Water Cold but Max Temp Reached and the heater output indicator (blue) is lit

Symptom

The most noticeable symptom in this scenario is that the heater fails to produce hot water, even though the system displays a message indicating that the maximum temperature has been reached. Additionally, the heater output indicator (blue light) is illuminated, which typically signals that the heater is functioning.

However, despite these indications, the water remains cold.

Cause

Several potential causes could explain why the heater isn’t producing hot water despite the system suggesting otherwise. Here are the most common causes:

• Heater Thermostat is Open: This occurs when the heater’s internal thermostat is in an open position, which means it is not allowing the heater to function properly.
  
  

• Heater Isolation Switch is Off: The heater’s isolation switch, which controls the heater's connection to the electrical system, may have been turned off, preventing the heater from generating any heat.
  
  

• Heater Element is Faulty: The heater’s element itself may be defective. The element is responsible for heating the water, and if it is damaged or worn out, the heater will not produce any heat, even though the system might indicate otherwise.

Solution

1. Check if the Heater Thermostat is Closed: The first step is to confirm whether the heater thermostat is closed. You can do this by running off some hot water. If the heater continues to display “Max Temp Reached” without providing hot water, it may indicate that the thermostat is stuck in an open position. In this case, you may need to reset or replace the thermostat.
   
   
2. Use the Bypass Switch to Test the Heater: If the thermostat appears to be functioning properly, the next step is to use the bypass switch to test the heater’s performance. The bypass switch allows you to override the thermostat and test whether the heater element is working. If the heater still does not produce any heat when using the bypass switch, it is highly likely that the heater element is faulty and will need to be replaced.

Conclusion

If your heater is not heating, but the system displays that it has reached the maximum temperature, the issue likely lies with the heater’s thermostat, isolation switch, or element. By systematically checking each potential cause and testing the system, you can identify the problem and implement the correct solution to ensure your heater is back up and running efficiently.