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How Much Electricity Does an 8kW Self-Modulating Tankless Electric Water Heater Use?

October 17, 2024

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An 8kW self-modulating tankless electric water heater uses up to 8 kilowatts (kW) of electricity when operating at full capacity. However, because it’s self-modulating, the heater adjusts its power usage based on the amount of hot water needed. For example, if you’re using a small amount of hot water, it may only use 4kW or less.

Electricity Consumption Formula

To calculate the electricity consumption, you can use this formula:

Electricity used (kWh) = Power rating (kW) × Time (hours)

If it runs at full power (8kW) for 1 hour, it will consume 8 kilowatt-hours (kWh) of electricity. At an average electricity rate of $0.12 per kWh, this would cost about $0.96 for one hour of usage. However, real-world usage typically results in lower power consumption due to the self-modulating feature.

Factors Affecting Energy Consumption

The actual electricity consumption can vary based on several factors:

  • Water usage: The more hot water you use, the more electricity the heater will consume.
  • Water temperature: Colder incoming water requires more energy to heat.
  • Duration: Longer hot water usage increases electricity consumption.

Conclusion

While an 8kW tankless water heater can use up to 8kW of electricity, the self-modulating feature helps optimize energy consumption, making it an efficient option for households. Real-world usage typically results in less power being used, saving you both energy and money over time.