Quick answer
Rinnai code 11 means the tankless water heater tried to light and did not ignite. Check the simple causes first: the gas valve to the heater is open, other gas appliances work, a propane tank is not empty, and after new gas work the line may have air in it. Turn the heater off and on and try a hot tap again. A blocked intake or exhaust vent can also cause it. If code 11 continues, the igniter, flame rod, gas valve or gas pressure needs a technician. Call (888) 217-6781 to reach a plumbing company taking calls in your ZIP.
Follow the short menu, then your 5-digit ZIP. The line goes quiet for a few seconds while it connects; stay on. If it does not connect, call once more: companies taking calls change minute to minute.
Written & reviewed by Marcus ReedIICRC WRT
Reviewed November 4, 2026· Next review May 2027
Rinnai tankless water heaters show a code on the controller when something stops them from working. Code 11 is one of the most common: the unit tried to ignite and did not see a flame.
Check These First
- 1The gas valve to the heater: the handle should be in line with the pipe.
- 2Other gas appliances. If the stove or furnace will not light either, the gas supply is the problem. Contact the gas utility.
- 3Propane. A low or empty tank is a frequent cause. Check the gauge.
- 4New gas work. After a meter swap or new line, air in the line can cause code 11 for a few tries.
- 5The vents. Intake and exhaust terminals outside must be clear of snow, leaves and nests.
- 6Power cycle the heater and open a hot tap again.
If It Keeps Coming Back
| Cause | Who fixes it |
|---|---|
| Gas pressure too low or line undersized | Plumber or gas technician |
| Failed igniter | Technician |
| Dirty or failed flame rod | Technician |
| Gas valve fault | Technician |
| Condensate or venting issue | Technician |
Tankless heaters need a high gas flow, so a line that ran a tank heater may be too small. See tankless vs tank water heater.
Talk to a plumber about this
One call reaches a plumbing company taking calls in your ZIP.
Safety
If you smell gas, do not touch switches; leave and call the gas utility from outside.
The Call
Call when the gas supply is fine and code 11 keeps returning. See tankless water heater no hot water. (888) 217-6781 connects you to a plumbing company taking calls in your ZIP. Follow the short menu, enter your 5-digit ZIP and stay on while it connects; if it does not connect, call once more, because the companies taking calls change minute to minute.
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Frequently Asked Questions
What does code 11 mean on a Rinnai?
NoIgnition: the heater attempted to light the burner and did not detect a flame.
How do I fix code 11 on my Rinnai?
Make sure the gas valve is open and gas is reaching the house, the propane tank is not empty, and the vents are clear, then power cycle it. If it continues, the igniter, flame rod, gas valve or gas pressure needs service.
Can low gas pressure cause Rinnai code 11?
YesUndersized gas lines, a failing regulator, or several gas appliances running at once can starve a tankless heater, which needs a high gas flow.
Sources
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Disclaimer: HearthDry is an independent educational resource. This article is for informational purposes only and does not constitute professional, legal, or insurance advice. Consult licensed professionals before making decisions about your property or insurance claims.
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