Heater will not start at all – no display, no lights, no sounds.

Safety first: You are dealing with line voltage. Turn off the breaker before opening the heater’s electrical compartment.

Steps to troubleshoot no‑power condition:

• Check breaker and disconnect: Verify the pool heater breaker is ON and any external disconnect is closed. Reset if tripped; if it trips again, stop and call a professional.
• Inspect power wiring: Remove the electrical access cover and confirm that the supply wires are firmly attached to the heater’s terminal block and not burned or loose.
• Check internal fuse: Many Raypak boards have a small fuse. With power OFF, remove and inspect/ohm the fuse. Replace only with the same type and rating if blown.
• Test transformer: If you are qualified, restore power and measure voltage at the transformer primary (line) and secondary (24 VAC). If primary has power but secondary is dead, replace the transformer.
• Control board: If proper 24 VAC is present but the display is blank, the temperature control board is likely failed and must be replaced.

Warning: If you smell burning or see melted wiring, do not re‑energize the heater until inspected by a technician.