HeatingCodesNoritz tankless error codes 11 and 12: ignition failure and weak flame
What Noritz says
In a post on its own website, Noritz lists error 11 as an ignition failure: "it means that your unit is not firing up to heat the water," which can be caused by insufficient gas supply, insufficient airflow or debris on the ignition plug. After you check that the gas is turned on, the company says to call a licensed contractor who will make sure the gas valve is open, the exhaust vent is unobstructed and the ignition plug is firmly attached and free of debris.
Error 12 means the unit has a weak flame and the water is not being heated properly. Noritz says that it is "similar to a code 11," caused by lack of gas or airflow, and that a contractor will likely take the same steps.
Noritz's other common codes
| Code | Meaning (per Noritz) |
|---|---|
| 11 | Ignition failure. Insufficient gas, insufficient airflow or debris on the ignition plug. |
| 12 | Weak flame. Lack of gas or airflow. |
| 16 | Sharp spike in outlet water temperature, often scale buildup. Descaling or a water softener may help. |
| 29 | Condensate drainage problem on condensing models: a blocked drain line or incorrect drain piping. |
| 73 | Improper circuit board settings. Noritz says to unplug the heater for 30 seconds and plug it back in. |
| F76 | Communication breakdown between two heaters connected with a Quick Connect Cord. Make sure only one remote is connected. |
| 90 | Combustion abnormality from an improper air and fuel mixture. Needs a licensed contractor. |
About this source
The Noritz post is dated November 16, 2015 and applies to Noritz tankless water heaters in general. It does not name model numbers, so details can differ between models. Your owner's manual is the authority for your exact unit. This page therefore stays at the level the company itself states.
Safe homeowner checks for Noritz tankless error 11 or 12
- Check that gas is onConfirm another gas appliance is working. If you have propane, check the tank. If you smell gas, leave and call your gas utility from outside.
- Check the exhaust and air intake outdoorsFrom the ground, clear snow, ice or debris at the vent termination. Do not remove the vent.
- Retry one hot tapTurn on one hot tap fully. If the heater does not fire or the code returns, stop.
- Call a licensed contractorNoritz says to contact a licensed contractor for these codes.
Frequently asked questions
Does Noritz say to reset the heater for error 11?
No. The reset advice in the post (unplug for 30 seconds) is for error 73. For 11 and 12 the post says to check that gas is on and call a licensed contractor.
What does error 29 mean?
A condensate drainage problem on a condensing model. It is a blocked condensate drain line or incorrect drain piping.
Do other brands use the same numbers?
Not reliably. For example Rinnai and Takagi have their own code tables, so use the one for your brand.
Sources
- How To Resolve The Seven Most Common Noritz Tankless Error Codes (blog, November 16, 2015) (Noritz) Covers: Noritz tankless water heaters in general. The post does not list model numbers, and some codes (for example 29) only apply to condensing models.
Safety note: this page is general information drawn from the sources above. Gas, combustion and line-voltage repairs belong to a licensed professional. Your own equipment's label and manual take priority over anything here. Read the full disclaimer.