How to Troubleshoot "C2 11" on a Tankless

A tankless water heater heats water as it passes through the device rather than in a tank.

Paloma's tankless water heaters have a display screen that shows an error code shows an error code when a problem occurs. A common error code is a "C2 11," which is related to the gas flow to the water heater. A number of troubleshooting steps can be taken to determine the cause of the problem.

1. Check the gas shutoff valve. If the valve is not fully open, a "C2 11" or "C2 12" error code will display. The error will also appear if gas service to your location has been interrupted or if the gas is not the right kind. Contact your gas company in either case. Verify gas is flowing to the water heater.

2. Close the hot water faucet and turn off the remote control switch. Wait five minutes and open the hot water faucet again. If the error code remains, turn off the hot water faucet and the remote control again and contact a service representative.

3. Check the gas line. If air gets into the gas line, a "C2 11" or "C2 12" error code will display. Bleed the air from the gas line. Follow the procedure in Step 2.

4. Check the power supply. If the power supply is not grounded, the error code will display. Make sure the heater is set up properly and follow the process in Step 2.

5. Check the gas equipment. If the gas line, gas meter or gas regulator are not the correct setup for your water heater, the error message will display. Check the owner's manual to verify specifications. Follow Step 2.

6. Check the ventilation around the tank. If the tank is improperly vented, the error code will display. Verify that the heater has the right ventilation configuration. Follow Step 2.