Knowledge Base

How Many Watts Does a Hot Water Heater Use? (Power Consumption Test)

By:Michael Johns

water heater power header

On this page, you will find out how many watts a hot water heater draws.

Hot water on demand. It’s such a convenient world we live in now. No longer do we have to wait for a tank to refill and warm up before taking a shower. At the flick of a switch, you can get steaming hot water whether it’s in the kitchen sink or in the bathroom. But what power consumption does this convenience take?

Below we will discuss and test electric water heater wattage, explain how to work it out for yourself, and calculate the total electricity required.

How Many Watts is a Hot Water Heater?

The average hot water heater uses between 2000 and 3000 watts.

The exact number depends on the size and model of your hot water heater. For example, a small 2 gallon water heater uses 2000W, while larger 3 gallon units use 3000W or more!

Why do they consume so much? Well, the internal heating element is what needs so much electricity. It takes a lot of power to get the element hot to transfer heat into the water supply. It’s a similar electricity usage to a kettle.

The larger the capacity of the electric water heater, the higher the power consumption. This is because it has a larger heating element to run in order to produce more hot water.

How to Find Out Your Hot Water Heater Wattage

There’s 3 ways you can work out the wattage of a hot water heater.

  1. Check Product Specification

The quickest way is to look at the hot water heater’s specification. The watts (W) is usually written on a sticker on the base of the appliance. If not, you can check the user manual or the manufacturer’s website for technical details.

water heater power spec
  1. Use a Wattmeter

A wattmeter is brilliant for getting a live wattage reading and tracking total energy usage of any appliance. You can plug it into your hot water heater to get instant information. 

  1. Wattage Formula or Calculator

If you know the amperage and voltage of your hot water heater you can use this to find the maximum watt rating. Simply use the formula Amps x Volts = Watts. Or you can head over to the ‘Watt Calculator’ to work this out.

Hot Water Heater Wattage Examples

Let’s take a look at specific examples of how many watts a hot water heater draws. Below is a collection of modern hot water heaters with their listed power ratings.

Hot Water Heater ModelPower Rating (Watts)
Ariston Andris Lux Undersink Water Heater 102000
Ariston Andris Lux Undersink Water Heater 153000
Triton T30i Instaflow Handwash Oversink Water Heater3000
Zip Hydroboil Hs005 Wall-Mounted Beverage Boiler2200
Zip Aquapoint Iii Ap3/10 Electric Water Heater2000
Zip Ap3/15 Electric Water Heaters2000
Handyflow 5 Oversink Water Heater2000
Perfect 35 Undersink Instant Water Heater3500
Redring Stored Undersink 6 Water Heater 1500

As you can see, the power ratings vary between different hot water heaters. So you should take the time to check your own appliance.

How Much Electricity Does a Hot Water Heater Use?

You can use hot water heater wattage to work out how much electricity it uses. Plus this can be useful in understanding how much it costs to run your hot water heater.

A watt (W) is a measurement of power at a single point in time. A watt-hour (Wh) is the total amount of electricity used in an hour. For example, a hot water heater drawing 2000W uses 2000Wh when running for an hour.

Happily, electricity bills are recorded in kilowatt-hours (kWh). A kilowatt is simply 1000 watts. So a 2000W hot water heater running for 1 hour uses 2kWh.

Let’s say your water heater actively runs for 20 minutes a day. This means it uses about 666Wh or 0.666kWh electricity a day. That’s 20kWh a month and 240kWh a year. 

That’s a rough electricity cost of $0.10a day or $36 a year to run an electrical hot water heater for 20 minutes a day.

Using a Hot Water Heater Off-Grid

If you’re planning to use your hot water heater in an off-grid situation like a power outage, the information above is critical. It enables you to install the right electrical equipment and know how long it can run.

You can either use a power inverter, portable power station, or generator to generate AC electricity. 

To make sure everything runs smoothly you should check two things on this equipment – wattage capacity and total energy capacity. 

Your power source, like an inverter, should have a wattage capacity of at least 20% more than your hot water heater. This ensures it will be able to deliver enough power as they are never 100% efficient. 

Secondly, you need to ensure your energy source, like a battery, has enough energy to run the hot water heater for the required amount of time. As we already know, it will use about 666Wh electricity for 20 minutes. This is the equivalent to 55.5Ah on a 12V battery.

How Many Watts Does a Hot Water Heater Use Summary

I hope you now have a clear understanding of how many watts a hot water heater uses.

As with any type of electrical heater, these devices use suck up a lot of electricity. There’s no avoiding it due to how the heating element operates. If you’re worried about your energy consumption then only run your tap or shower when strictly necessary. When looking to install a power backup or off-grid solution, ensure you’re system has the required capacity to deal with the power spike.