Navien Error Code E761: Pump Aquastat Not Detected
Severity
Warning
Type
digital display
Estimated repair cost:$100 — $350(parts + labor)
Warning: Your Navien tankless water heater has stopped working due to a problem with the pump aquastat circuit. You'll have hot water issues until this is resolved.
How to Fix Navien Code E761
Step 1: Reset the Navien unit by turning it off and then back on. See if the error clears. This might resolve a temporary glitch.
Step 2: Check the system water pressure. Low water pressure can sometimes cause unusual sensor readings. Ensure it's within the normal range (typically 12-15 PSI; check your manual).
Step 3: If the error persists after resetting and the water pressure is normal, contact a qualified HVAC technician to diagnose and repair the issue.
How to Reset Navien Code E761
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 E761 mean?
The E761 error code on your Navien tankless water heater indicates that the unit's control board isn't detecting the pump aquastat. The aquastat is a sensor that monitors the water temperature near the pump. It's used to help regulate the pump's operation and prevent overheating. When the control board doesn't see a signal from this sensor, it shuts down the unit as a safety measure. This prevents potential damage to the pump or other components. Basically, the Navien is saying it can't 'see' the pump's temperature sensor, so it's locking out to protect itself.