Rheem Tankless Error Code 14: Over Heat Limiter Active (Meaning, Causes, Fixes)

What the code means

Rheem's High and Super High Efficiency Tankless Troubleshooting Manual (AP21822) explains that the water heater has an Over Heat Limiter (OHL), and if the OHL has been activated or broken the heater shows 14 on the built-in controller or remote. Rheem adds that this is normally caused by an inadequate or wrong gas supply and/or venting. The manual's check method has a technician turn power off, reseat the control board connector and the OHL's own connector, and see whether the code clears. If it doesn't, they measure the OHL's resistance: if it reads out of Rheem's range, the manual's answer is to replace the water heater, not just a part; if it reads normal, the control board is replaced. Rheem's older Technical Service Bulletin for RTG 74 tankless fault codes (indoor, outdoor and heavy duty models) lists 14 as Overheat Wrap Fault, with remedies covering high and low fire manifold gas pressure, a gas type that doesn't match the unit, heat exchanger cracks or separations, an incorrect high altitude chip, restricted airflow around the unit and vent terminal, and foreign material in the combustion chamber or exhaust piping. Code 14 is different from code 15, which Rheem uses for excessively hot water (above 207°F for more than 15 seconds).

Likely causes

• Inadequate or wrong gas supply, which Rheem names as a normal cause, including high or low fire manifold pressure that is out of spec
• A gas type that doesn't match the heater (for example a natural gas unit on propane, or the reverse)
• Venting problems, restricted airflow around the unit or at the vent terminal, or foreign material in the combustion chamber or exhaust piping
• A cracked or separated heat exchanger, or an incorrect high altitude chip (older RTG models, per Rheem's fault code bulletin)
• A loose connection at the control board or Over Heat Limiter connector
• A broken Over Heat Limiter, which Rheem's chart resolves by replacing the unit, or less often a failed control board

Safe DIY checks

1. Write down the code and your model number (from the rating plate). Turn the heater off at its power switch or plug before doing anything else.
2. Check outside at the vent and air intake terminals for blockage such as leaves, nests, snow or ice, and make sure nothing is stacked against or around the heater that blocks airflow.
3. Check that the vent pipes are still connected and haven't been knocked loose or crushed.
4. Confirm the heater was installed for the gas you actually have. The rating plate says natural gas or propane; a mismatch needs a professional conversion or replacement, not a setting change.
5. Restore power once and see whether the code returns. If 14 comes back, stop using the heater and call for service. Don't keep cycling power, since Rheem treats this as a safety device that tripped.
6. Don't open the sealed combustion section or adjust gas pressure yourself. If you smell gas, leave the house and call your gas utility from outside.

Parts that commonly fix it

Always match the part number to your exact model.

Related codes

• 12 Rheem Tankless Water Heater 12
• 13 Rheem Tankless Water Heater 13
• 29 Rheem Tankless Water Heater 29
• 45 Rheem Tankless Water Heater 45
• 61 Rheem Tankless Water Heater 61

All Rheem codes →

Sources

1. Rheem High and Super High Efficiency Tankless Water Heater Troubleshooting Manual AP21822, pages 41-42 (14 Error Code: Over heat limiter is active, normally caused by inadequate/wrong gas supply and/or venting; reseat connector C and the OHL connector, check OHL resistance, replace the unit or the control board; 15 Error Code for comparison)
2. Rheem Technical Service Bulletin, RTG 74 Tankless Fault Codes (Indoor, Outdoor and Heavy Duty models): 14 Overheat Wrap Fault (manifold pressure, gas type, heat exchanger cracks, high altitude chip, airflow and vent terminal restrictions, foreign material in combustion chamber or exhaust)