Can A Portable Generator Run A Boiler: What You Need To Know

Last Updated on September 26, 2023 by mfttherese

how many watts does a boiler use

The last thing you want to deal with in the winter is a blackout that could render your boiler useless.

Without a functioning boiler, you will be stuck without a heating source, and in the middle of winter, this could be devastating to your and your family.

Having a backup power source, such as a portable generator, can get your furnace powered back up quickly.

How many watts does a boiler use?

The power requirement for an average small boiler sits at around 200 watts during operation. However, at the onset, the burner motor requires a surge power of approximately three times that amount, which brings us to 600 watts at its peak. Also keep in mind the boiler’s circulator uses around 100 watts while functioning and demands a starting power of about 300 watts.

Before running out and buying the first generator that you see, it is important to figure out how many watts your boiler needs to run.This will allow you to find a generator that can power the boiler easily and if needed, power other accessories safely.

Now that you know just how many watts you need, you can start doing your research on the perfect generator.

Let’s look at larger boilers that require even more power. Most standard household boilers operate at 1500-2000 watts depending on the size of the boiler.

Some larger homes may have multiple boilers.
I know how this can be a little confusing, so I am going to break it down for you to help you better understand exactly how to figure out your wattage needs.

If your boiler operates at 1500 watts, you will need a generator that is rated at 1500 running watts or more.

I suggest getting one that has a little more running watts than what you need, just in case you need it.

In most cases, I have seen homeowners go with 500-1000 watts over what they need to help power smaller appliances while keeping their boiler running at all times.

Starting Watts VS Running Watts

While researching generators, you are going to notice that there are two different ratings, starting watts and running watts.Although the terms basically define them, I am going to go into a little bit of detail on each to give you a better understanding of how important it is to know what you are buying.

Running watts, also known as rated watts, are the most popular metric used to measure a generator’s output.

This is the maximum number of watts that the generator can produce to keep your appliance running.

For example, if you have a 2000 watt boiler, you are going to need at least a 2000 watt rated generator to keep it running.

Starting watts, a wattage that is always greater than the rated watts, is the number of watts that a generator can produce for the few seconds to start appliances.

Wattage demands go up when starting motor-driven products such as a refrigerator or large tools.

This is the largest amount of wattage a generator can produce, but it cannot constantly run at this wattage.

Can you run a boiler off a generator?

The short answer is yes! Many boilers are designed to run on electricity, and generators can supply this power. From our broad range of tests and practical experience, we know for a fact that you can run a boiler off a generator. We’ve seen all kinds of different size boilers tested. These units have been operating successfully on generator power over extensive periods.

It’s important, however, to ensure that the generator has enough capacity to handle the power demands of the boiler, especially during startup (as we discussed above) when the power consumption can spike significantly. It’s always wise to consult with a professional or refer to your boiler’s and generator’s manuals for specific requirements and safety precautions.

Average Boiler Wattage?

electric water boiler in a garageDue to the various size boilers on the market, it is hard to know exactly which generator is best for you without looking at your exact boiler specs.

As discussed earlier, most homes with a small sized single boiler system operate in the 1500-2000 watt area.

To find out exactly what you need, check your boiler for a manufacturer tag or look up your model number online to get the exact wattage demands.

Spend a little extra time researching if you need to as incorrect guesses could be a costly mistake.

What size generator to run a boiler

When choosing which size generator to run your boiler, you’ll have to consider several things. Here are just a few of them:

  • Understanding the power usage of the boiler is crucial in determining the size of the generator needed.
  • It is important to find the right balance between enough power and cost when selecting a generator.
  • Conducting a load calculation is necessary to avoid overloading or under-utilizing the generator.
  • Consider factors such as boiler efficiency, power consumption, and fuel options when choosing the right size generator for the boiler.

This is NOT a one-size-fits-all situation!

For example, if you’ve got a large industrial boiler, you might need a generator with a much higher output than someone who’s just trying to keep their small house warm.

It’s crucial to consider factors like Boiler Efficiency and Power Consumption – two key elements that can significantly impact the size of the generator needed. Below we share two portable generators that can easily run small boilers.

Two Portable Generators For Small Boilers

To adequately power your boiler through your next power outage, you are going to need a portable generator that can keep up with the demand.

Here are the two best generators for boiler:

1. Honda EU2200i Inverter (Starting watts 2200, Running 1800)

With the average boiler needing about 1500-2000 watts, this Honda EU2200i delivers just that plus more!

This is crucial when trying to power more than just your boiler.

Since you will most likely be having to grab this generator and go in a hurry, the integrated handle and lightweight construction are great features to consider on this Honda generator.

The easy-to-use control panel also makes for a quick and easy setup.

One of the biggest factors when looking for a portable generator is noise level.

Due to the boiler location, you will most likely be having to take into account the noise of the generator for both you and your neighbors.

At only 48-57 dBa, you can rest assure that this will be one of the quietest you can get.

2. Westinghouse iGen2200

In the same power range as the Honda EU2200i, Westinghouse provides a generator that is also great for powering a boiler with their iGen2200 inverter generator.

With 2200 starting watts and 1800 running watts, you should have more than enough power output for boilers in the 1500 watt range.

This leaves you with the capability of powering other appliances at the same time.

igen 2200 generator from westinghouse powered up

Needing to use this generator near other homes? No problem!

The 52 dBa noise level is a customer favorite feature as it is very neighborhood friendly.

With a large 1.2 gallon tank, the iGen2200 is capable of running for up to 12 hours at 25% load.

Of course, with a boiler, you will be using more than likely about 80% load where running time will decrease.

This generator does come equipped with an efficiency mode that can be turned on for maximum fuel efficiency.

Many Boilers Require More Watts
Depending on the type and size of your boiler, you might need more power. It is not uncommon for electric water heaters to un in the 5,000 or even 10,000 watts range. You can find a selection of generators around 5,000 watts here and 10,000 watts here


Keeping you and your family safe and warm is priority number one during a blackout or natural disaster.

Having the right equipment to do so ahead of time is key.
A boiler can easily be powered by a portable generator as long as you take the proper precautions on getting the correct size generator and getting is safely hooked up.

Always remember to check the wattage demands of your boiler and the wattage specifications of the generator you are wanting to use to avoid any potential injury.

Let me know in the comments if you have any questions about powering a boiler with a portable generator! is an independent review business. I am not affiliated with any manufacturers and do not accept paid reviews. When you buy through my links, I may earn a commission which helps me purchase more generators for testing. - Scott Krager

One comment

  1. I have a 2000w inverter generator I calculate my oil fired hot water furnace draws about 1400 watts, 12a times 115v can this generator run this furnace

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