How to Fix / Troubleshooting

Safety: Use caution when working on line voltage. Turn off the breaker before opening electrical compartments.

Steps:

1. Check breaker: Verify the dedicated breaker is not tripped. Reset if necessary and see if it holds.
2. Inspect junction box: Open the heater's electrical junction box and confirm incoming power is present and connections are tight.
3. Test internal fuse: Some Lochinvar controls have an internal fuse. With power off, check and replace if blown with the same rating.
4. Check transformer: Measure low-voltage output from the transformer or power supply board. Replace if no output is present.
5. Replace on/off switch or control: If power is present but the control does not power up, replace the switch or main control board as needed.

Lochinvar water heater does not start; no lights or display, completely dead.

Possible Causes