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

Safety: Use caution around line voltage. Turn off the breaker before opening any junction boxes.

Steps:

• 1. Check breaker: At the electrical panel, locate the boiler circuit breaker. Reset if tripped. If it trips again immediately, do not force it on; call a technician.
• 2. Verify service switch: Ensure the boiler's service switch (often mounted nearby) is ON. Replace if the toggle feels loose or does not stay in position.
• 3. Inspect wiring: Remove the boiler's electrical junction box cover and check for loose wire nuts or burned connections. Tighten or replace as needed.
• 4. Internal fuse: Some Slant/Fin controls have an internal fuse. With power off, locate and inspect the fuse; replace only with the same type and rating.

Call a professional: If power is present at the boiler but it remains dead, the control board or transformer may be failed and should be replaced by a technician.