gauge
  9. 9Temperature sensor

Repair options & costs

RepairDIY?Estimated cost
Open valve / propane refill with supplier leak check No $0–$150
Service call: purge gas line, verify gas type and pressure No $150–$280
Replace igniter or flame rod assembly and gasket No $180–$380
Replace gas valve or PC board No $400–$850
Upsize gas piping for the tankless heater No $500–$1,500

Rough US estimates; technician call-out fees vary by region. Not a quote.

When to call a technician

If the valves are open, other gas appliances work and a single reset doesn't clear code 11, call a licensed plumber or gas fitter. A heater that has shown code 11 since installation day belongs back with the installer, since line purging, sizing and gas-type setup are part of the installation.

Frequently asked questions

Why does my new Rinnai show code 11 on the first day?

New installations commonly still have air in the gas line, a valve that wasn't fully opened, or piping that's too small for the heater. All of these are installation issues the installer should correct.

Can a tankless heater run on my old tank heater's gas line?

Often not. A tank heater might use around 40,000 Btu/h while a whole-house Rinnai can draw close to 200,000 Btu/h, so the old line may be too small. Low pressure at full fire causes codes 11 and 12.

I switched from natural gas to propane – is that why I see code 11?

It could be. The heater must be built or properly converted for the gas it receives, including the gas-type setting. Running the wrong gas is unsafe, so have a qualified technician confirm the conversion.

How is code 11 different from code 10?

Code 10 is about air supply or exhaust being blocked. Code 11 is about the burner failing to light, which usually traces back to gas supply or the ignition parts.

Sources