The world is moving into the electric age. We are shifting away from fossil fuels to renewable energy sources which generate electricity. This switch includes cars, cooking, and even boilers.
Modern central heating installations now have electrical boilers at the heart of the system. They are far more eco-friendly and efficient. In fact, they are 100% efficient! For every 1kW of electricity you use, you produce 1kW of heat. That’s great news but what’s to overall power consumption and how does it affect your energy usage?
Below we will discuss and test boiler wattage, explain how to work it out for yourself, and calculate the total electricity required.
How Many Watts is an Electric Boiler?
The average boiler uses between 6000 and 12,000 watts. That’s 6 to 12 kilowatts!
The exact number depends on the size and model of your electric boiler. For example, a smaller 20,000 BTU boiler uses 6000W, while a big 40,000 BTU boiler draws 12,000W or more.
You can clearly see that the size of your boiler directly impacts its power usage. A boiler is sized in BTU which is the volume of water it can heat in one hour. The higher the BTU number the more power it consumes. This is because it is able to heat a larger amount of water.
How to Find Out Your Electric Boiler Wattage
There’s 2 ways you can work out the wattage of a boiler.
- Check Product Specification
The quickest way is to look at the boiler’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. Often it can be marked in kilowatts (kW). A kilowatt is just 1000 watts. For example, 7kW is 7000W.
- Wattage Formula or Calculator
If you know the amperage and voltage of your boiler 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.
Boiler Wattage Examples
Let’s take a look at specific examples of how many watts a boiler draws. Below is a collection of modern boilers with their listed power ratings.
| Boiler Model | Power Rating (Watts) |
| Heatrae Sadia C600 | 6000 |
| Heatrae Sadia Amptec U1201 | 12,000 |
| Heatrae Sadia Amptec C1100 | 11,000 |
| Heatrae Sadia Amptec UF U901 | 9000 |
| Heatrae Sadia Amptec UF U601 | 6000 |
| Strom SBSP15c single-phase | 14,400 |
| Strom SBSP7c Single-phase Electric | 7000 |
| Strom SBSP18c 3-phase Electric Combi Boiler | 18,000 |
| Strom SBSP11c Single-phase Electric Combi Boiler | 10,000 |
| Slim Jim 10kw Electric Flow Boiler EHCS | 10,000 |
| Slim Jim 7kw Electric Flow Boiler EHCS | 7000 |
As you can see, the power ratings vary between different boilers. So you should take the time to check your own appliance.
How Much Electricity Does a Boiler Use?
You can use boiler wattage to work out how much electricity it uses. Plus this can be useful in understanding how much it costs to run your boiler.
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 boiler drawing 10,000W would use 10,000Wh when running for an hour.
Happily, electricity bills are recorded in kilowatt-hours (kWh). A kilowatt is simply 1000 watts. So a 10,000W boiler running for 1 hour uses 10kWh.
In reality, your boiler heats water for 3 hours a day. This means a 10kW boiler uses about 30,000Wh or 30kWh electricity a day. That’s 900kWh a month and 10,800kWh a year.
That’s a rough electricity cost of $4.5 a day or $1,620 a year to heat water from an electric boiler for 3 hours each day.
The exact number will vary from home to home. For example, you might not use your boiler for so many hours in the summer when the central heating is switched on.
How Many Watts Does a Boiler Use Summary
I hope you now understand how many watts a electric boiler uses.
There’s no doubt that electric boilers are efficient. Every watt of electricity goes into heating water to keep your home warm. You should still know that they will use a lot of power. After installing one of these boilers you’ll certainly notice an increase on your electricity bill. Of course, your gas or oil costs will disappear too so it balances out in the long overall.
