How Many Watts Does A Tankless Water Heater Use? - Tankless Water Heater Power Consumption Explained

5 min read

If you are thinking of buying a new tankless water heater you might be wondering what the wattage of the device is. Average tankless water heaters use between 3,000 and 28,000 watts of electricity. The running wattage however is lower, because it doesn’t run on full power all the time. For an average tankless water heater you can expect it to be 80% (depending on the water temperature) of the wattage. 

The power consumption of a tankless water heater largely depends on it’s size and how often you use it in a day. If you use an 10 kW tankless water heater for one hour every day at 80% heat, you can expect it to consume about 8000 watt hours in an average day and 2,920 kWh per year..

It’s important to keep in mind that the exact power consumption varies depending on the model and size you choose. Age also plays a role when calculating the energy efficiency of electronic devices. Generally speaking, if you purchase a new instantaneous water heater, you can expect it to use less watts than an older model. 

Power Consumption Of A Tankless Water Heater Summarized

Average Power UsageTimekWh Used
8000 Watts
1 Hour
8000 Watts
1 Day
8000 Watts
1 Week
8000 Watts
1 Month
8000 Watts
1 Year

(Energy consumption is calculated based on an average usage of a tankless water heater.)

If you want to find out how much it costs to power your instantaneous water heater, you need to multiply the kWh used in a specific time period by your electricity rate. In 2024 the average price of electricity for residential customers in the US is currently $0.16 per kWh. Running an average tankless water heater for one year will therefore cost around $467.20. If you live in California, where electricity currently costs $0.26 per kWh it will cost you around 60 % more. In the State of Utah, which currently has the cheapest electricity in the USA at only $0.11 per kWh, you can expect to pay around 30 % less to power your tankless water heater. 

The power consumption of your tankless water heater is important to consider, when trying to save energy or planning a solar system. If you want to verify the exact wattage of your device, we recommend looking out for the EnergyGuide label on the packaging. 

Buying An Energy-Efficient Tankless Water Heater

As you can see, the operating costs for a tankless water heater can quickly sum up. If you are about to buy a new tankless water heater, we recommend choosing an energy efficient model. Keep an eye out for the ENERGY STAR labels. Unlike the EnergyGuide label, the ENERGY STAR label only marks devices that have proven to be particularly energy-efficient. 

Additionally, consider the following tips when purchasing your new tankless water heater:

  1. Research Before You Buy: Before making a purchase, it’s wise to do some research. Look for customer reviews and ratings to understand the performance and reliability of different models.
  1. Compare Energy Consumption: Check the energy consumption details of various models. Sometimes, spending a bit more on a more energy-efficient model can save you money in the long run through reduced utility bills.
  1. Size Matters: Ensure that the size of the tankless water heater fits your needs. Larger models often consume more energy, so buying a bigger size than necessary can be less efficient.
  1. Look for Advanced Features: Some modern tankless water heaters come with advanced features that help save energy. Features like programmable settings or eco-modes can make a significant difference in energy consumption.
  1. Calculate the Total Cost of Ownership: Remember to consider not just the purchase price, but also the long-term operating costs. An energy-efficient tankless water heater may have a higher upfront cost but can lead to significant savings over its lifetime.

By choosing an energy-efficient tankless water heater, you are not only saving money but also contributing to a more sustainable environment. Always balance your immediate needs with long-term efficiency and costs.

Power Your Tankless Water Heater With A Solar System

Did you know that you can produce enough electricity to continuously power a tankless water heater with 5 solar panel(s)? That’s because a standard 400 watt solar panel in the USA generates on average around 600 kWh of electricity per year. If you live in the northern parts of the country, you can expect a slightly lower output, while the output in the southern parts of the country, especially in Texas and Arizona, will be slightly higher. 

Factoring all other devices you already have in your house, a solar system might save you tens of thousands of dollars over a period of 20 years. With these savings, the decision to go solar becomes not only environmentally responsible but also financially wise.

When considering the switch to solar, it’s important to get the best deal and the right setup for your needs. That’s where Quote For Solar comes in. By choosing Quote For Solar, you can easily request quotes from 3 local solar installers near you. Don’t miss out on the opportunity to power your tankless water heater and other appliances in a cost-effective and sustainable way. 

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