When your water heater stops working suddenly because of some internal problems, that can surely inconvenience you with your daily routines. But what if it keeps displaying error code 11 on the display and won’t operate?
If your Rheem tankless water heater is displaying code 11, there could be a few things causing this error code. The code indicates ignition failure mainly due to restricted gas flow to the ignition system, defective gas control assembly, bad circuit board, defective main burner and a defective ignitor.
Don’t worry because, in this guide, I’ll take you step-by-step on troubleshooting and fixing that problem.
But before further troubleshooting, you should ensure you reset your water heater. If you haven’t reset it yet, see our ‘how to reset tankless water heater’
Possible Causes & Solutions for Rheem Tankless Water Heater Code 11
| Problem | Main Fix |
| Restricted Gas Flow | Open valve completely or replace gas valve |
| Defective igniter | Replace igniter |
| Defective circuit board | Replace circuit board |
| Defective main burner | Replace burner |
| Defective gas control assembly | Replace gas control assembly |
Restricted gas flow
The first thing you want to do is check the gas supply to the water heater. Is the gas valve open? Ensure valves are open. It doesn’t have to be open; it must be open ultimately to allow the gas to flow freely to the ignition.
In many cases, homeowners think it’s ok to open the gas valve partially, but that usually prevents your tankless water heater from igniting.
Another possible cause is the level of gas in the tank. If insufficient or low gas levels are in the gas tank, your heater won’t ignite.
Solution
To resolve this problem, open the gas valve completely. The gas handle has to be perpendicular to the gas line. If the errors don’t go, that can mean you still don’t have gas flowing to the ignitor, and this is what you should do.
If a local utility gas company supplies you, call them and find out if there is no interruption in the gas supply.
After you have ruled out ‘restricted gas supply,’ you might have a defective gas valve. Gas valves, if defective, can be replaced. If you believe your gas valve is stuck or defective, watch this video on replacing a gas valve on a Rheem tankless water heater.
Defective ignitor
If nothing above works, then you might have a defective ignitor. An ignitor is a small surface that becomes red hot to light up a flame.
If the fan is running, but the igniter doesn’t spark, check the voltage on the igniter. For this test, you need to cycle your heater to initiate ignition. Measure the voltage across the connector wires of the connector. The normal range should be between 108 to 132 VAC.
If an ignitor is defective, there will be no spark. Usually, a bad ignitor will be visibly cracked.
If there the ignitor does have voltage on initiation, start by removing the cover plate to inspect the igniter.
If you are DIY and interested in self-troubleshooting, you can use a multimeter to test the igniter for continuity.
Ensure also that the electrodes are not damaged. If they are damaged, the solution is to replace them. Otherwise, if they look dirty, clean them if they are dirty. Also, ensure that the wiring is intact.
The fix
If you have a defective ignitor, you need to replace it. You cannot temporarily fix a hot surface ignitor.
- External digital thermostatic control with LED display (+/1 degree accuracy)
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- Durable Copper immersion two heating elements, field Serviceable. Flow Rate- up to 4.4 GPM
- Simple installation – bottom 3/4 inch NPT water connections
- Threaded for easy replacement, simple installation, digital temperature display
If there is no voltage across the igniter, replace the printed circuit board. Otherwise, replace the entire ignitor assembly if there is voltage and the electrodes are clean and not damaged.
Defective circuit board
If the heater fan runs and the igniter sparks but the main burner fails to ignite
Measure voltage across the gas inlet solenoid. Measure voltage across its connector wires. The normal range is 90-120 DVC.
If there is voltage across the inlet solenoid valve, go on to measure the voltage on solenoid valve #1. The normal range is -120 DVC.
And if gas solenoid # has voltage, go on to measure the voltage across gas solenoid valves #2 and #3. If there is no voltage on any of them, replace the circuit board to fix the problems.
Otherwise, if there is voltage across all the wires and are within the normal range of 90-120 DVC) go a step further to troubleshoot this problem.
Measure voltage across the Proportional Gas Flow Regulating Valve. The normal range is between 1.5 to 14 DVC. If the voltage exceeds range, you still need to replace the circuit board. But if the voltage is within the normal range, the problem could be with the gas control assembly.
A defective gas control assembly
If you have a defective gas control assembly, it can cause an 11-code error. For troubleshooting a malfunctioning gas control assembly, start by measuring the resistance of the gas inlet solenoid valve. Normal should be 0.8 to 2.4 ohms. If there is no resistance, the problem is probably with the gas control assembly. In that case, you need to replace it.
Otherwise, if the resistance is within the normal range on the gas inlet solenoid valve, go on to measure the resistance of the solenoid valve #1, #2, and # 3.
The expected resistance should be between 0.8 to 2.4 ohms in all three. You must replace the gas control assembly if the measured resistance is out of range. If there is normal resistance, you might have a faulty main burner.
Defective main burner.
To investigate whether or not you have a faulty main burner, you must first measure the resistance across all gas solenoids and be within the normal range in all cases.
Then measure the resistance across the PGFR (Proportional Gas Flow Regulating Valve), and if there is normal resistance which is supposed to be between 40 and 80 Ohms, you’ll have to replace the main burner.
However, if resistance is out of range here, you must replace the Gas control assembly.
Final Thoughts
After going through this troubleshooting guide, we hope you have fixed your Rheem tankless water 11 error code. If not, we highly recommend that you call for professional help.
