Display shows COOL; the heater does not run until the water warms slightly.

Possible Causes

Water temperature significantly below set point, recently refilled Villeroy & Boch spa with cold water, sensor detecting rapid temperature drop.

Safety: Normal protective function; no internal repair is usually needed.

Allow spa to warm: Keep the cover on the Villeroy & Boch spa and allow the system to gradually warm the water. COOL will clear automatically.
Check set temperature: Ensure the set temperature is appropriate and not extremely low.
Verify circulation: Confirm that the circulation pump is running to help distribute heat.

If COOL remains for an extended period and the spa does not heat, investigate heater and sensor faults.

Very Easy 1/5