Rinnai Error Code 15: Rinnai Code 15 - Hot Water Temperature Too High
Severity
Warning
Type
digital display
Estimated repair cost:$100 — $250(parts + labor)
Warning: The water heater has shut down due to excessively high water temperature. This could indicate a problem that might lead to scalding or damage to the unit.
How to Fix Rinnai Code 15
Step 1: Check that multiple hot water taps aren't running simultaneously, overwhelming the unit's capacity.
Step 2: Reduce the temperature setting on the Rinnai unit to a lower setting (e.g., 120u00b0F or 49u00b0C).
Step 3: If the error persists after these steps, contact a qualified HVAC technician to diagnose and repair the unit.
How to Reset Rinnai Code 15
Turn off the unit using the power button on the front panel.
Turn off the gas supply valve.
Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
Restore power at the breaker, then open the gas valve.
Turn the unit back on. If the error returns, the underlying issue needs repair.
What does 15 mean?
Rinnai error code 15 indicates that the hot water temperature inside your tankless water heater has exceeded its safety limit. This triggers a safety shutdown to prevent scalding and potential damage to the unit. Several factors can cause this, but it usually boils down to a problem with the temperature sensors, the flow rate of water through the unit, or issues with the burner firing rate. When the water gets too hot, the unit locks out and displays this error code, preventing further operation until the issue is resolved. This is a safety feature, so it's important to address the underlying cause rather than just resetting the unit repeatedly. Ignoring this error could lead to scalding water or permanent damage to your Rinnai tankless water heater.