Safety first: Before touching wiring, turn off power at the main breaker panel.

Step 1 – Check breaker: Locate the boiler’s dedicated circuit breaker and ensure it is in the ON position. Reset if tripped. If it trips again immediately, stop and call a technician.
Step 2 – Inspect service switch: Many boilers have a wall-mounted service switch nearby. Confirm it is ON and not defective. Replace if the switch feels loose or fails continuity testing.
Step 3 – Verify line voltage at boiler: Remove the electrical junction box cover on the boiler and check for 120V (or 240V, as applicable) at the incoming wires using a multimeter. Only do this if you are trained to work on live circuits.
Step 4 – Check internal fuse: With power OFF, inspect the control board for a small replaceable fuse. Replace only with the same type and rating. If it blows again, there is an internal fault that needs professional diagnosis.
Step 5 – Inspect wiring connections: Tighten any loose wire nuts or terminal screws in the boiler’s power compartment.

Warning: If you are not comfortable working with live electrical circuits, contact a licensed electrician or boiler technician.

Boiler will not start at all; no lights or display, completely dead.

Possible Causes