Rheem Code 11: Tankless and Power-Vent Meanings

The Short Answer: Code 11 always concerns ignition on a Rheem gas heater, but what it means depends on the type. On a Rheem tankless, a flashing 11 means the burner didn’t light, and the owner’s manual first points to a gas valve that isn’t fully open. On a Rheem power-vent tank, code 11 means the control has locked out after failed ignition trials. Identify your heater, then follow its manual.

Which Rheem do you have?

Rheem tankless: code 11

The error chart in the RTG Use & Care manual (opens in a new tab) lists code 11 as “The gas shut-off valve is not fully opened,” with the remedy “Check shut-off valve and open completely.” That is the owner’s part; any other cause behind an 11 needs a technician. On condensing IKONIC models the matching code is A011, “Flame Not Detected From Flame Rod,” which Rheem’s service guide (opens in a new tab) says appears after repeated ignition attempts.

Code 11 on a tankless tends to show up in a few situations:

• After gas work or a new installation. A valve left partly closed, or air still in a new gas line.
• After the gas meter was turned off or replaced. Other appliances may relight on their own while the tankless can’t.
• On propane systems. An empty or nearly empty tank, or a closed tank valve.
• Without an obvious trigger. The igniter, flame rod, gas valve, or gas pressure may be at fault.

The RTG manual describes this reset sequence when an error code appears:

1. Turn off all hot water faucets.
2. Turn the heater off with the power button on the remote control, wait about five minutes, then turn it back on and open a hot faucet.
3. If the code remains, turn the faucet and heater off, unplug the heater for about 30 seconds, plug it back in, follow the chart remedy, then try again.
4. If the code is still there, note it and call for service.

Don’t keep cycling it beyond this. Each failed ignition attempt sends some unburned gas through the combustion chamber.

Rheem power-vent tank: code 11

Rheem’s power vent manual (AP23057) (opens in a new tab) lists code 11 as “System in lockout. Failed trial for ignitions,” shown as six flashes followed by one. The control makes three attempts to light before locking out. Rheem’s Technical Bulletin 1627 (opens in a new tab) explains that code 11 is a soft lockout lasting about five minutes. After repeated soft lockouts the control moves to a hard lockout (code 10), which is cleared only by turning power off and back on.

In other words, the heater will try again on its own after a short wait. If it keeps locking out, something is stopping ignition: gas supply, the igniter, flame sensing, or venting.

What you can check safely

• Find the gas valve on the pipe to the heater and make sure the handle is fully in line with the pipe, and check that other gas appliances work. If none do, contact your gas utility.
• On propane, check the tank level and that its valve is open.
• For power-vent tanks, check that the heater is plugged in and the vent termination outside is clear of snow, leaves, or nests.
• For tankless units, check the vent termination and the clearance in front of the air intake.
• Note how many flashes or which code you see and how often it recurs.

What the technician will check

On either type, the technician confirms gas pressure, watches an ignition attempt, and tests the igniter and flame sensor. On a power-vent tank they also check the blower, pressure switch, and vent, since these must prove airflow before the gas valve opens. On a tankless they check the gas valve, that the unit is set up for the right gas type, and that the gas line is large enough for the heater’s input.

Frequently Asked Questions

Q: The gas valve on my tankless is fully open. What now? A: Then the owner-level remedy in the manual is used up. Note the code and call a technician to check gas pressure, the igniter, and the flame rod.

Q: Why did 11 appear right after my new tankless was installed? A: New gas lines often contain air, and a valve may not have been fully opened. Ask the installer to come back. Clearing air from gas lines is installer work.

Q: What is the difference between tankless codes 11 and 12? A: Code 11 means the burner never lit. Code 12 means it lit and then lost its flame. See Rheem tankless error code 12.

Q: The power-vent heater cleared itself after a few minutes. Is it fixed? A: Not necessarily. Code 11 on a power vent is a temporary lockout, so it retries automatically. If it happens again, have the ignition and gas supply checked.