Yacht Sauna Consumes Too Much Power

While underway or when many onboard systems are active, a yacht’s electrical system can be heavily loaded. If the sauna draws more current than expected—causing circuit breakers to trip or overloading the generator—it indicates a malfunction in the heater or electrical circuit. Below we explain the main causes and how to address them.
 

1. Heater not properly sized for sauna volume

Choosing the correct heater power is essential for efficient sauna operation. As a general guideline:

  • 1 m³ (35 ft³) of sauna volume ≈ 0.75 kW heater power, valid for well-insulated cabins without glass walls.
  • For cabins with glass panels, heavy walls, or weak insulation, required power may increase up to 1–1.3 kW/m³.

If the heater is not properly sized, problems can arise: too powerful a heater wastes energy and increases consumption, while a too weak heater runs constantly at full power, raising energy use and accelerating wear on the heating elements.

 

2. Stones positioned incorrectly or deteriorated

Sauna stones are crucial for heat transfer. If they are broken, too compact, or dusty, they obstruct airflow and force the heater to work longer, slowing cabin heating. To maintain optimal performance, it is recommended to replace stones every 6–12 months, create air channels between them, and remove broken or blackened stones.

 

3. Weakened or partially burnt heating elements

The heating elements generate the heat: if defective or partially burnt, they draw current irregularly, straining the system and slowing sauna warm-up.

Quick check:
Sauna off → remove stones → turn on → all elements should glow red.
If one does not glow → replace it (ideally all together).
 

4. Temperature sensor reading incorrectly

The temperature sensor is essential for proper heater operation: if oxidized or incorrectly positioned, it cannot read heat accurately, causing the heater to overcompensate and slow cabin heating. For reliable readings, the sensor should be placed about 160 cm (5 ft 3 in) from the floor, on the side opposite the heater, and free from benches or panels that could obstruct measurement.


5. Insufficient ventilation in the sauna cabin

If air circulation is inadequate:

  • the sauna does not reach the set temperature
  • the heater stays at 100% power → increasing energy consumption

To avoid this issue, ensure the lower air intake is open and the upper air outlet is free, allowing a constant and uniform airflow inside the cabin.

 

6. Oxidized wiring or faulty connections

On yachts, oxidation of terminals and wiring is quite common due to humidity and salt exposure. This can cause irregular heater operation, uneven consumption, and overall reduced efficiency.

To fix the problem, a certified electrician should inspect, clean, tighten, or replace faulty wiring to ensure safe and stable sauna operation.

 

7. Voltage fluctuations from generator or shore power

Voltage spikes or drops can reduce heater performance, slowing heating and increasing time at full power.

Solution:

  • check generator stability
  • consider dedicated stabilizers or power filters

 

8. Sauna door not closing properly

Even a small gap of a few millimeters allows heat to escape continuously. As a result, the sauna struggles to maintain the desired temperature, the heater remains on for long periods, and energy consumption increases significantly.

 

Typical power consumption for yacht saunas

For 4–6 person cabins, common heater sizes include:

  • 6 kW
  • 8 kW
  • 9 kW
  • 12 kW

→ Continuous operation usually indicates incorrect sensor readings or improper heater sizing.

 

If the sauna draws excessive or irregular current, struggles to heat the cabin, trips circuit breakers, produces burnt odors, or displays error messages, it is time to contact professional assistance. For technical support and original spare parts for your yacht sauna, you can contact Centro Italia Yachting. In Italy, the toll-free number is 800 931 931, while from abroad you can call +39 327 612 0605.